Merge pull request #102735 from dims/switch-to-github.com/robfig/cron/v3

Update to github.com/robfig/cron/v3

LICENSES/vendor/github.com/robfig/cron/v3/LICENSE

@@ -1,4 +1,4 @@
-= vendor/github.com/robfig/cron licensed under: =
+= vendor/github.com/robfig/cron/v3 licensed under: =
 
 Copyright (C) 2012 Rob Figueiredo
 All Rights Reserved.
@@ -22,4 +22,4 @@ COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
 IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 
-= vendor/github.com/robfig/cron/LICENSE d924a63cb54a2a6c4bd28c50b2b0af59
+= vendor/github.com/robfig/cron/v3/LICENSE d924a63cb54a2a6c4bd28c50b2b0af59

go.mod

@@ -78,7 +78,7 @@ require (
 	github.com/prometheus/client_model v0.2.0
 	github.com/prometheus/common v0.26.0
 	github.com/quobyte/api v0.1.8
-	github.com/robfig/cron v1.1.0
+	github.com/robfig/cron/v3 v3.0.1
 	github.com/spf13/afero v1.2.2
 	github.com/spf13/cobra v1.1.1
 	github.com/spf13/pflag v1.0.5
@@ -373,7 +373,7 @@ replace (
 	github.com/prometheus/procfs => github.com/prometheus/procfs v0.2.0
 	github.com/quobyte/api => github.com/quobyte/api v0.1.8
 	github.com/remyoudompheng/bigfft => github.com/remyoudompheng/bigfft v0.0.0-20170806203942-52369c62f446
-	github.com/robfig/cron => github.com/robfig/cron v1.1.0
+	github.com/robfig/cron/v3 => github.com/robfig/cron/v3 v3.0.1
 	github.com/rogpeppe/fastuuid => github.com/rogpeppe/fastuuid v0.0.0-20150106093220-6724a57986af
 	github.com/rogpeppe/go-internal => github.com/rogpeppe/go-internal v1.3.0
 	github.com/rubiojr/go-vhd => github.com/rubiojr/go-vhd v0.0.0-20200706105327-02e210299021

go.sum

@@ -389,8 +389,8 @@ github.com/prometheus/procfs v0.2.0/go.mod h1:lV6e/gmhEcM9IjHGsFOCxxuZ+z1YqCvr4O
 github.com/quobyte/api v0.1.8 h1:+sOX1gIlC/OaLipqVZWrHgly9Kh9Qo8OygeS0mWAg30=
 github.com/quobyte/api v0.1.8/go.mod h1:jL7lIHrmqQ7yh05OJ+eEEdHr0u/kmT1Ff9iHd+4H6VI=
 github.com/remyoudompheng/bigfft v0.0.0-20170806203942-52369c62f446/go.mod h1:uYEyJGbgTkfkS4+E/PavXkNJcbFIpEtjt2B0KDQ5+9M=
-github.com/robfig/cron v1.1.0 h1:jk4/Hud3TTdcrJgUOBgsqrZBarcxl6ADIjSC2iniwLY=
-github.com/robfig/cron v1.1.0/go.mod h1:JGuDeoQd7Z6yL4zQhZ3OPEVHB7fL6Ka6skscFHfmt2k=
+github.com/robfig/cron/v3 v3.0.1 h1:WdRxkvbJztn8LMz/QEvLN5sBU+xKpSqwwUO1Pjr4qDs=
+github.com/robfig/cron/v3 v3.0.1/go.mod h1:eQICP3HwyT7UooqI/z+Ov+PtYAWygg1TEWWzGIFLtro=
 github.com/rogpeppe/fastuuid v0.0.0-20150106093220-6724a57986af/go.mod h1:XWv6SoW27p1b0cqNHllgS5HIMJraePCO15w5zCzIWYg=
 github.com/rogpeppe/go-internal v1.3.0/go.mod h1:M8bDsm7K2OlrFYOpmOWEs/qY81heoFRclV5y23lUDJ4=
 github.com/rubiojr/go-vhd v0.0.0-20200706105327-02e210299021 h1:if3/24+h9Sq6eDx8UUz1SO9cT9tizyIsATfB7b4D3tc=

pkg/apis/batch/validation/validation.go

@@ -19,7 +19,7 @@ package validation
 import (
 	"fmt"
 
-	"github.com/robfig/cron"
+	"github.com/robfig/cron/v3"
 
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	unversionedvalidation "k8s.io/apimachinery/pkg/apis/meta/v1/validation"

pkg/controller/cronjob/cronjob_controllerv2.go

@@ -22,7 +22,7 @@ import (
 	"sort"
 	"time"
 
-	"github.com/robfig/cron"
+	"github.com/robfig/cron/v3"
 
 	batchv1 "k8s.io/api/batch/v1"
 	corev1 "k8s.io/api/core/v1"

pkg/controller/cronjob/cronjob_controllerv2_test.go

@@ -22,7 +22,7 @@ import (
 	"testing"
 	"time"
 
-	"github.com/robfig/cron"
+	"github.com/robfig/cron/v3"
 
 	batchv1 "k8s.io/api/batch/v1"
 	"k8s.io/api/core/v1"

pkg/controller/cronjob/utils.go

@@ -20,7 +20,7 @@ import (
 	"fmt"
 	"time"
 
-	"github.com/robfig/cron"
+	"github.com/robfig/cron/v3"
 	"k8s.io/klog/v2"
 
 	batchv1 "k8s.io/api/batch/v1"

pkg/controller/cronjob/utils_test.go

@@ -23,7 +23,7 @@ import (
 	"testing"
 	"time"
 
-	cron "github.com/robfig/cron"
+	cron "github.com/robfig/cron/v3"
 	batchv1 "k8s.io/api/batch/v1"
 	"k8s.io/api/core/v1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"

vendor/github.com/robfig/cron/README.md

@@ -1,6 +0,0 @@
-[![GoDoc](http://godoc.org/github.com/robfig/cron?status.png)](http://godoc.org/github.com/robfig/cron) 
-[![Build Status](https://travis-ci.org/robfig/cron.svg?branch=master)](https://travis-ci.org/robfig/cron)
-
-# cron
-
-Documentation here: https://godoc.org/github.com/robfig/cron

