mirror of
https://github.com/kubernetes/client-go.git
synced 2025-09-01 15:17:19 +00:00
chore(*): update election example (#82821)
* feat(*): simplify leader election example * chore(*): fix with comment * chore(*): add os.exit * chore(*): fix typo Kubernetes-commit: 1185012da65edf802f22aff24141c0466a2a3ac8
This commit is contained in:
Mengjiang Bao
committed by
Kubernetes Publisher
Kubernetes Publisher
parent
172b42569c
commit
c51c673cf8
2
Godeps/Godeps.json
generated
2
Godeps/Godeps.json
generated
@@ -348,7 +348,7 @@
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},
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{
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"ImportPath": "k8s.io/apimachinery",
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"Rev": "f9f2f3f8ab02"
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"Rev": "fb3eea214746"
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},
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{
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"ImportPath": "k8s.io/gengo",
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@@ -8,14 +8,15 @@ Run the following three commands in separate terminals. Each terminal needs a un
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```bash
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# first terminal
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go run *.go -kubeconfig=/my/config -logtostderr=true -id=1
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go run main.go -kubeconfig=/path/to/kubeconfig -logtostderr=true -lease-lock-name=example -lease-lock-namespace=default -id=1
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# second terminal
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go run *.go -kubeconfig=/my/config -logtostderr=true -id=2
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go run main.go -kubeconfig=/path/to/kubeconfig -logtostderr=true -lease-lock-name=example -lease-lock-namespace=default -id=2
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# third terminal
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go run *.go -kubeconfig=/my/config -logtostderr=true -id=3
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go run main.go -kubeconfig=/path/to/kubeconfig -logtostderr=true -lease-lock-name=example -lease-lock-namespace=default -id=3
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```
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> You can ignore the `-kubeconfig` flag if you are running these commands in the Kubernetes cluster.
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Now kill the existing leader. You will see from the terminal outputs that one of the remaining two processes will be elected as the new leader.
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@@ -19,21 +19,18 @@ package main
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import (
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"context"
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"flag"
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"fmt"
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"log"
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"os"
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"os/signal"
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"strings"
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"syscall"
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"time"
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"github.com/google/uuid"
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metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
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clientset "k8s.io/client-go/kubernetes"
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"k8s.io/client-go/rest"
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"k8s.io/client-go/tools/clientcmd"
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"k8s.io/client-go/tools/leaderelection"
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"k8s.io/client-go/tools/leaderelection/resourcelock"
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"k8s.io/client-go/transport"
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"k8s.io/klog"
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)
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@@ -62,13 +59,16 @@ func main() {
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var id string
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flag.StringVar(&kubeconfig, "kubeconfig", "", "absolute path to the kubeconfig file")
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flag.StringVar(&id, "id", "", "the holder identity name")
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flag.StringVar(&leaseLockName, "lease-lock-name", "example", "the lease lock resource name")
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flag.StringVar(&leaseLockNamespace, "lease-lock-namespace", "default", "the lease lock resource namespace")
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flag.StringVar(&id, "id", uuid.New().String(), "the holder identity name")
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flag.StringVar(&leaseLockName, "lease-lock-name", "", "the lease lock resource name")
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flag.StringVar(&leaseLockNamespace, "lease-lock-namespace", "", "the lease lock resource namespace")
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flag.Parse()
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if id == "" {
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klog.Fatal("unable to get id (missing id flag).")
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if leaseLockName == "" {
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klog.Fatal("unable to get lease lock resource name (missing lease-lock-name flag).")
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}
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if leaseLockNamespace == "" {
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klog.Fatal("unable to get lease lock resource namespace (missing lease-lock-namespace flag).")
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}
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// leader election uses the Kubernetes API by writing to a
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@@ -82,6 +82,29 @@ func main() {
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}
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client := clientset.NewForConfigOrDie(config)
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run := func(ctx context.Context) {
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// complete your controller loop here
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klog.Info("Controller loop...")
