Merge pull request #31378 from yifan-gu/rkt_fetch_no_store

Automatic merge from submit-queue rkt: Force `rkt fetch` to fetch from remote to conform the image pull policy. Fix https://github.com/kubernetes/kubernetes/issues/27646 Use `--no-store` option for `rkt fetch` to force it to fetch from remote. However, `--no-store` will fetch the remote image regardless of whether the content of the image has changed or not. This causes performance downgrade when the image tag is ':latest' and the image pull policy is 'always'. The issue is tracked in https://github.com/coreos/rkt/issues/2937.

Merge pull request #31378 from yifan-gu/rkt_fetch_no_store
9deb18b9 · Kubernetes Submit Queue · GitHub · a9754114 · de402ac2 · 9deb18b9
Commit 9deb18b9 authored Aug 26, 2016 by Kubernetes Submit Queue Committed by GitHub Aug 26, 2016
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image.go pkg/kubelet/rkt/image.go +4 -1

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--- a/pkg/kubelet/rkt/image.go
+++ b/pkg/kubelet/rkt/image.go
@@ -76,7 +76,10 @@ func (r *Runtime) PullImage(image kubecontainer.ImageSpec, pullSecrets []api.Sec
 		return err
 	}

-	if _, err := r.cli.RunCommand(&config, "fetch", dockerPrefix+img); err != nil {
+	// Today, `--no-store` will fetch the remote image regardless of whether the content of the image
+	// has changed or not. This causes performance downgrades when the image tag is ':latest' and
+	// the image pull policy is 'always'. The issue is tracked in https://github.com/coreos/rkt/issues/2937.
+	if _, err := r.cli.RunCommand(&config, "fetch", "--no-store", dockerPrefix+img); err != nil {
 		glog.Errorf("Failed to fetch: %v", err)
 		return err
 	}