fix: agentcontainers: fix flake when ctx cancelled while running docker inspect

johnstcn · johnstcn · commit c9d3b2c2d03a · 2025-06-24T12:12:36.000+01:00
diff --git a/agent/agentcontainers/api.go b/agent/agentcontainers/api.go
@@ -378,7 +378,11 @@ func (api *API) updaterLoop() {
 	// and anyone looking to interact with the API.
 	api.logger.Debug(api.ctx, "performing initial containers update")
 	if err := api.updateContainers(api.ctx); err != nil {
-		api.logger.Error(api.ctx, "initial containers update failed", slog.Error(err))
+		if errors.Is(err, context.Canceled) {
+			api.logger.Warn(api.ctx, "initial containers update canceled", slog.Error(err))
+		} else {
+			api.logger.Error(api.ctx, "initial containers update failed", slog.Error(err))
+		}
 	} else {
 		api.logger.Debug(api.ctx, "initial containers update complete")
 	}
@@ -399,7 +403,11 @@ func (api *API) updaterLoop() {
 		case api.updateTrigger <- done:
 			err := <-done
 			if err != nil {
-				api.logger.Error(api.ctx, "updater loop ticker failed", slog.Error(err))
+				if errors.Is(err, context.Canceled) {
+					api.logger.Warn(api.ctx, "updater loop ticker canceled", slog.Error(err))
+				} else {
+					api.logger.Error(api.ctx, "updater loop ticker failed", slog.Error(err))
+				}
 			}
 		default:
 			api.logger.Debug(api.ctx, "updater loop ticker skipped, update in progress")
diff --git a/agent/agentcontainers/containers_dockercli.go b/agent/agentcontainers/containers_dockercli.go
@@ -311,21 +311,31 @@ func (dcli *dockerCLI) List(ctx context.Context) (codersdk.WorkspaceAgentListCon
 // container IDs and returns the parsed output.
 // The stderr output is also returned for logging purposes.
 func runDockerInspect(ctx context.Context, execer agentexec.Execer, ids ...string) (stdout, stderr []byte, err error) {
-	var stdoutBuf, stderrBuf bytes.Buffer
-	cmd := execer.CommandContext(ctx, "docker", append([]string{"inspect"}, ids...)...)
-	cmd.Stdout = &stdoutBuf
-	cmd.Stderr = &stderrBuf
-	err = cmd.Run()
-	stdout = bytes.TrimSpace(stdoutBuf.Bytes())
-	stderr = bytes.TrimSpace(stderrBuf.Bytes())
-	if err != nil {
-		if bytes.Contains(stderr, []byte("No such object:")) {
-			// This can happen if a container is deleted between the time we check for its existence and the time we inspect it.
-			return stdout, stderr, nil
+	select {
+	case <-ctx.Done():
+		// If the context is done, we don't want to run the command.
+		return []byte{}, []byte{}, ctx.Err()
+	default:
+		var stdoutBuf, stderrBuf bytes.Buffer
+		cmd := execer.CommandContext(ctx, "docker", append([]string{"inspect"}, ids...)...)
+		cmd.Stdout = &stdoutBuf
+		cmd.Stderr = &stderrBuf
+		err = cmd.Run()
+		stdout = bytes.TrimSpace(stdoutBuf.Bytes())
+		stderr = bytes.TrimSpace(stderrBuf.Bytes())
+		if err != nil {
+			if ctx.Err() != nil {
+				// If the context was canceled, we don't want to return an error.
+				return stdout, stderr, ctx.Err()
+			}
+			if bytes.Contains(stderr, []byte("No such object:")) {
+				// This can happen if a container is deleted between the time we check for its existence and the time we inspect it.
+				return stdout, stderr, nil
+			}
+			return stdout, stderr, err
 		}
-		return stdout, stderr, err
+		return stdout, stderr, nil
 	}
-	return stdout, stderr, nil
 }
 
 // To avoid a direct dependency on the Docker API, we use the docker CLI
