fix(cli): synthesis stops on expired AWS credentials

#21052 tried to fix the situation
where we would keep on doing retries if AWS credentials were expired.

However, this is now failing too hard for people that commonly have
expired credentials in their environment but still want to have
`cdk synth` complete successfully.

Catch and swallow the error (but do complain with a warning) if we
encounter an `ExpiredToken` during the `defaultAccount` operation.
That's the only place where it's used, and the only place where the
value is optional -- it behaves the same as if no credentials were
configured.

Also in this PR: add some TypeScript decorators to trace through a bunch
of async method calls to come up with a reasonable trace of where errors
originate. Not complete, not intended to be. But it is a nice basis
for debugging SDK call behavior, and can be used more in the future.

packages/aws-cdk/lib/api/aws-auth/sdk-provider.ts

@@ -4,6 +4,7 @@ import * as cxapi from '@aws-cdk/cx-api';
 import * as AWS from 'aws-sdk';
 import type { ConfigurationOptions } from 'aws-sdk/lib/config-base';
 import * as fs from 'fs-extra';
+import { traceMethods } from '../../util/tracing';
 import { debug, warning } from './_env';
 import { AwsCliCompatible } from './awscli-compatible';
 import { cached } from './cached';
@@ -127,6 +128,7 @@ export interface SdkForEnvironment {
  *     - Seeded terminal with `ReadOnly` credentials in order to do `cdk diff`--the `ReadOnly`
  *       role doesn't have `sts:AssumeRole` and will fail for no real good reason.
  */
+@traceMethods
 export class SdkProvider {
   /**
    * Create a new SdkProvider which gets its defaults in a way that behaves like the AWS CLI does
@@ -279,11 +281,15 @@ export class SdkProvider {
 
         return await new SDK(creds, this.defaultRegion, this.sdkOptions).currentAccount();
       } catch (e) {
-        if (isUnrecoverableAwsError(e)) {
-          throw e;
+        // Treat 'ExpiredToken' specially. This is a common situation that people may find themselves in, and
+        // they are complaining about if we fail 'cdk synth' on them. We loudly complain in order to show that
+        // the current situation is probably undesirable, but we don't fail.
+        if ((e as any).code === 'ExpiredToken') {
+          warning('There are expired AWS credentials in your environment. The CDK app will synth without current account information.');
+          return undefined;
         }
 
-        debug('Unable to determine the default AWS account:', e);
+        debug(`Unable to determine the default AWS account (${e.code}): ${e.message}`);
         return undefined;
       }
     });

packages/aws-cdk/lib/api/aws-auth/sdk.ts

@@ -1,5 +1,6 @@
 import * as AWS from 'aws-sdk';
 import type { ConfigurationOptions } from 'aws-sdk/lib/config-base';
+import { traceMethods } from '../../util/tracing';
 import { debug, trace } from './_env';
 import { AccountAccessKeyCache } from './account-cache';
 import { cached } from './cached';
@@ -81,6 +82,7 @@ export interface SdkOptions {
 /**
  * Base functionality of SDK without credential fetching
  */
+@traceMethods
 export class SDK implements ISDK {
   private static readonly accountCache = new AccountAccessKeyCache();
 

packages/aws-cdk/lib/cli.ts

@@ -24,6 +24,7 @@ import { displayNotices, refreshNotices } from '../lib/notices';
 import { Command, Configuration, Settings } from '../lib/settings';
 import * as version from '../lib/version';
 import { DeploymentMethod } from './api';
+import { enableTracing } from './util/tracing';
 
 // https://github.com/yargs/yargs/issues/1929
 // https://github.com/evanw/esbuild/issues/1492
@@ -281,6 +282,10 @@ async function initCommandLine() {
   const argv = await parseCommandLineArguments();
   if (argv.verbose) {
     setLogLevel(argv.verbose);
+
+    if (argv.verbose > 2) {
+      enableTracing(true);
+    }
   }
 
