docker: sync access to exit result within a handle

drivers/docker/driver.go

@@ -83,8 +83,7 @@ type Driver struct {
 	// coordinator is what tracks multiple image pulls against the same docker image
 	coordinator *dockerCoordinator
 
-	// logger will log to the plugin output which is usually an 'executor.out'
-	// file located in the root of the TaskDir
+	// logger will log to the Nomad agent
 	logger hclog.Logger
 }
 
@@ -990,7 +989,7 @@ func (d *Driver) handleWait(ctx context.Context, ch chan *drivers.ExitResult, h
 	defer close(ch)
 	select {
 	case <-h.waitCh:
-		ch <- h.exitResult
+		ch <- h.ExitResult()
 	case <-ctx.Done():
 		ch <- &drivers.ExitResult{
 			Err: ctx.Err(),
@@ -1080,7 +1079,7 @@ func (d *Driver) InspectTask(taskID string) (*drivers.TaskStatus, error) {
 			"container_id": container.ID,
 		},
 		NetworkOverride: h.net,
-		ExitResult:      h.exitResult,
+		ExitResult:      h.ExitResult(),
 	}
 
 	status.State = drivers.TaskStateUnknown

drivers/docker/handle.go

@@ -38,7 +38,14 @@ type taskHandle struct {
 	net                   *structs.DriverNetwork
 	imageID               string
 
-	exitResult *drivers.ExitResult
+	exitResult     *drivers.ExitResult
+	exitResultLock sync.Mutex
+}
+
+func (h *taskHandle) ExitResult() *drivers.ExitResult {
+	h.exitResultLock.Lock()
+	defer h.exitResultLock.Unlock()
+	return h.exitResult.Copy()
 }
 
 type taskHandleState struct {
@@ -202,12 +209,14 @@ func (h *taskHandle) run() {
 	}
 
 	// Set the result
+	h.exitResultLock.Lock()
 	h.exitResult = &drivers.ExitResult{
 		ExitCode:  exitCode,
 		Signal:    0,
 		OOMKilled: oom,
 		Err:       werr,
 	}
+	h.exitResultLock.Unlock()
 	close(h.waitCh)
 }
 

plugins/drivers/driver.go

@@ -249,6 +249,12 @@ func (r *ExitResult) Successful() bool {
 	return r.ExitCode == 0 && r.Signal == 0 && r.Err == nil
 }
 
+func (r *ExitResult) Copy() *ExitResult {
+	res := new(ExitResult)
+	*res = *r
+	return res
+}
+
 type TaskStatus struct {
 	ID               string
 	Name             string