vendor/github.com/robfig/cron/cron.go

@@ -1,259 +0,0 @@
-package cron
-
-import (
-	"log"
-	"runtime"
-	"sort"
-	"time"
-)
-
-// Cron keeps track of any number of entries, invoking the associated func as
-// specified by the schedule. It may be started, stopped, and the entries may
-// be inspected while running.
-type Cron struct {
-	entries  []*Entry
-	stop     chan struct{}
-	add      chan *Entry
-	snapshot chan []*Entry
-	running  bool
-	ErrorLog *log.Logger
-	location *time.Location
-}
-
-// Job is an interface for submitted cron jobs.
-type Job interface {
-	Run()
-}
-
-// The Schedule describes a job's duty cycle.
-type Schedule interface {
-	// Return the next activation time, later than the given time.
-	// Next is invoked initially, and then each time the job is run.
-	Next(time.Time) time.Time
-}
-
-// Entry consists of a schedule and the func to execute on that schedule.
-type Entry struct {
-	// The schedule on which this job should be run.
-	Schedule Schedule
-
-	// The next time the job will run. This is the zero time if Cron has not been
-	// started or this entry's schedule is unsatisfiable
-	Next time.Time
-
-	// The last time this job was run. This is the zero time if the job has never
-	// been run.
-	Prev time.Time
-
-	// The Job to run.
-	Job Job
-}
-
-// byTime is a wrapper for sorting the entry array by time
-// (with zero time at the end).
-type byTime []*Entry
-
-func (s byTime) Len() int      { return len(s) }
-func (s byTime) Swap(i, j int) { s[i], s[j] = s[j], s[i] }
-func (s byTime) Less(i, j int) bool {
-	// Two zero times should return false.
-	// Otherwise, zero is "greater" than any other time.
-	// (To sort it at the end of the list.)
-	if s[i].Next.IsZero() {
-		return false
-	}
-	if s[j].Next.IsZero() {
-		return true
-	}
-	return s[i].Next.Before(s[j].Next)
-}
-
-// New returns a new Cron job runner, in the Local time zone.
-func New() *Cron {
-	return NewWithLocation(time.Now().Location())
-}
-
-// NewWithLocation returns a new Cron job runner.
-func NewWithLocation(location *time.Location) *Cron {
-	return &Cron{
-		entries:  nil,
-		add:      make(chan *Entry),
-		stop:     make(chan struct{}),
-		snapshot: make(chan []*Entry),
-		running:  false,
-		ErrorLog: nil,
-		location: location,
-	}
-}
-
-// A wrapper that turns a func() into a cron.Job
-type FuncJob func()
-
-func (f FuncJob) Run() { f() }
-
-// AddFunc adds a func to the Cron to be run on the given schedule.
-func (c *Cron) AddFunc(spec string, cmd func()) error {
-	return c.AddJob(spec, FuncJob(cmd))
-}
-
-// AddJob adds a Job to the Cron to be run on the given schedule.
-func (c *Cron) AddJob(spec string, cmd Job) error {
-	schedule, err := Parse(spec)
-	if err != nil {
-		return err
-	}
-	c.Schedule(schedule, cmd)
-	return nil
-}
-
-// Schedule adds a Job to the Cron to be run on the given schedule.
-func (c *Cron) Schedule(schedule Schedule, cmd Job) {
-	entry := &Entry{
-		Schedule: schedule,
-		Job:      cmd,
-	}
-	if !c.running {
-		c.entries = append(c.entries, entry)
-		return
-	}
-
-	c.add <- entry
-}
-
-// Entries returns a snapshot of the cron entries.
-func (c *Cron) Entries() []*Entry {
-	if c.running {
-		c.snapshot <- nil
-		x := <-c.snapshot
-		return x
-	}
-	return c.entrySnapshot()
-}
-
-// Location gets the time zone location
-func (c *Cron) Location() *time.Location {
-	return c.location
-}
-
-// Start the cron scheduler in its own go-routine, or no-op if already started.
-func (c *Cron) Start() {
-	if c.running {
-		return
-	}
-	c.running = true
-	go c.run()
-}
-
-// Run the cron scheduler, or no-op if already running.
-func (c *Cron) Run() {
-	if c.running {
-		return
-	}
-	c.running = true
-	c.run()
-}
-
-func (c *Cron) runWithRecovery(j Job) {
-	defer func() {
-		if r := recover(); r != nil {
-			const size = 64 << 10
-			buf := make([]byte, size)
-			buf = buf[:runtime.Stack(buf, false)]
-			c.logf("cron: panic running job: %v\n%s", r, buf)
-		}
-	}()
-	j.Run()
-}
-
-// Run the scheduler. this is private just due to the need to synchronize
-// access to the 'running' state variable.
-func (c *Cron) run() {
-	// Figure out the next activation times for each entry.
-	now := c.now()
-	for _, entry := range c.entries {
-		entry.Next = entry.Schedule.Next(now)
-	}
-
-	for {
-		// Determine the next entry to run.
-		sort.Sort(byTime(c.entries))
-
-		var timer *time.Timer
-		if len(c.entries) == 0 || c.entries[0].Next.IsZero() {
-			// If there are no entries yet, just sleep - it still handles new entries
-			// and stop requests.
-			timer = time.NewTimer(100000 * time.Hour)
-		} else {
-			timer = time.NewTimer(c.entries[0].Next.Sub(now))
-		}
-
-		for {
-			select {
-			case now = <-timer.C:
-				now = now.In(c.location)
-				// Run every entry whose next time was less than now
-				for _, e := range c.entries {
-					if e.Next.After(now) || e.Next.IsZero() {
-						break
-					}
-					go c.runWithRecovery(e.Job)
-					e.Prev = e.Next
-					e.Next = e.Schedule.Next(now)
-				}
-
-			case newEntry := <-c.add:
-				timer.Stop()
-				now = c.now()
-				newEntry.Next = newEntry.Schedule.Next(now)
-				c.entries = append(c.entries, newEntry)
-
-			case <-c.snapshot:
-				c.snapshot <- c.entrySnapshot()
-				continue
-
-			case <-c.stop:
-				timer.Stop()
-				return
-			}
-
-			break
-		}
-	}
-}
-
-// Logs an error to stderr or to the configured error log
-func (c *Cron) logf(format string, args ...interface{}) {
-	if c.ErrorLog != nil {
-		c.ErrorLog.Printf(format, args...)
-	} else {
-		log.Printf(format, args...)
-	}
-}
-
-// Stop stops the cron scheduler if it is running; otherwise it does nothing.
-func (c *Cron) Stop() {
-	if !c.running {
-		return
-	}
-	c.stop <- struct{}{}
-	c.running = false
-}
-
-// entrySnapshot returns a copy of the current cron entry list.
-func (c *Cron) entrySnapshot() []*Entry {
-	entries := []*Entry{}
-	for _, e := range c.entries {
-		entries = append(entries, &Entry{
-			Schedule: e.Schedule,
-			Next:     e.Next,
-			Prev:     e.Prev,
-			Job:      e.Job,
-		})
-	}
-	return entries
-}
-
-// now returns current time in c location
-func (c *Cron) now() time.Time {
-	return time.Now().In(c.location)
-}

vendor/github.com/robfig/cron/v3/README.md

@@ -0,0 +1,125 @@
+[![GoDoc](http://godoc.org/github.com/robfig/cron?status.png)](http://godoc.org/github.com/robfig/cron)
+[![Build Status](https://travis-ci.org/robfig/cron.svg?branch=master)](https://travis-ci.org/robfig/cron)
+
+# cron
+
+Cron V3 has been released!
+
+To download the specific tagged release, run:
+
+	go get github.com/robfig/cron/v3@v3.0.0
+
+Import it in your program as:
+
+	import "github.com/robfig/cron/v3"
+
+It requires Go 1.11 or later due to usage of Go Modules.
+
+Refer to the documentation here:
+http://godoc.org/github.com/robfig/cron
+
+The rest of this document describes the the advances in v3 and a list of
+breaking changes for users that wish to upgrade from an earlier version.
+
+## Upgrading to v3 (June 2019)
+
+cron v3 is a major upgrade to the library that addresses all outstanding bugs,
+feature requests, and rough edges. It is based on a merge of master which
+contains various fixes to issues found over the years and the v2 branch which
+contains some backwards-incompatible features like the ability to remove cron
+jobs. In addition, v3 adds support for Go Modules, cleans up rough edges like
+the timezone support, and fixes a number of bugs.
+
+New features:
+
+- Support for Go modules. Callers must now import this library as
+  `github.com/robfig/cron/v3`, instead of `gopkg.in/...`
+
+- Fixed bugs:
+  - 0f01e6b parser: fix combining of Dow and Dom (#70)
+  - dbf3220 adjust times when rolling the clock forward to handle non-existent midnight (#157)
+  - eeecf15 spec_test.go: ensure an error is returned on 0 increment (#144)
+  - 70971dc cron.Entries(): update request for snapshot to include a reply channel (#97)
+  - 1cba5e6 cron: fix: removing a job causes the next scheduled job to run too late (#206)
+
+- Standard cron spec parsing by default (first field is "minute"), with an easy
+  way to opt into the seconds field (quartz-compatible). Although, note that the
+  year field (optional in Quartz) is not supported.
+
+- Extensible, key/value logging via an interface that complies with
+  the https://github.com/go-logr/logr project.
+
+- The new Chain & JobWrapper types allow you to install "interceptors" to add
+  cross-cutting behavior like the following:
+  - Recover any panics from jobs
+  - Delay a job's execution if the previous run hasn't completed yet
+  - Skip a job's execution if the previous run hasn't completed yet
+  - Log each job's invocations
+  - Notification when jobs are completed
+
+It is backwards incompatible with both v1 and v2. These updates are required:
+
+- The v1 branch accepted an optional seconds field at the beginning of the cron
+  spec. This is non-standard and has led to a lot of confusion. The new default
+  parser conforms to the standard as described by [the Cron wikipedia page].
+
+  UPDATING: To retain the old behavior, construct your Cron with a custom
+  parser:
+
+      // Seconds field, required
+      cron.New(cron.WithSeconds())
+
+      // Seconds field, optional
+      cron.New(
+          cron.WithParser(
+              cron.SecondOptional | cron.Minute | cron.Hour | cron.Dom | cron.Month | cron.Dow | cron.Descriptor))
+
+- The Cron type now accepts functional options on construction rather than the
+  previous ad-hoc behavior modification mechanisms (setting a field, calling a setter).
+
+  UPDATING: Code that sets Cron.ErrorLogger or calls Cron.SetLocation must be
+  updated to provide those values on construction.
+
+- CRON_TZ is now the recommended way to specify the timezone of a single
+  schedule, which is sanctioned by the specification. The legacy "TZ=" prefix
+  will continue to be supported since it is unambiguous and easy to do so.
+
+  UPDATING: No update is required.
+
+- By default, cron will no longer recover panics in jobs that it runs.
+  Recovering can be surprising (see issue #192) and seems to be at odds with
+  typical behavior of libraries. Relatedly, the `cron.WithPanicLogger` option
+  has been removed to accommodate the more general JobWrapper type.
+
+  UPDATING: To opt into panic recovery and configure the panic logger:
+
+      cron.New(cron.WithChain(
+          cron.Recover(logger),  // or use cron.DefaultLogger
+      ))
+
+- In adding support for https://github.com/go-logr/logr, `cron.WithVerboseLogger` was
+  removed, since it is duplicative with the leveled logging.
+
+  UPDATING: Callers should use `WithLogger` and specify a logger that does not
+  discard `Info` logs. For convenience, one is provided that wraps `*log.Logger`:
+
+      cron.New(
+          cron.WithLogger(cron.VerbosePrintfLogger(logger)))
+
+
+### Background - Cron spec format
+
+There are two cron spec formats in common usage:
+
+- The "standard" cron format, described on [the Cron wikipedia page] and used by
+  the cron Linux system utility.
+
+- The cron format used by [the Quartz Scheduler], commonly used for scheduled
+  jobs in Java software
+
+[the Cron wikipedia page]: https://en.wikipedia.org/wiki/Cron
+[the Quartz Scheduler]: http://www.quartz-scheduler.org/documentation/quartz-2.3.0/tutorials/tutorial-lesson-06.html
+
+The original version of this package included an optional "seconds" field, which
+made it incompatible with both of these formats. Now, the "standard" format is
+the default format accepted, and the Quartz format is opt-in.