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select {}
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}
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// use a Go context so we can tell the leaderelection code when we
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// want to step down
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ctx, cancel := context.WithCancel(context.Background())
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defer cancel()
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// listen for interrupts or the Linux SIGTERM signal and cancel
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// our context, which the leader election code will observe and
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// step down
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ch := make(chan os.Signal, 1)
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signal.Notify(ch, os.Interrupt, syscall.SIGTERM)
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go func() {
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<-ch
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klog.Info("Received termination, signaling shutdown")
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cancel()
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}()
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// we use the Lease lock type since edits to Leases are less common
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// and fewer objects in the cluster watch "all Leases".
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lock := &resourcelock.LeaseLock{
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@@ -95,25 +118,6 @@ func main() {
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},
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}
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// use a Go context so we can tell the leaderelection code when we
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// want to step down
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ctx, cancel := context.WithCancel(context.Background())
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defer cancel()
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// use a client that will stop allowing new requests once the context ends
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config.Wrap(transport.ContextCanceller(ctx, fmt.Errorf("the leader is shutting down")))
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// listen for interrupts or the Linux SIGTERM signal and cancel
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// our context, which the leader election code will observe and
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// step down
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ch := make(chan os.Signal, 1)
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signal.Notify(ch, os.Interrupt, syscall.SIGTERM)
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go func() {
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<-ch
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log.Printf("Received termination, signaling shutdown")
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cancel()
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}()
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// start the leader election code loop
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leaderelection.RunOrDie(ctx, leaderelection.LeaderElectionConfig{
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Lock: lock,
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@@ -131,12 +135,12 @@ func main() {
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OnStartedLeading: func(ctx context.Context) {
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// we're notified when we start - this is where you would
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// usually put your code
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klog.Infof("%s: leading", id)
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run(ctx)
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},
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OnStoppedLeading: func() {
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// we can do cleanup here, or after the RunOrDie method
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// returns
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klog.Infof("%s: lost", id)
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// we can do cleanup here
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klog.Infof("leader lost: %s", id)
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os.Exit(0)
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},
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OnNewLeader: func(identity string) {
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// we're notified when new leader elected
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@@ -144,18 +148,8 @@ func main() {
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// I just got the lock
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return
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}
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klog.Infof("new leader elected: %v", identity)
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klog.Infof("new leader elected: %s", identity)
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},
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},
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})
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// because the context is closed, the client should report errors
