aws · rix0rrr · Apr 28, 2026
diff --git a/packages/aws-cdk/lib/cli/cli-config.ts b/packages/aws-cdk/lib/cli/cli-config.ts
@@ -28,6 +28,7 @@ export async function makeConfig(): Promise<CliConfig> {
       'lookups': { type: 'boolean', desc: 'Perform context lookups (synthesis fails if this is disabled and context lookups need to be performed)', default: true },
       'ignore-errors': { type: 'boolean', default: false, desc: 'Ignores synthesis errors, which will likely produce an invalid output' },
       'json': { type: 'boolean', alias: 'j', desc: 'Use JSON output instead of YAML when templates are printed to STDOUT', default: false },
+      'jsonlog': { type: 'boolean', alias: 'J', desc: 'Print log output in JSON-lines format to stderr', default: false },
       'verbose': { type: 'boolean', alias: 'v', desc: 'Show debug logs (specify multiple times to increase verbosity)', default: false, count: true },
       'debug': { type: 'boolean', desc: 'Debug the CDK app. Log additional information during synthesis, such as creation stack traces of tokens (sets CDK_DEBUG, will slow down synthesis)', default: false },
       'profile': { type: 'string', desc: 'Use the indicated AWS profile as the default environment', requiresArg: true },

diff --git a/packages/aws-cdk/lib/cli/cli-type-registry.json b/packages/aws-cdk/lib/cli/cli-type-registry.json
@@ -44,6 +44,12 @@
       "desc": "Use JSON output instead of YAML when templates are printed to STDOUT",
       "default": false
     },
+    "jsonlog": {
+      "type": "boolean",
+      "alias": "J",
+      "desc": "Print log output in JSON-lines format to stderr",
+      "default": false
+    },
     "verbose": {
       "type": "boolean",
       "alias": "v",

diff --git a/packages/aws-cdk/lib/cli/cli.ts b/packages/aws-cdk/lib/cli/cli.ts
@@ -80,6 +80,7 @@ export async function exec(args: string[], synthesizer?: Synthesizer): Promise<n
     currentAction: cmd,
     stackProgress: argv.progress,
     autoRespond: argv.yes,
+    printAsJson: argv.jsonlog,
   }, true);
   const ioHelper = asIoHelper(ioHost, ioHost.currentAction as any);
 

diff --git a/packages/aws-cdk/lib/cli/convert-to-user-input.ts b/packages/aws-cdk/lib/cli/convert-to-user-input.ts
@@ -18,6 +18,7 @@ export function convertYargsToUserInput(args: any): UserInput {
     lookups: args.lookups,
     ignoreErrors: args.ignoreErrors,
     json: args.json,
+    jsonlog: args.jsonlog,
     verbose: args.verbose,
     debug: args.debug,
     profile: args.profile,
@@ -352,6 +353,7 @@ export function convertConfigToUserInput(config: any): UserInput {
     lookups: config.lookups,
     ignoreErrors: config.ignoreErrors,
     json: config.json,
+    jsonlog: config.jsonlog,
     verbose: config.verbose,
     debug: config.debug,
     profile: config.profile,

diff --git a/packages/aws-cdk/lib/cli/io-host/cli-io-host.ts b/packages/aws-cdk/lib/cli/io-host/cli-io-host.ts
@@ -96,6 +96,13 @@ export interface CliIoHostProps {
    * @default false
    */
   readonly autoRespond?: boolean;
+
+  /**
+   * Print output as JSON instead of as human-readable text
+   *
+   * @default false
+   */
+  readonly printAsJson?: boolean;
 }
 