vendor/github.com/robfig/cron/v3/chain.go

@@ -0,0 +1,92 @@
+package cron
+
+import (
+	"fmt"
+	"runtime"
+	"sync"
+	"time"
+)
+
+// JobWrapper decorates the given Job with some behavior.
+type JobWrapper func(Job) Job
+
+// Chain is a sequence of JobWrappers that decorates submitted jobs with
+// cross-cutting behaviors like logging or synchronization.
+type Chain struct {
+	wrappers []JobWrapper
+}
+
+// NewChain returns a Chain consisting of the given JobWrappers.
+func NewChain(c ...JobWrapper) Chain {
+	return Chain{c}
+}
+
+// Then decorates the given job with all JobWrappers in the chain.
+//
+// This:
+//     NewChain(m1, m2, m3).Then(job)
+// is equivalent to:
+//     m1(m2(m3(job)))
+func (c Chain) Then(j Job) Job {
+	for i := range c.wrappers {
+		j = c.wrappers[len(c.wrappers)-i-1](j)
+	}
+	return j
+}
+
+// Recover panics in wrapped jobs and log them with the provided logger.
+func Recover(logger Logger) JobWrapper {
+	return func(j Job) Job {
+		return FuncJob(func() {
+			defer func() {
+				if r := recover(); r != nil {
+					const size = 64 << 10
+					buf := make([]byte, size)
+					buf = buf[:runtime.Stack(buf, false)]
+					err, ok := r.(error)
+					if !ok {
+						err = fmt.Errorf("%v", r)
+					}
+					logger.Error(err, "panic", "stack", "...\n"+string(buf))
+				}
+			}()
+			j.Run()
+		})
+	}
+}
+
+// DelayIfStillRunning serializes jobs, delaying subsequent runs until the
+// previous one is complete. Jobs running after a delay of more than a minute
+// have the delay logged at Info.
+func DelayIfStillRunning(logger Logger) JobWrapper {
+	return func(j Job) Job {
+		var mu sync.Mutex
+		return FuncJob(func() {
+			start := time.Now()
+			mu.Lock()
+			defer mu.Unlock()
+			if dur := time.Since(start); dur > time.Minute {
+				logger.Info("delay", "duration", dur)
+			}
+			j.Run()
+		})
+	}
+}
+
+// SkipIfStillRunning skips an invocation of the Job if a previous invocation is
+// still running. It logs skips to the given logger at Info level.
+func SkipIfStillRunning(logger Logger) JobWrapper {
+	return func(j Job) Job {
+		var ch = make(chan struct{}, 1)
+		ch <- struct{}{}
+		return FuncJob(func() {
+			select {
+			case v := <-ch:
+				j.Run()
+				ch <- v
+			default:
+				logger.Info("skip")
+			}
+		})
+	}
+}

