Support for fzf, color ignore/force knobs

Signed-off-by: Ahmet Alp Balkan <ahmetb@google.com>

cmd/kubectx/flags.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"io"
+	"os"
 	"strings"
 
 	"github.com/pkg/errors"
@@ -22,6 +23,9 @@ func (op UnsupportedOp) Run(_, _ io.Writer) error {
 // and decides which operation should be taken.
 func parseArgs(argv []string) Op {
 	if len(argv) == 0 {
+		if isInteractiveMode(os.Stdout){
+			return InteractiveSwitchOp{SelfCmd: os.Args[0]}
+		}
 		return ListOp{}
 	}
 

cmd/kubectx/fzf.go

@@ -0,0 +1,69 @@
+package main
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"os"
+	"os/exec"
+	"strings"
+
+	"github.com/pkg/errors"
+
+	"github.com/mattn/go-isatty"
+)
+
+const (
+	envFZFIgnore = "KUBECTX_IGNORE_FZF"
+)
+
+type InteractiveSwitchOp struct {
+	SelfCmd string
+}
+
+func (op InteractiveSwitchOp) Run(_, stderr io.Writer) error {
+	cmd := exec.Command("fzf", "--ansi", "--no-preview")
+	var out bytes.Buffer
+	cmd.Stdin = os.Stdin
+	cmd.Stderr = stderr
+	cmd.Stdout = &out
+
+	cmd.Env = append(os.Environ(),
+		fmt.Sprintf("FZF_DEFAULT_COMMAND=%s", op.SelfCmd),
+		fmt.Sprintf("%s=1", envForceColor))
+	if err := cmd.Run(); err != nil {
+		if _, ok := err.(*exec.ExitError); !ok {
+			return err
+		}
+	}
+	choice := strings.TrimSpace(out.String())
+	if choice == "" {
+		return errors.New("you did not choose any of the options")
+	}
+	name, err := switchContext(choice)
+	if err != nil {
+		return errors.Wrap(err, "failed to switch context")
+	}
+	printSuccess(stderr, "Switched to context %q.", name)
+	return nil
+}
+
+// isTerminal determines if given fd is a TTY.
+func isTerminal(fd *os.File) bool {
+	return isatty.IsTerminal(fd.Fd())
+}
+
+// fzfInstalled determines if fzf(1) is in PATH.
+func fzfInstalled() bool {
+	v, _ := exec.LookPath("fzf")
+	if v != "" {
+		return true
+	}
+	return false
+}
+
+// isInteractiveMode determines if we can do choosing with fzf.
+func isInteractiveMode(stdout *os.File) bool {
+	v := os.Getenv(envFZFIgnore)
+	return v == "" && isTerminal(stdout) && fzfInstalled()
+}

cmd/kubectx/list.go

@@ -3,6 +3,7 @@ package main
 import (
 	"fmt"
 	"io"
+	"os"
 
 	"facette.io/natsort"
 	"github.com/fatih/color"
@@ -11,16 +12,6 @@ import (
 	"github.com/ahmetb/kubectx/cmd/kubectx/kubeconfig"
 )
 
-type context struct {
-	Name string `yaml:"name"`
-}
-
-type kubeconfigContents struct {
-	APIVersion     string    `yaml:"apiVersion"`
-	CurrentContext string    `yaml:"current-context"`
-	Contexts       []context `yaml:"contexts"`
-}
-
 // ListOp describes listing contexts.
 type ListOp struct{}
 
@@ -36,13 +27,35 @@ func (_ ListOp) Run(stdout, _ io.Writer) error {
 
 	// TODO support KUBECTX_CURRENT_FGCOLOR
 	// TODO support KUBECTX_CURRENT_BGCOLOR
+
+	currentColor := color.New(color.FgGreen, color.Bold)
+	if useColors(){
+		currentColor.EnableColor()
+	} else {
+		currentColor.DisableColor()
+	}
+
 	cur :=  kc.GetCurrentContext()
 	for _, c := range ctxs {
 		s := c
 		if c == cur {
-			s = color.New(color.FgGreen, color.Bold).Sprint(c)
+			s = currentColor.Sprint(c)
 		}
 		fmt.Fprintf(stdout, "%s\n", s)
 	}
 	return nil
 }
+
+const (
+	envForceColor = `_KUBECTX_FORCE_COLOR`
+	envNoColor = `NO_COLOR`
+)
+
+func useColors() bool {
+	if os.Getenv(envForceColor) != "" {
+		return true
+	} else if os.Getenv(envNoColor) != "" {
+		return false
+	}
+	return true
+}