 /**
@@ -176,7 +183,7 @@ export class CliIoHost implements IIoHost {
   private readonly corkedLoggingBuffer: IoMessage<unknown>[] = [];
 
   private readonly autoRespond: boolean;
-
+  private readonly printAsJson: boolean;
   public telemetry?: TelemetrySession;
 
   private constructor(props: CliIoHostProps = {}) {
@@ -187,6 +194,7 @@ export class CliIoHost implements IIoHost {
     this.requireDeployApproval = props.requireDeployApproval ?? RequireApproval.BROADENING;
     this.stackProgress = props.stackProgress ?? StackActivityProgress.BAR;
     this.autoRespond = props.autoRespond ?? false;
+    this.printAsJson = props.printAsJson ?? false;
   }
 
   public async startTelemetry(args: any, context: Context, proxyAgent?: Agent) {
@@ -254,14 +262,20 @@ export class CliIoHost implements IIoHost {
    * Gets the stackProgress value.
    *
    * This takes into account other state of the ioHost,
-   * like if isTTY and isCI.
+   * like `isTTY`, `isCI` and `printAsJson`.
    */
   public get stackProgress(): StackActivityProgress {
     // We can always use EVENTS
     if (this._progress === StackActivityProgress.EVENTS) {
       return this._progress;
     }
 
+    // If we're doing machine-readable output, we're not going to do
+    // live-updating ANSI characters.
+    if (this.printAsJson) {
+      return StackActivityProgress.EVENTS;
+    }
+
     // if a debug message (and thus any more verbose messages) are relevant to the current log level, we have verbose logging
     const verboseLogging = isMessageRelevantForLevel({ level: 'debug' }, this.logLevel);
     if (verboseLogging) {
@@ -397,6 +411,11 @@ export class CliIoHost implements IIoHost {
    * Determines the output stream, based on message and configuration.
    */
   private selectStream(msg: IoMessage<any>): NodeJS.WriteStream | undefined {
+    if (this.printAsJson) {
+      // JSON output always goes to stderr
+      return process.stderr;
+    }
+
     if (isNoticesMessage(msg)) {
       return targetStreamObject(this.noticesDestination);
     }
@@ -520,6 +539,10 @@ export class CliIoHost implements IIoHost {
    * Formats a message for console output with optional color support
    */
   private formatMessage(msg: IoMessage<unknown>): string {
+    if (this.printAsJson) {
+      return `${JSON.stringify(msg)}\n`;
+    }
+
     // apply provided style or a default style if we're in TTY mode
     let message_text = this.isTTY
       ? styleMap[msg.level](msg.message)

diff --git a/packages/aws-cdk/lib/cli/parse-command-line-arguments.ts b/packages/aws-cdk/lib/cli/parse-command-line-arguments.ts
@@ -63,6 +63,12 @@ export function parseCommandLineArguments(args: Array<string>): any {
       alias: 'j',
       desc: 'Use JSON output instead of YAML when templates are printed to STDOUT',
     })
+    .option('jsonlog', {
+      default: false,
+      type: 'boolean',
+      alias: 'J',
+      desc: 'Print log output in JSON-lines format to stderr',
+    })
     .option('verbose', {
       default: false,
       type: 'boolean',

diff --git a/packages/aws-cdk/lib/cli/user-input.ts b/packages/aws-cdk/lib/cli/user-input.ts
@@ -219,6 +219,13 @@ export interface GlobalOptions {
    */
   readonly json?: boolean;
 
+  /**
+   * Print log output in JSON-lines format to stderr
+   *
+   * @default - false
+   */
+  readonly jsonlog?: boolean;
+
   /**
    * Show debug logs (specify multiple times to increase verbosity)
    *

diff --git a/packages/aws-cdk/test/cli/cli-arguments.test.ts b/packages/aws-cdk/test/cli/cli-arguments.test.ts
@@ -24,12 +24,15 @@ describe('yargs', () => {
         roleArn: undefined,
         staging: true,
         strict: undefined,
+        telemetryFile: undefined,
         verbose: 1,
         versionReporting: undefined,
         ci: true,
+        color: undefined,
         debug: false,
         ec2creds: undefined,
         json: false,
+        jsonlog: false,
         lookups: true,
         trace: undefined,
         unstable: [],
@@ -50,6 +53,9 @@ describe('yargs', () => {
         exclusively: undefined,
         force: false,
         hotswap: undefined,
+        hotswapEcsMaximumHealthyPercent: undefined,
+        hotswapEcsMinimumHealthyPercent: undefined,
+        hotswapEcsStabilizationTimeoutSeconds: undefined,
         hotswapFallback: undefined,
         ignoreNoStacks: false,
         importExistingResources: false,