vendor/github.com/robfig/cron/v3/cron.go

@@ -0,0 +1,355 @@
+package cron
+
+import (
+	"context"
+	"sort"
+	"sync"
+	"time"
+)
+
+// Cron keeps track of any number of entries, invoking the associated func as
+// specified by the schedule. It may be started, stopped, and the entries may
+// be inspected while running.
+type Cron struct {
+	entries   []*Entry
+	chain     Chain
+	stop      chan struct{}
+	add       chan *Entry
+	remove    chan EntryID
+	snapshot  chan chan []Entry
+	running   bool
+	logger    Logger
+	runningMu sync.Mutex
+	location  *time.Location
+	parser    ScheduleParser
+	nextID    EntryID
+	jobWaiter sync.WaitGroup
+}
+
+// ScheduleParser is an interface for schedule spec parsers that return a Schedule
+type ScheduleParser interface {
+	Parse(spec string) (Schedule, error)
+}
+
+// Job is an interface for submitted cron jobs.
+type Job interface {
+	Run()
+}
+
+// Schedule describes a job's duty cycle.
+type Schedule interface {
+	// Next returns the next activation time, later than the given time.
+	// Next is invoked initially, and then each time the job is run.
+	Next(time.Time) time.Time
+}
+
+// EntryID identifies an entry within a Cron instance
+type EntryID int
+
+// Entry consists of a schedule and the func to execute on that schedule.
+type Entry struct {
+	// ID is the cron-assigned ID of this entry, which may be used to look up a
+	// snapshot or remove it.
+	ID EntryID
+
+	// Schedule on which this job should be run.
+	Schedule Schedule
+
+	// Next time the job will run, or the zero time if Cron has not been
+	// started or this entry's schedule is unsatisfiable
+	Next time.Time
+
+	// Prev is the last time this job was run, or the zero time if never.
+	Prev time.Time
+
+	// WrappedJob is the thing to run when the Schedule is activated.
+	WrappedJob Job
+
+	// Job is the thing that was submitted to cron.
+	// It is kept around so that user code that needs to get at the job later,
+	// e.g. via Entries() can do so.
+	Job Job
+}
+
+// Valid returns true if this is not the zero entry.
+func (e Entry) Valid() bool { return e.ID != 0 }
+
+// byTime is a wrapper for sorting the entry array by time
+// (with zero time at the end).
+type byTime []*Entry
+
+func (s byTime) Len() int      { return len(s) }
+func (s byTime) Swap(i, j int) { s[i], s[j] = s[j], s[i] }
+func (s byTime) Less(i, j int) bool {
+	// Two zero times should return false.
+	// Otherwise, zero is "greater" than any other time.
+	// (To sort it at the end of the list.)
+	if s[i].Next.IsZero() {
+		return false
+	}
+	if s[j].Next.IsZero() {
+		return true
+	}
+	return s[i].Next.Before(s[j].Next)
+}
+
+// New returns a new Cron job runner, modified by the given options.
+//
+// Available Settings
+//
+//   Time Zone
+//     Description: The time zone in which schedules are interpreted
+//     Default:     time.Local
+//
+//   Parser
+//     Description: Parser converts cron spec strings into cron.Schedules.
+//     Default:     Accepts this spec: https://en.wikipedia.org/wiki/Cron
+//
+//   Chain
+//     Description: Wrap submitted jobs to customize behavior.
+//     Default:     A chain that recovers panics and logs them to stderr.
+//
+// See "cron.With*" to modify the default behavior.
+func New(opts ...Option) *Cron {
+	c := &Cron{
+		entries:   nil,
+		chain:     NewChain(),
+		add:       make(chan *Entry),
+		stop:      make(chan struct{}),
+		snapshot:  make(chan chan []Entry),
+		remove:    make(chan EntryID),
+		running:   false,
+		runningMu: sync.Mutex{},
+		logger:    DefaultLogger,
+		location:  time.Local,
+		parser:    standardParser,
+	}
+	for _, opt := range opts {
+		opt(c)
+	}
+	return c
+}
+
+// FuncJob is a wrapper that turns a func() into a cron.Job
+type FuncJob func()
+
+func (f FuncJob) Run() { f() }
+
+// AddFunc adds a func to the Cron to be run on the given schedule.
+// The spec is parsed using the time zone of this Cron instance as the default.
+// An opaque ID is returned that can be used to later remove it.
+func (c *Cron) AddFunc(spec string, cmd func()) (EntryID, error) {
+	return c.AddJob(spec, FuncJob(cmd))
+}
+
+// AddJob adds a Job to the Cron to be run on the given schedule.
+// The spec is parsed using the time zone of this Cron instance as the default.
+// An opaque ID is returned that can be used to later remove it.
+func (c *Cron) AddJob(spec string, cmd Job) (EntryID, error) {
+	schedule, err := c.parser.Parse(spec)
+	if err != nil {
+		return 0, err
+	}
+	return c.Schedule(schedule, cmd), nil
+}
+
+// Schedule adds a Job to the Cron to be run on the given schedule.
+// The job is wrapped with the configured Chain.
+func (c *Cron) Schedule(schedule Schedule, cmd Job) EntryID {
+	c.runningMu.Lock()
+	defer c.runningMu.Unlock()
+	c.nextID++
+	entry := &Entry{
+		ID:         c.nextID,
+		Schedule:   schedule,
+		WrappedJob: c.chain.Then(cmd),
+		Job:        cmd,
+	}
+	if !c.running {
+		c.entries = append(c.entries, entry)
+	} else {
+		c.add <- entry
+	}
+	return entry.ID
+}
+
+// Entries returns a snapshot of the cron entries.
+func (c *Cron) Entries() []Entry {
+	c.runningMu.Lock()
+	defer c.runningMu.Unlock()
+	if c.running {
+		replyChan := make(chan []Entry, 1)
+		c.snapshot <- replyChan
+		return <-replyChan
+	}
+	return c.entrySnapshot()
+}
+
+// Location gets the time zone location
+func (c *Cron) Location() *time.Location {
+	return c.location
+}
+
+// Entry returns a snapshot of the given entry, or nil if it couldn't be found.
+func (c *Cron) Entry(id EntryID) Entry {
+	for _, entry := range c.Entries() {
+		if id == entry.ID {
+			return entry
+		}
+	}
+	return Entry{}
+}
+
+// Remove an entry from being run in the future.
+func (c *Cron) Remove(id EntryID) {
+	c.runningMu.Lock()
+	defer c.runningMu.Unlock()
+	if c.running {
+		c.remove <- id
+	} else {
+		c.removeEntry(id)
+	}
+}
+
+// Start the cron scheduler in its own goroutine, or no-op if already started.
+func (c *Cron) Start() {
+	c.runningMu.Lock()
+	defer c.runningMu.Unlock()
+	if c.running {
+		return
+	}
+	c.running = true
+	go c.run()
+}
+
+// Run the cron scheduler, or no-op if already running.
+func (c *Cron) Run() {
+	c.runningMu.Lock()
+	if c.running {
+		c.runningMu.Unlock()
+		return
+	}
+	c.running = true
+	c.runningMu.Unlock()
+	c.run()
+}
+
+// run the scheduler.. this is private just due to the need to synchronize
+// access to the 'running' state variable.
+func (c *Cron) run() {
+	c.logger.Info("start")
+
+	// Figure out the next activation times for each entry.
+	now := c.now()
+	for _, entry := range c.entries {
+		entry.Next = entry.Schedule.Next(now)
+		c.logger.Info("schedule", "now", now, "entry", entry.ID, "next", entry.Next)
+	}
+
+	for {
+		// Determine the next entry to run.
+		sort.Sort(byTime(c.entries))
+
+		var timer *time.Timer
+		if len(c.entries) == 0 || c.entries[0].Next.IsZero() {
+			// If there are no entries yet, just sleep - it still handles new entries
+			// and stop requests.
+			timer = time.NewTimer(100000 * time.Hour)
+		} else {
+			timer = time.NewTimer(c.entries[0].Next.Sub(now))
+		}
+
+		for {
+			select {
+			case now = <-timer.C:
+				now = now.In(c.location)
+				c.logger.Info("wake", "now", now)
+
+				// Run every entry whose next time was less than now
+				for _, e := range c.entries {
+					if e.Next.After(now) || e.Next.IsZero() {
+						break
+					}
+					c.startJob(e.WrappedJob)
+					e.Prev = e.Next
+					e.Next = e.Schedule.Next(now)
+					c.logger.Info("run", "now", now, "entry", e.ID, "next", e.Next)
+				}
+
+			case newEntry := <-c.add:
+				timer.Stop()
+				now = c.now()
+				newEntry.Next = newEntry.Schedule.Next(now)
+				c.entries = append(c.entries, newEntry)
+				c.logger.Info("added", "now", now, "entry", newEntry.ID, "next", newEntry.Next)
+
+			case replyChan := <-c.snapshot:
+				replyChan <- c.entrySnapshot()
+				continue
+
+			case <-c.stop:
+				timer.Stop()
+				c.logger.Info("stop")
+				return
+
+			case id := <-c.remove:
+				timer.Stop()
+				now = c.now()
+				c.removeEntry(id)
+				c.logger.Info("removed", "entry", id)
+			}
+
+			break
+		}
+	}
+}
+
+// startJob runs the given job in a new goroutine.
+func (c *Cron) startJob(j Job) {
+	c.jobWaiter.Add(1)
+	go func() {
+		defer c.jobWaiter.Done()
+		j.Run()
+	}()
+}
+
+// now returns current time in c location
+func (c *Cron) now() time.Time {
+	return time.Now().In(c.location)
+}
+
+// Stop stops the cron scheduler if it is running; otherwise it does nothing.
+// A context is returned so the caller can wait for running jobs to complete.
+func (c *Cron) Stop() context.Context {
+	c.runningMu.Lock()
+	defer c.runningMu.Unlock()
+	if c.running {
+		c.stop <- struct{}{}
+		c.running = false
+	}
+	ctx, cancel := context.WithCancel(context.Background())
+	go func() {
+		c.jobWaiter.Wait()
+		cancel()
+	}()
+	return ctx
+}
+
+// entrySnapshot returns a copy of the current cron entry list.
+func (c *Cron) entrySnapshot() []Entry {
+	var entries = make([]Entry, len(c.entries))
+	for i, e := range c.entries {
+		entries[i] = *e
+	}
+	return entries
+}
+
+func (c *Cron) removeEntry(id EntryID) {
+	var entries []*Entry
+	for _, e := range c.entries {
+		if e.ID != id {
+			entries = append(entries, e)
+		}
+	}
+	c.entries = entries
+}

vendor/github.com/robfig/cron/v3/doc.go

@@ -1,15 +1,29 @@
 /*
 Package cron implements a cron spec parser and job runner.
 
