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Merge pull request #50381 from sczizzo/bugfix-issue-47800

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Automatic merge from submit-queue (batch tested with PRs 50381, 51307, 49645, 50995, 51523)

Bugfix: Use local JSON log buffer in parseDockerJSONLog.

**What this PR does / why we need it**:
The issue described in #47800 is due to a race condition in `ReadLogs`: Because the JSON log buffer (`dockerJSONLog`) is package-scoped, any two goroutines modifying the buffer could race and overwrite the other's changes. In particular, one goroutine could unmarshal a JSON log line into the buffer, then another goroutine could `Reset()` the buffer, and the resulting `Stream` would be empty (`""`). This empty `Stream` is caught in a `case` block and raises an `unexpected stream type` error.

This PR creates a new buffer for each execution of `parseDockerJSONLog`, so each goroutine is guaranteed to have a local instance of the buffer.

**Which issue this PR fixes**: fixes #47800

**Release note**:
```release-note
Fixed an issue (#47800) where `kubectl logs -f` failed with `unexpected stream type ""`.
```
This commit is contained in:
Kubernetes Submit Queue 2017-09-01 16:33:56 -07:00 committed by GitHub
commit 0955f3602e
1 changed files with 3 additions and 5 deletions
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8
pkg/kubelet/kuberuntime/kuberuntime_logs.go
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@ -280,16 +280,14 @@ func parseCRILog(log []byte, msg *logMessage) error {
return nil
}
// dockerJSONLog is the JSON log buffer used in parseDockerJSONLog.
var dockerJSONLog = &jsonlog.JSONLog{}
// parseDockerJSONLog parses logs in Docker JSON log format. Docker JSON log format
// example:
// {"log":"content 1","stream":"stdout","time":"2016-10-20T18:39:20.57606443Z"}
// {"log":"content 2","stream":"stderr","time":"2016-10-20T18:39:20.57606444Z"}
func parseDockerJSONLog(log []byte, msg *logMessage) error {
dockerJSONLog.Reset()
l := dockerJSONLog
var l = &jsonlog.JSONLog{}
l.Reset()
// TODO: JSON decoding is fairly expensive, we should evaluate this.
if err := json.Unmarshal(log, l); err != nil {
return fmt.Errorf("failed with %v to unmarshal log %q", err, l)