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_, err = client.CoordinationV1().Leases(leaseLockNamespace).Get(leaseLockName, metav1.GetOptions{})
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if err == nil || !strings.Contains(err.Error(), "the leader is shutting down") {
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log.Fatalf("%s: expected to get an error when trying to make a client call: %v", id, err)
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}
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// we no longer hold the lease, so perform any cleanup and then
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// exit
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log.Printf("%s: done", id)
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}
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5
go.mod
5
go.mod
@@ -14,6 +14,7 @@ require (
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github.com/golang/groupcache v0.0.0-20160516000752-02826c3e7903
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github.com/golang/protobuf v1.3.1
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github.com/google/gofuzz v1.0.0
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github.com/google/uuid v1.1.1
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github.com/googleapis/gnostic v0.0.0-20170729233727-0c5108395e2d
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github.com/gophercloud/gophercloud v0.1.0
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github.com/gregjones/httpcache v0.0.0-20170728041850-787624de3eb7
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@@ -27,7 +28,7 @@ require (
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golang.org/x/time v0.0.0-20181108054448-85acf8d2951c
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google.golang.org/appengine v1.5.0 // indirect
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k8s.io/api v0.0.0-20191010143144-fbf594f18f80
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k8s.io/apimachinery v0.0.0-20191006235458-f9f2f3f8ab02
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k8s.io/apimachinery v0.0.0-20191014065749-fb3eea214746
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k8s.io/klog v1.0.0
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k8s.io/utils v0.0.0-20190920012459-5008bf6f8cd6
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sigs.k8s.io/yaml v1.1.0
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@@ -42,5 +43,5 @@ replace (
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golang.org/x/text => golang.org/x/text v0.3.1-0.20181227161524-e6919f6577db
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golang.org/x/time => golang.org/x/time v0.0.0-20161028155119-f51c12702a4d
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k8s.io/api => k8s.io/api v0.0.0-20191010143144-fbf594f18f80
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k8s.io/apimachinery => k8s.io/apimachinery v0.0.0-20191006235458-f9f2f3f8ab02
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k8s.io/apimachinery => k8s.io/apimachinery v0.0.0-20191014065749-fb3eea214746
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)
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3
go.sum
3
go.sum
@@ -64,6 +64,7 @@ github.com/google/gofuzz v1.0.0 h1:A8PeW59pxE9IoFRqBp37U+mSNaQoZ46F1f0f863XSXw=
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github.com/google/gofuzz v1.0.0/go.mod h1:dBl0BpW6vV/+mYPU4Po3pmUjxk6FQPldtuIdl/M65Eg=
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github.com/google/martian v2.1.0+incompatible/go.mod h1:9I4somxYTbIHy5NJKHRl3wXiIaQGbYVAs8BPL6v8lEs=
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github.com/google/pprof v0.0.0-20181206194817-3ea8567a2e57/go.mod h1:zfwlbNMJ+OItoe0UupaVj+oy1omPYYDuagoSzA8v9mc=
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github.com/google/uuid v1.1.1 h1:Gkbcsh/GbpXz7lPftLA3P6TYMwjCLYm83jiFQZF/3gY=
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github.com/google/uuid v1.1.1/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
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github.com/googleapis/gax-go/v2 v2.0.4/go.mod h1:0Wqv26UfaUD9n4G6kQubkQ+KchISgw+vpHVxEJEs9eg=
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github.com/googleapis/gnostic v0.0.0-20170729233727-0c5108395e2d h1:7XGaL1e6bYS1yIonGp9761ExpPPV1ui0SAC59Yube9k=
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@@ -180,7 +181,7 @@ gopkg.in/yaml.v2 v2.2.4/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
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honnef.co/go/tools v0.0.0-20190102054323-c2f93a96b099/go.mod h1:rf3lG4BRIbNafJWhAfAdb/ePZxsR/4RtNHQocxwk9r4=
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honnef.co/go/tools v0.0.0-20190106161140-3f1c8253044a/go.mod h1:rf3lG4BRIbNafJWhAfAdb/ePZxsR/4RtNHQocxwk9r4=
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k8s.io/api v0.0.0-20191010143144-fbf594f18f80/go.mod h1:X3kixOyiuC4u4LU6y2BxLg5tsvw+hrMhstfga7LZ4Gw=
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k8s.io/apimachinery v0.0.0-20191006235458-f9f2f3f8ab02/go.mod h1:92mWDd8Ji2sw2157KIgino5wCxffA8KSvhW2oY4ypdw=
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k8s.io/apimachinery v0.0.0-20191014065749-fb3eea214746/go.mod h1:92mWDd8Ji2sw2157KIgino5wCxffA8KSvhW2oY4ypdw=
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k8s.io/gengo v0.0.0-20190128074634-0689ccc1d7d6/go.mod h1:ezvh/TsK7cY6rbqRK0oQQ8IAqLxYwwyPxAX1Pzy0ii0=
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k8s.io/klog v0.0.0-20181102134211-b9b56d5dfc92/go.mod h1:Gq+BEi5rUBO/HRz0bTSXDUcqjScdoY3a9IHpCEIOOfk=
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k8s.io/klog v0.3.0/go.mod h1:Gq+BEi5rUBO/HRz0bTSXDUcqjScdoY3a9IHpCEIOOfk=
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