+Installation
+
+To download the specific tagged release, run:
+
+	go get github.com/robfig/cron/v3@v3.0.0
+
+Import it in your program as:
+
+	import "github.com/robfig/cron/v3"
+
+It requires Go 1.11 or later due to usage of Go Modules.
+
 Usage
 
 Callers may register Funcs to be invoked on a given schedule.  Cron will run
 them in their own goroutines.
 
 	c := cron.New()
-	c.AddFunc("0 30 * * * *", func() { fmt.Println("Every hour on the half hour") })
-	c.AddFunc("@hourly",      func() { fmt.Println("Every hour") })
-	c.AddFunc("@every 1h30m", func() { fmt.Println("Every hour thirty") })
+	c.AddFunc("30 * * * *", func() { fmt.Println("Every hour on the half hour") })
+	c.AddFunc("30 3-6,20-23 * * *", func() { fmt.Println(".. in the range 3-6am, 8-11pm") })
+	c.AddFunc("CRON_TZ=Asia/Tokyo 30 04 * * *", func() { fmt.Println("Runs at 04:30 Tokyo time every day") })
+	c.AddFunc("@hourly",      func() { fmt.Println("Every hour, starting an hour from now") })
+	c.AddFunc("@every 1h30m", func() { fmt.Println("Every hour thirty, starting an hour thirty from now") })
 	c.Start()
 	..
 	// Funcs are invoked in their own goroutine, asynchronously.
@@ -24,19 +38,40 @@ them in their own goroutines.
 
 CRON Expression Format
 
-A cron expression represents a set of times, using 6 space-separated fields.
+A cron expression represents a set of times, using 5 space-separated fields.
 
 	Field name   | Mandatory? | Allowed values  | Allowed special characters
 	----------   | ---------- | --------------  | --------------------------
-	Seconds      | Yes        | 0-59            | * / , -
 	Minutes      | Yes        | 0-59            | * / , -
 	Hours        | Yes        | 0-23            | * / , -
 	Day of month | Yes        | 1-31            | * / , - ?
 	Month        | Yes        | 1-12 or JAN-DEC | * / , -
 	Day of week  | Yes        | 0-6 or SUN-SAT  | * / , - ?
 
-Note: Month and Day-of-week field values are case insensitive.  "SUN", "Sun",
-and "sun" are equally accepted.
+Month and Day-of-week field values are case insensitive.  "SUN", "Sun", and
+"sun" are equally accepted.
+
+The specific interpretation of the format is based on the Cron Wikipedia page:
+https://en.wikipedia.org/wiki/Cron
+
+Alternative Formats
+
+Alternative Cron expression formats support other fields like seconds. You can
+implement that by creating a custom Parser as follows.
+
+	cron.New(
+		cron.WithParser(
+			cron.NewParser(
+				cron.SecondOptional | cron.Minute | cron.Hour | cron.Dom | cron.Month | cron.Dow | cron.Descriptor)))
+
+Since adding Seconds is the most common modification to the standard cron spec,
+cron provides a builtin function to do that, which is equivalent to the custom
+parser you saw earlier, except that its seconds field is REQUIRED:
+
+	cron.New(cron.WithSeconds())
+
+That emulates Quartz, the most popular alternative Cron schedule format:
+http://www.quartz-scheduler.org/documentation/quartz-2.x/tutorials/crontrigger.html
 
 Special Characters
 
@@ -76,15 +111,15 @@ You may use one of several pre-defined schedules in place of a cron expression.
 
 	Entry                  | Description                                | Equivalent To
 	-----                  | -----------                                | -------------
-	@yearly (or @annually) | Run once a year, midnight, Jan. 1st        | 0 0 0 1 1 *
-	@monthly               | Run once a month, midnight, first of month | 0 0 0 1 * *
-	@weekly                | Run once a week, midnight between Sat/Sun  | 0 0 0 * * 0
-	@daily (or @midnight)  | Run once a day, midnight                   | 0 0 0 * * *
-	@hourly                | Run once an hour, beginning of hour        | 0 0 * * * *
+	@yearly (or @annually) | Run once a year, midnight, Jan. 1st        | 0 0 1 1 *
+	@monthly               | Run once a month, midnight, first of month | 0 0 1 * *
+	@weekly                | Run once a week, midnight between Sat/Sun  | 0 0 * * 0
+	@daily (or @midnight)  | Run once a day, midnight                   | 0 0 * * *
+	@hourly                | Run once an hour, beginning of hour        | 0 * * * *
 
 Intervals
 
-You may also schedule a job to execute at fixed intervals, starting at the time it's added 
+You may also schedule a job to execute at fixed intervals, starting at the time it's added
 or cron is run. This is supported by formatting the cron spec like this:
 
     @every <duration>
@@ -101,12 +136,62 @@ it will have only 2 minutes of idle time between each run.
 
 Time zones
 
-All interpretation and scheduling is done in the machine's local time zone (as
-provided by the Go time package (http://www.golang.org/pkg/time).
+By default, all interpretation and scheduling is done in the machine's local
+time zone (time.Local). You can specify a different time zone on construction:
+
+      cron.New(
+          cron.WithLocation(time.UTC))
+
+Individual cron schedules may also override the time zone they are to be
+interpreted in by providing an additional space-separated field at the beginning
+of the cron spec, of the form "CRON_TZ=Asia/Tokyo".
+
+For example:
+
+	# Runs at 6am in time.Local
+	cron.New().AddFunc("0 6 * * ?", ...)
+
+	# Runs at 6am in America/New_York
+	nyc, _ := time.LoadLocation("America/New_York")
+	c := cron.New(cron.WithLocation(nyc))
+	c.AddFunc("0 6 * * ?", ...)
+
+	# Runs at 6am in Asia/Tokyo
+	cron.New().AddFunc("CRON_TZ=Asia/Tokyo 0 6 * * ?", ...)
+
+	# Runs at 6am in Asia/Tokyo
+	c := cron.New(cron.WithLocation(nyc))
+	c.SetLocation("America/New_York")
+	c.AddFunc("CRON_TZ=Asia/Tokyo 0 6 * * ?", ...)
+
+The prefix "TZ=(TIME ZONE)" is also supported for legacy compatibility.
 
 Be aware that jobs scheduled during daylight-savings leap-ahead transitions will
 not be run!
 
+Job Wrappers
+
+A Cron runner may be configured with a chain of job wrappers to add
+cross-cutting functionality to all submitted jobs. For example, they may be used
+to achieve the following effects:
+
+  - Recover any panics from jobs (activated by default)
+  - Delay a job's execution if the previous run hasn't completed yet
+  - Skip a job's execution if the previous run hasn't completed yet
+  - Log each job's invocations
+
+Install wrappers for all jobs added to a cron using the `cron.WithChain` option:
+
+	cron.New(cron.WithChain(
+		cron.SkipIfStillRunning(logger),
+	))
+
+Install wrappers for individual jobs by explicitly wrapping them:
+
+	job = cron.NewChain(
+		cron.SkipIfStillRunning(logger),
+	).Then(job)
+
 Thread safety
 
 Since the Cron service runs concurrently with the calling code, some amount of
@@ -115,6 +200,23 @@ care must be taken to ensure proper synchronization.
 All cron methods are designed to be correctly synchronized as long as the caller
 ensures that invocations have a clear happens-before ordering between them.
 
+Logging
+
+Cron defines a Logger interface that is a subset of the one defined in
+github.com/go-logr/logr. It has two logging levels (Info and Error), and
+parameters are key/value pairs. This makes it possible for cron logging to plug
+into structured logging systems. An adapter, [Verbose]PrintfLogger, is provided
+to wrap the standard library *log.Logger.
+
+For additional insight into Cron operations, verbose logging may be activated
+which will record job runs, scheduling decisions, and added or removed jobs.
+Activate it with a one-off logger as follows:
+
+	cron.New(
+		cron.WithLogger(
+			cron.VerbosePrintfLogger(log.New(os.Stdout, "cron: ", log.LstdFlags))))
+
+
 Implementation
 