go.mod

@@ -6,6 +6,8 @@ require (
 	facette.io/natsort v0.0.0-20181210072756-2cd4dd1e2dcb
 	github.com/fatih/color v1.9.0
 	github.com/google/go-cmp v0.4.0
+	github.com/mattn/go-isatty v0.0.12
+	github.com/mattn/go-tty v0.0.3 // indirect
 	github.com/pkg/errors v0.9.1
 	gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c
 )

go.sum

@@ -7,13 +7,25 @@ github.com/google/go-cmp v0.4.0/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/
 github.com/mattn/go-colorable v0.1.4 h1:snbPLB8fVfU9iwbbo30TPtbLRzwWu6aJS6Xh4eaaviA=
 github.com/mattn/go-colorable v0.1.4/go.mod h1:U0ppj6V5qS13XJ6of8GYAs25YV2eR4EVcfRqFIhoBtE=
 github.com/mattn/go-isatty v0.0.8/go.mod h1:Iq45c/XA43vh69/j3iqttzPXn0bhXyGjM0Hdxcsrc5s=
+github.com/mattn/go-isatty v0.0.10/go.mod h1:qgIWMr58cqv1PHHyhnkY9lrL7etaEgOFcMEpPG5Rm84=
 github.com/mattn/go-isatty v0.0.11 h1:FxPOTFNqGkuDUGi3H/qkUbQO4ZiBa2brKq5r0l8TGeM=
 github.com/mattn/go-isatty v0.0.11/go.mod h1:PhnuNfih5lzO57/f3n+odYbM4JtupLOxQOAqxQCu2WE=
+github.com/mattn/go-isatty v0.0.12 h1:wuysRhFDzyxgEmMf5xjvJ2M9dZoWAXNNr5LSBS7uHXY=
+github.com/mattn/go-isatty v0.0.12/go.mod h1:cbi8OIDigv2wuxKPP5vlRcQ1OAZbq2CE4Kysco4FUpU=
+github.com/mattn/go-runewidth v0.0.6/go.mod h1:H031xJmbD/WCDINGzjvQ9THkh0rPKHF+m2gUSrubnMI=
+github.com/mattn/go-tty v0.0.3 h1:5OfyWorkyO7xP52Mq7tB36ajHDG5OHrmBGIS/DtakQI=
+github.com/mattn/go-tty v0.0.3/go.mod h1:ihxohKRERHTVzN+aSVRwACLCeqIoZAWpoICkkvrWyR0=
 github.com/pkg/errors v0.9.1 h1:FEBLx1zS214owpjy7qsBeixbURkuhQAwrK5UwLGTwt4=
 github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
+golang.org/x/sync v0.0.0-20190911185100-cd5d95a43a6e/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sys v0.0.0-20190222072716-a9d3bda3a223/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/sys v0.0.0-20191008105621-543471e840be/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20191026070338-33540a1f6037 h1:YyJpGZS1sBuBCzLAR1VEpK193GlqGZbnPFnPV/5Rsb4=
 golang.org/x/sys v0.0.0-20191026070338-33540a1f6037/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20191120155948-bd437916bb0e h1:N7DeIrjYszNmSW409R3frPPwglRwMkXSBzwVbkOjLLA=
+golang.org/x/sys v0.0.0-20191120155948-bd437916bb0e/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20200116001909-b77594299b42 h1:vEOn+mP2zCOVzKckCZy6YsCtDblrpj/w7B9nxGNELpg=
+golang.org/x/sys v0.0.0-20200116001909-b77594299b42/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c h1:dUUwHk2QECo/6vqA44rthZ8ie2QXMNeKRTHCNY2nXvo=