add close chan to avoid unwanted retries

builder/amazon/common/ssm_driver.go

@@ -39,6 +39,7 @@ type SSMDriver struct {
 
 	retryConnection       chan bool
 	retryAfterTermination chan bool
+	closeRetryPolling     chan bool
 	wg                    sync.WaitGroup
 }
 
@@ -63,25 +64,28 @@ func (d *SSMDriver) StartSession(ctx context.Context, input ssm.StartSessionInpu
 
 	d.retryConnection = make(chan bool, 1)
 	d.retryAfterTermination = make(chan bool, 1)
-	// Starts go routine that will keep listening to a retry channel and retry the session creation when needed.
-	// The log polling process will add data to the retry channel whenever a retryable error happens to session.
+	d.closeRetryPolling = make(chan bool, 1)
+	// Starts go routine that will keep listening to channels and retry the session creation/connection when needed.
+	// The log polling process will add data to the channels whenever a retryable error happens to the session or if it's terminated.
 	go func(ctx context.Context, driver *SSMDriver, input ssm.StartSessionInput) {
 		for {
 			select {
 			case <-ctx.Done():
 				return
+			case ok := <-d.closeRetryPolling:
+				if ok {
+					return
+				}
 			case r := <-driver.retryAfterTermination:
 				if r {
 					d.wg.Wait()
 					log.Printf("[DEBUG] Restablishing SSM connection")
 					_, _ = driver.StartSession(ctx, input)
-					// Close channels and end goroutine. Another goroutine will start
-					// and the channels wil be reopened.
-					close(driver.retryConnection)
-					close(driver.retryAfterTermination)
+					// End this routine. Another routine will start.
 					return
 				}
 			case r := <-driver.retryConnection:
+				// Tunnel is still open an we want to try to reconnect
 				if r {
 					d.wg.Wait()
 					log.Printf("[DEBUG] Retrying to establish SSM connection")
@@ -111,6 +115,7 @@ func (d *SSMDriver) StartSession(ctx context.Context, input ssm.StartSessionInpu
 func (d *SSMDriver) StartSessionWithContext(ctx context.Context, input ssm.StartSessionInput) (*ssm.StartSessionOutput, error) {
 	d.wg.Add(1)
 	defer d.wg.Done()
+
 	var output *ssm.StartSessionOutput
 	err := retry.Config{
 		ShouldRetry: func(err error) bool { return IsAWSErr(err, "TargetNotConnected", "") },
@@ -119,6 +124,7 @@ func (d *SSMDriver) StartSessionWithContext(ctx context.Context, input ssm.Start
 		output, err = d.SvcClient.StartSessionWithContext(ctx, &input)
 		return err
 	})
+
 	return output, err
 }
 
@@ -221,6 +227,9 @@ func (d *SSMDriver) StopSession() error {
 	d.wg.Add(1)
 	defer d.wg.Done()
 
+	// Stop retry polling process to avoid unwanted retries at this point
+	d.closeRetryPolling <- true
+
 	if d.session == nil || d.session.SessionId == nil {
 		return fmt.Errorf("Unable to find a valid session to instance %q; skipping the termination step",
 			aws.StringValue(d.sessionParams.Target))
@@ -231,12 +240,9 @@ func (d *SSMDriver) StopSession() error {
 		err = fmt.Errorf("Error terminating SSM Session %q. Please terminate the session manually: %s", aws.StringValue(d.session.SessionId), err)
 	}
 
-	if d.retryConnection != nil {
-		close(d.retryConnection)
-	}
-	if d.retryAfterTermination != nil {
-		close(d.retryAfterTermination)
-	}
+	close(d.closeRetryPolling)
+	close(d.retryAfterTermination)
+	close(d.retryConnection)
 	return err
 }