 Cron entries are stored in an array, sorted by their next activation time.  Cron

vendor/github.com/robfig/cron/v3/go.mod

@@ -0,0 +1,3 @@
+module github.com/robfig/cron/v3
+
+go 1.12

vendor/github.com/robfig/cron/v3/logger.go

@@ -0,0 +1,86 @@
+package cron
+
+import (
+	"io/ioutil"
+	"log"
+	"os"
+	"strings"
+	"time"
+)
+
+// DefaultLogger is used by Cron if none is specified.
+var DefaultLogger Logger = PrintfLogger(log.New(os.Stdout, "cron: ", log.LstdFlags))
+
+// DiscardLogger can be used by callers to discard all log messages.
+var DiscardLogger Logger = PrintfLogger(log.New(ioutil.Discard, "", 0))
+
+// Logger is the interface used in this package for logging, so that any backend
+// can be plugged in. It is a subset of the github.com/go-logr/logr interface.
+type Logger interface {
+	// Info logs routine messages about cron's operation.
+	Info(msg string, keysAndValues ...interface{})
+	// Error logs an error condition.
+	Error(err error, msg string, keysAndValues ...interface{})
+}
+
+// PrintfLogger wraps a Printf-based logger (such as the standard library "log")
+// into an implementation of the Logger interface which logs errors only.
+func PrintfLogger(l interface{ Printf(string, ...interface{}) }) Logger {
+	return printfLogger{l, false}
+}
+
+// VerbosePrintfLogger wraps a Printf-based logger (such as the standard library
+// "log") into an implementation of the Logger interface which logs everything.
+func VerbosePrintfLogger(l interface{ Printf(string, ...interface{}) }) Logger {
+	return printfLogger{l, true}
+}
+
+type printfLogger struct {
+	logger  interface{ Printf(string, ...interface{}) }
+	logInfo bool
+}
+
+func (pl printfLogger) Info(msg string, keysAndValues ...interface{}) {
+	if pl.logInfo {
+		keysAndValues = formatTimes(keysAndValues)
+		pl.logger.Printf(
+			formatString(len(keysAndValues)),
+			append([]interface{}{msg}, keysAndValues...)...)
+	}
+}
+
+func (pl printfLogger) Error(err error, msg string, keysAndValues ...interface{}) {
+	keysAndValues = formatTimes(keysAndValues)
+	pl.logger.Printf(
+		formatString(len(keysAndValues)+2),
+		append([]interface{}{msg, "error", err}, keysAndValues...)...)
+}
+
+// formatString returns a logfmt-like format string for the number of
+// key/values.
+func formatString(numKeysAndValues int) string {
+	var sb strings.Builder
+	sb.WriteString("%s")
+	if numKeysAndValues > 0 {
+		sb.WriteString(", ")
+	}
+	for i := 0; i < numKeysAndValues/2; i++ {
+		if i > 0 {
+			sb.WriteString(", ")
+		}
+		sb.WriteString("%v=%v")
+	}
+	return sb.String()
+}
+
+// formatTimes formats any time.Time values as RFC3339.
+func formatTimes(keysAndValues []interface{}) []interface{} {
+	var formattedArgs []interface{}
+	for _, arg := range keysAndValues {
+		if t, ok := arg.(time.Time); ok {
+			arg = t.Format(time.RFC3339)
+		}
+		formattedArgs = append(formattedArgs, arg)
+	}
+	return formattedArgs
+}

vendor/github.com/robfig/cron/v3/option.go

@@ -0,0 +1,45 @@
+package cron
+
+import (
+	"time"
+)
+
+// Option represents a modification to the default behavior of a Cron.
+type Option func(*Cron)
+
+// WithLocation overrides the timezone of the cron instance.
+func WithLocation(loc *time.Location) Option {
+	return func(c *Cron) {
+		c.location = loc
+	}
+}
+
+// WithSeconds overrides the parser used for interpreting job schedules to
+// include a seconds field as the first one.
+func WithSeconds() Option {
+	return WithParser(NewParser(
+		Second | Minute | Hour | Dom | Month | Dow | Descriptor,
+	))
+}
+
+// WithParser overrides the parser used for interpreting job schedules.
+func WithParser(p ScheduleParser) Option {
+	return func(c *Cron) {
+		c.parser = p
+	}
+}
+
+// WithChain specifies Job wrappers to apply to all jobs added to this cron.
+// Refer to the Chain* functions in this package for provided wrappers.
+func WithChain(wrappers ...JobWrapper) Option {
+	return func(c *Cron) {
+		c.chain = NewChain(wrappers...)
+	}
+}
+
+// WithLogger uses the provided logger.
+func WithLogger(logger Logger) Option {
+	return func(c *Cron) {
+		c.logger = logger
+	}
+}

vendor/github.com/robfig/cron/v3/parser.go

@@ -15,14 +15,15 @@ import (
 type ParseOption int
 
 const (
-	Second      ParseOption = 1 << iota // Seconds field, default 0
-	Minute                              // Minutes field, default 0
-	Hour                                // Hours field, default 0
-	Dom                                 // Day of month field, default *
-	Month                               // Month field, default *
-	Dow                                 // Day of week field, default *
-	DowOptional                         // Optional day of week field, default *
-	Descriptor                          // Allow descriptors such as @monthly, @weekly, etc.
+	Second         ParseOption = 1 << iota // Seconds field, default 0
+	SecondOptional                         // Optional seconds field, default 0
+	Minute                                 // Minutes field, default 0
+	Hour                                   // Hours field, default 0
+	Dom                                    // Day of month field, default *
+	Month                                  // Month field, default *
+	Dow                                    // Day of week field, default *
+	DowOptional                            // Optional day of week field, default *
+	Descriptor                             // Allow descriptors such as @monthly, @weekly, etc.
 )
 
 var places = []ParseOption{
@@ -45,11 +46,15 @@ var defaults = []string{
 
 // A custom Parser that can be configured.
 type Parser struct {
-	options   ParseOption
-	optionals int
+	options ParseOption
 }
 
-// Creates a custom Parser with custom options.
+// NewParser creates a Parser with custom options.
+//
+// It panics if more than one Optional is given, since it would be impossible to
+// correctly infer which optional is provided or missing in general.
+//
+// Examples
 //
 //  // Standard parser without descriptors
 //  specParser := NewParser(Minute | Hour | Dom | Month | Dow)
@@ -66,10 +71,15 @@ type Parser struct {
 func NewParser(options ParseOption) Parser {
 	optionals := 0
 	if options&DowOptional > 0 {
-		options |= Dow
 		optionals++
 	}
-	return Parser{options, optionals}
+	if options&SecondOptional > 0 {
+		optionals++
+	}
+	if optionals > 1 {
+		panic("multiple optionals may not be configured")
+	}
+	return Parser{options}
 }
 
 // Parse returns a new crontab schedule representing the given spec.
@@ -77,36 +87,39 @@ func NewParser(options ParseOption) Parser {
 // It accepts crontab specs and features configured by NewParser.
 func (p Parser) Parse(spec string) (Schedule, error) {
 	if len(spec) == 0 {
-		return nil, fmt.Errorf("Empty spec string")
-	}
-	if spec[0] == '@' && p.options&Descriptor > 0 {
-		return parseDescriptor(spec)
+		return nil, fmt.Errorf("empty spec string")
 	}
 
-	// Figure out how many fields we need
-	max := 0
-	for _, place := range places {
-		if p.options&place > 0 {
-			max++
+	// Extract timezone if present
+	var loc = time.Local
+	if strings.HasPrefix(spec, "TZ=") || strings.HasPrefix(spec, "CRON_TZ=") {
+		var err error
+		i := strings.Index(spec, " ")
+		eq := strings.Index(spec, "=")
+		if loc, err = time.LoadLocation(spec[eq+1 : i]); err != nil {
+			return nil, fmt.Errorf("provided bad location %s: %v", spec[eq+1:i], err)
 		}
+		spec = strings.TrimSpace(spec[i:])
 	}
-	min := max - p.optionals
 
-	// Split fields on whitespace
+	// Handle named schedules (descriptors), if configured
+	if strings.HasPrefix(spec, "@") {
+		if p.options&Descriptor == 0 {
+			return nil, fmt.Errorf("parser does not accept descriptors: %v", spec)
+		}
+		return parseDescriptor(spec, loc)
+	}
+
+	// Split on whitespace.
 	fields := strings.Fields(spec)
 
-	// Validate number of fields
-	if count := len(fields); count < min || count > max {
-		if min == max {
-			return nil, fmt.Errorf("Expected exactly %d fields, found %d: %s", min, count, spec)
-		}
-		return nil, fmt.Errorf("Expected %d to %d fields, found %d: %s", min, max, count, spec)
+	// Validate & fill in any omitted or optional fields
+	var err error
+	fields, err = normalizeFields(fields, p.options)
+	if err != nil {
+		return nil, err
 	}
 
-	// Fill in missing fields
-	fields = expandFields(fields, p.options)
-
-	var err error
 	field := func(field string, r bounds) uint64 {
 		if err != nil {
 			return 0
@@ -129,40 +142,86 @@ func (p Parser) Parse(spec string) (Schedule, error) {
 	}
 
 	return &SpecSchedule{
-		Second: second,
-		Minute: minute,
-		Hour:   hour,
-		Dom:    dayofmonth,
-		Month:  month,
-		Dow:    dayofweek,
+		Second:   second,
+		Minute:   minute,
+		Hour:     hour,
+		Dom:      dayofmonth,
+		Month:    month,
+		Dow:      dayofweek,
+		Location: loc,
 	}, nil
 }
 
-func expandFields(fields []string, options ParseOption) []string {
-	n := 0
-	count := len(fields)
-	expFields := make([]string, len(places))
-	copy(expFields, defaults)
-	for i, place := range places {
+// normalizeFields takes a subset set of the time fields and returns the full set
+// with defaults (zeroes) populated for unset fields.
+//
+// As part of performing this function, it also validates that the provided
+// fields are compatible with the configured options.
+func normalizeFields(fields []string, options ParseOption) ([]string, error) {
+	// Validate optionals & add their field to options
+	optionals := 0
+	if options&SecondOptional > 0 {
+		options |= Second
+		optionals++
+	}
+	if options&DowOptional > 0 {
+		options |= Dow
+		optionals++
+	}
+	if optionals > 1 {
+		return nil, fmt.Errorf("multiple optionals may not be configured")
+	}
+
+	// Figure out how many fields we need
+	max := 0
+	for _, place := range places {
 		if options&place > 0 {
-			expFields[i] = fields[n]
-			n++
-		}
-		if n == count {
-			break
+			max++
 		}
 	}
-	return expFields
+	min := max - optionals
+
+	// Validate number of fields
+	if count := len(fields); count < min || count > max {
+		if min == max {
+			return nil, fmt.Errorf("expected exactly %d fields, found %d: %s", min, count, fields)
+		}
+		return nil, fmt.Errorf("expected %d to %d fields, found %d: %s", min, max, count, fields)
+	}
+
+	// Populate the optional field if not provided
+	if min < max && len(fields) == min {
+		switch {
+		case options&DowOptional > 0:
+			fields = append(fields, defaults[5]) // TODO: improve access to default
+		case options&SecondOptional > 0:
+			fields = append([]string{defaults[0]}, fields...)
+		default:
+			return nil, fmt.Errorf("unknown optional field")
+		}
+	}
+
+	// Populate all fields not part of options with their defaults
+	n := 0
+	expandedFields := make([]string, len(places))
+	copy(expandedFields, defaults)
+	for i, place := range places {
+		if options&place > 0 {
+			expandedFields[i] = fields[n]
+			n++
+		}
+	}
+	return expandedFields, nil
 }
 
 var standardParser = NewParser(
 	Minute | Hour | Dom | Month | Dow | Descriptor,
 )
 
-// ParseStandard returns a new crontab schedule representing the given standardSpec
-// (https://en.wikipedia.org/wiki/Cron). It differs from Parse requiring to always
-// pass 5 entries representing: minute, hour, day of month, month and day of week,
-// in that order. It returns a descriptive error if the spec is not valid.
+// ParseStandard returns a new crontab schedule representing the given
+// standardSpec (https://en.wikipedia.org/wiki/Cron). It requires 5 entries
+// representing: minute, hour, day of month, month and day of week, in that
+// order. It returns a descriptive error if the spec is not valid.
 //
 // It accepts
 //   - Standard crontab specs, e.g. "* * * * ?"
@@ -171,20 +230,6 @@ func ParseStandard(standardSpec string) (Schedule, error) {
 	return standardParser.Parse(standardSpec)
 }
 
-var defaultParser = NewParser(
-	Second | Minute | Hour | Dom | Month | DowOptional | Descriptor,
-)
-
-// Parse returns a new crontab schedule representing the given spec.
-// It returns a descriptive error if the spec is not valid.
-//
-// It accepts
-//   - Full crontab specs, e.g. "* * * * * ?"
-//   - Descriptors, e.g. "@midnight", "@every 1h30m"
-func Parse(spec string) (Schedule, error) {
-	return defaultParser.Parse(spec)
-}
-
 // getField returns an Int with the bits set representing all of the times that
 // the field represents or error parsing field value.  A "field" is a comma-separated
 // list of "ranges".
@@ -232,7 +277,7 @@ func getRange(expr string, r bounds) (uint64, error) {
 				return 0, err
 			}
 		default:
-			return 0, fmt.Errorf("Too many hyphens: %s", expr)
+			return 0, fmt.Errorf("too many hyphens: %s", expr)
 		}
 	}
 
@@ -249,21 +294,24 @@ func getRange(expr string, r bounds) (uint64, error) {
 		if singleDigit {
 			end = r.max
 		}
+		if step > 1 {
+			extra = 0
+		}
 	default:
-		return 0, fmt.Errorf("Too many slashes: %s", expr)
+		return 0, fmt.Errorf("too many slashes: %s", expr)
 	}
 
 	if start < r.min {
-		return 0, fmt.Errorf("Beginning of range (%d) below minimum (%d): %s", start, r.min, expr)
+		return 0, fmt.Errorf("beginning of range (%d) below minimum (%d): %s", start, r.min, expr)
 	}
 	if end > r.max {
-		return 0, fmt.Errorf("End of range (%d) above maximum (%d): %s", end, r.max, expr)
+		return 0, fmt.Errorf("end of range (%d) above maximum (%d): %s", end, r.max, expr)
 	}
 	if start > end {
-		return 0, fmt.Errorf("Beginning of range (%d) beyond end of range (%d): %s", start, end, expr)
+		return 0, fmt.Errorf("beginning of range (%d) beyond end of range (%d): %s", start, end, expr)
 	}
 	if step == 0 {
-		return 0, fmt.Errorf("Step of range should be a positive number: %s", expr)
+		return 0, fmt.Errorf("step of range should be a positive number: %s", expr)
 	}
 
 	return getBits(start, end, step) | extra, nil
@@ -283,10 +331,10 @@ func parseIntOrName(expr string, names map[string]uint) (uint, error) {
 func mustParseInt(expr string) (uint, error) {
 	num, err := strconv.Atoi(expr)
 	if err != nil {
-		return 0, fmt.Errorf("Failed to parse int from %s: %s", expr, err)
+		return 0, fmt.Errorf("failed to parse int from %s: %s", expr, err)
 	}
 	if num < 0 {
-		return 0, fmt.Errorf("Negative number (%d) not allowed: %s", num, expr)
+		return 0, fmt.Errorf("negative number (%d) not allowed: %s", num, expr)
 	}
 
 	return uint(num), nil
@@ -314,67 +362,73 @@ func all(r bounds) uint64 {
 }
 
 // parseDescriptor returns a predefined schedule for the expression, or error if none matches.
-func parseDescriptor(descriptor string) (Schedule, error) {
+func parseDescriptor(descriptor string, loc *time.Location) (Schedule, error) {
 	switch descriptor {
 	case "@yearly", "@annually":
 		return &SpecSchedule{
-			Second: 1 << seconds.min,
-			Minute: 1 << minutes.min,
-			Hour:   1 << hours.min,
-			Dom:    1 << dom.min,
-			Month:  1 << months.min,
-			Dow:    all(dow),
+			Second:   1 << seconds.min,
+			Minute:   1 << minutes.min,
+			Hour:     1 << hours.min,
+			Dom:      1 << dom.min,
+			Month:    1 << months.min,
+			Dow:      all(dow),
+			Location: loc,
 		}, nil
 
 	case "@monthly":
 		return &SpecSchedule{
-			Second: 1 << seconds.min,
-			Minute: 1 << minutes.min,
-			Hour:   1 << hours.min,
-			Dom:    1 << dom.min,
-			Month:  all(months),
-			Dow:    all(dow),
+			Second:   1 << seconds.min,
+			Minute:   1 << minutes.min,
+			Hour:     1 << hours.min,
+			Dom:      1 << dom.min,
+			Month:    all(months),
+			Dow:      all(dow),
+			Location: loc,
 		}, nil
 
 	case "@weekly":
 		return &SpecSchedule{
-			Second: 1 << seconds.min,
-			Minute: 1 << minutes.min,
-			Hour:   1 << hours.min,
-			Dom:    all(dom),
-			Month:  all(months),
-			Dow:    1 << dow.min,
+			Second:   1 << seconds.min,
+			Minute:   1 << minutes.min,
+			Hour:     1 << hours.min,
+			Dom:      all(dom),
+			Month:    all(months),
+			Dow:      1 << dow.min,
+			Location: loc,
 		}, nil
 
 	case "@daily", "@midnight":
 		return &SpecSchedule{
-			Second: 1 << seconds.min,
-			Minute: 1 << minutes.min,
-			Hour:   1 << hours.min,
-			Dom:    all(dom),
-			Month:  all(months),
-			Dow:    all(dow),
+			Second:   1 << seconds.min,
+			Minute:   1 << minutes.min,
+			Hour:     1 << hours.min,
+			Dom:      all(dom),
+			Month:    all(months),
+			Dow:      all(dow),
+			Location: loc,
 		}, nil
 
 	case "@hourly":
 		return &SpecSchedule{
-			Second: 1 << seconds.min,
-			Minute: 1 << minutes.min,
-			Hour:   all(hours),
-			Dom:    all(dom),
-			Month:  all(months),
-			Dow:    all(dow),
+			Second:   1 << seconds.min,
+			Minute:   1 << minutes.min,
+			Hour:     all(hours),
+			Dom:      all(dom),
+			Month:    all(months),
+			Dow:      all(dow),
+			Location: loc,
 		}, nil
+
 	}
 
 	const every = "@every "
 	if strings.HasPrefix(descriptor, every) {
 		duration, err := time.ParseDuration(descriptor[len(every):])
 		if err != nil {
-			return nil, fmt.Errorf("Failed to parse duration %s: %s", descriptor, err)
+			return nil, fmt.Errorf("failed to parse duration %s: %s", descriptor, err)
 		}
 		return Every(duration), nil
 	}
 
-	return nil, fmt.Errorf("Unrecognized descriptor: %s", descriptor)
+	return nil, fmt.Errorf("unrecognized descriptor: %s", descriptor)
 }

vendor/github.com/robfig/cron/v3/spec.go

@@ -6,6 +6,9 @@ import "time"
 // traditional crontab specification. It is computed initially and stored as bit sets.
 type SpecSchedule struct {
 	Second, Minute, Hour, Dom, Month, Dow uint64
+
+	// Override location for this schedule.
+	Location *time.Location
 }
 
 // bounds provides a range of acceptable values (plus a map of name to value).
@@ -53,7 +56,8 @@ const (
 // Next returns the next time this schedule is activated, greater than the given
 // time.  If no time can be found to satisfy the schedule, return the zero time.
 func (s *SpecSchedule) Next(t time.Time) time.Time {
-	// General approach:
+	// General approach
+	//
 	// For Month, Day, Hour, Minute, Second:
 	// Check if the time value matches.  If yes, continue to the next field.
 	// If the field doesn't match the schedule, then increment the field until it matches.
@@ -61,6 +65,19 @@ func (s *SpecSchedule) Next(t time.Time) time.Time {
 	// of the field list (since it is necessary to re-verify previous field
 	// values)
 
+	// Convert the given time into the schedule's timezone, if one is specified.
+	// Save the original timezone so we can convert back after we find a time.
+	// Note that schedules without a time zone specified (time.Local) are treated
+	// as local to the time provided.
+	origLocation := t.Location()
+	loc := s.Location
+	if loc == time.Local {
+		loc = t.Location()
+	}
+	if s.Location != time.Local {
+		t = t.In(s.Location)
+	}
+
 	// Start at the earliest possible time (the upcoming second).
 	t = t.Add(1*time.Second - time.Duration(t.Nanosecond())*time.Nanosecond)
 
@@ -82,7 +99,7 @@ WRAP:
 		if !added {
 			added = true
 			// Otherwise, set the date at the beginning (since the current time is irrelevant).
-			t = time.Date(t.Year(), t.Month(), 1, 0, 0, 0, 0, t.Location())
+			t = time.Date(t.Year(), t.Month(), 1, 0, 0, 0, 0, loc)
 		}
 		t = t.AddDate(0, 1, 0)
 
@@ -93,12 +110,25 @@ WRAP:
 	}
 
 	// Now get a day in that month.
+	//
+	// NOTE: This causes issues for daylight savings regimes where midnight does
+	// not exist.  For example: Sao Paulo has DST that transforms midnight on
+	// 11/3 into 1am. Handle that by noticing when the Hour ends up != 0.
 	for !dayMatches(s, t) {
 		if !added {
 			added = true
-			t = time.Date(t.Year(), t.Month(), t.Day(), 0, 0, 0, 0, t.Location())
+			t = time.Date(t.Year(), t.Month(), t.Day(), 0, 0, 0, 0, loc)
 		}
 		t = t.AddDate(0, 0, 1)
+		// Notice if the hour is no longer midnight due to DST.
+		// Add an hour if it's 23, subtract an hour if it's 1.
+		if t.Hour() != 0 {
+			if t.Hour() > 12 {
+				t = t.Add(time.Duration(24-t.Hour()) * time.Hour)
+			} else {
+				t = t.Add(time.Duration(-t.Hour()) * time.Hour)
+			}
+		}
 
 		if t.Day() == 1 {
 			goto WRAP
@@ -108,7 +138,7 @@ WRAP:
 	for 1<<uint(t.Hour())&s.Hour == 0 {
 		if !added {
 			added = true
-			t = time.Date(t.Year(), t.Month(), t.Day(), t.Hour(), 0, 0, 0, t.Location())
+			t = time.Date(t.Year(), t.Month(), t.Day(), t.Hour(), 0, 0, 0, loc)
 		}
 		t = t.Add(1 * time.Hour)
 
@@ -141,7 +171,7 @@ WRAP:
 		}
 	}
 
-	return t
+	return t.In(origLocation)
 }
 
 // dayMatches returns true if the schedule's day-of-week and day-of-month

vendor/modules.txt

@@ -693,9 +693,9 @@ github.com/prometheus/procfs/internal/util
 # github.com/quobyte/api v0.1.8 => github.com/quobyte/api v0.1.8
 ## explicit
 github.com/quobyte/api
-# github.com/robfig/cron v1.1.0 => github.com/robfig/cron v1.1.0
+# github.com/robfig/cron/v3 v3.0.1 => github.com/robfig/cron/v3 v3.0.1
 ## explicit
-github.com/robfig/cron
+github.com/robfig/cron/v3
 # github.com/rubiojr/go-vhd v0.0.0-20200706105327-02e210299021 => github.com/rubiojr/go-vhd v0.0.0-20200706105327-02e210299021
 github.com/rubiojr/go-vhd/vhd
 # github.com/russross/blackfriday v1.5.2 => github.com/russross/blackfriday v1.5.2
@@ -2532,7 +2532,7 @@ sigs.k8s.io/yaml
 # github.com/prometheus/procfs => github.com/prometheus/procfs v0.2.0
 # github.com/quobyte/api => github.com/quobyte/api v0.1.8
 # github.com/remyoudompheng/bigfft => github.com/remyoudompheng/bigfft v0.0.0-20170806203942-52369c62f446
-# github.com/robfig/cron => github.com/robfig/cron v1.1.0
+# github.com/robfig/cron/v3 => github.com/robfig/cron/v3 v3.0.1
 # github.com/rogpeppe/fastuuid => github.com/rogpeppe/fastuuid v0.0.0-20150106093220-6724a57986af
 # github.com/rogpeppe/go-internal => github.com/rogpeppe/go-internal v1.3.0
 # github.com/rubiojr/go-vhd => github.com/rubiojr/go-vhd v0.0.0-20200706105327-02e210299021