   if (argv.ci) {

packages/aws-cdk/lib/util/tracing.ts

@@ -0,0 +1,53 @@
+import { debug } from '../logging';
+
+let ENABLED = false;
+let INDENT = 0;
+
+export function enableTracing(enabled: boolean) {
+  ENABLED = enabled;
+}
+
+/**
+ * Method decorator to trace a single static or member method, any time it's called
+ */
+export function traceCall(receiver: object, _propertyKey: string, descriptor: PropertyDescriptor, parentClassName?: string) {
+  const fn = descriptor.value;
+  const className = typeof receiver === 'function' ? receiver.name : parentClassName;
+
+  descriptor.value = function (...args: any[]) {
+    if (!ENABLED) { return fn.apply(this, args); }
+
+    debug(`[trace] ${' '.repeat(INDENT)}${className || this.constructor.name || '(anonymous)'}#${fn.name}()`);
+    INDENT += 2;
+
+    const ret = fn.apply(this, args);
+    if (ret instanceof Promise) {
+      return ret.finally(() => {
+        INDENT -= 2;
+      });
+    } else {
+      INDENT -= 2;
+      return ret;
+    }
+  };
+  return descriptor;
+}
+
+/**
+ * Class decorator, enable tracing for all methods on this class
+ */
+export function traceMethods(constructor: Function) {
+  // Statics
+  for (const [name, descriptor] of Object.entries(Object.getOwnPropertyDescriptors(constructor))) {
+    if (typeof descriptor.value !== 'function') { continue; }
+    const newDescriptor = traceCall(constructor, name, descriptor, constructor.name) ?? descriptor;
+    Object.defineProperty(constructor, name, newDescriptor);
+  }
+
+  // Instancne members
+  for (const [name, descriptor] of Object.entries(Object.getOwnPropertyDescriptors(constructor.prototype))) {
+    if (typeof descriptor.value !== 'function') { continue; }
+    const newDescriptor = traceCall(constructor.prototype, name, descriptor, constructor.name) ?? descriptor;
+    Object.defineProperty(constructor.prototype, name, newDescriptor);
+  }
+}

packages/aws-cdk/test/api/fake-sts.ts

@@ -125,12 +125,14 @@ export class FakeSts {
 
   private handleRequest(mockRequest: MockRequest): Record<string, any> {
     const response = (() => {
+      const identity = this.identity(mockRequest);
+
       switch (mockRequest.parsedBody.Action) {
         case 'GetCallerIdentity':
-          return this.handleGetCallerIdentity(mockRequest);
+          return this.handleGetCallerIdentity(identity);
 
         case 'AssumeRole':
-          return this.handleAssumeRole(mockRequest);
+          return this.handleAssumeRole(identity, mockRequest);
       }
 
       throw new Error(`Unrecognized Action in MockAwsHttp: ${mockRequest.parsedBody.Action}`);
@@ -139,8 +141,7 @@ export class FakeSts {
     return response;
   }
 
-  private handleGetCallerIdentity(mockRequest: MockRequest): Record<string, any> {
-    const identity = this.identity(mockRequest);
+  private handleGetCallerIdentity(identity: RegisteredIdentity): Record<string, any> {
     return {
       GetCallerIdentityResponse: {
         _attributes: { xmlns: 'https://sts.amazonaws.com/doc/2011-06-15/' },
@@ -156,15 +157,8 @@ export class FakeSts {
     };
   }
 
-  private handleAssumeRole(mockRequest: MockRequest): Record<string, any> {
-    const identity = this.identity(mockRequest);
-
-    const failureRequested = mockRequest.parsedBody.RoleArn.match(/<FAIL:([^>]+)>/);
-    if (failureRequested) {
-      const err = new Error(`STS failing by user request: ${failureRequested[1]}`);
-      (err as any).code = failureRequested[1];
-      throw err;
-    }
+  private handleAssumeRole(identity: RegisteredIdentity, mockRequest: MockRequest): Record<string, any> {
+    this.checkForFailure(mockRequest.parsedBody.RoleArn);
 
     this.assumedRoles.push({
       roleArn: mockRequest.parsedBody.RoleArn,
@@ -213,8 +207,19 @@ export class FakeSts {
     };
   }
 
+  private checkForFailure(s: string) {
+    const failureRequested = s.match(/<FAIL:([^>]+)>/);
+    if (failureRequested) {
+      const err = new Error(`STS failing by user request: ${failureRequested[1]}`);
+      (err as any).code = failureRequested[1];
+      throw err;
+    }
+  }
+
   private identity(mockRequest: MockRequest) {
     const keyId = this.accessKeyId(mockRequest);
+    this.checkForFailure(keyId);
+
     const ret = this.identities[keyId];
     if (!ret) { throw new Error(`Unrecognized access key used: ${keyId}`); }
     return ret;

packages/aws-cdk/test/api/sdk-provider.test.ts

@@ -561,6 +561,18 @@ describe('with intercepted network calls', () => {
     // THEN
     await expect(provider.defaultAccount()).resolves.toBe(undefined);
   });
+
+  test('defaultAccount returns undefined, event if STS call fails with ExpiredToken', async () => {
+    // GIVEN
+    process.env.AWS_ACCESS_KEY_ID = `${uid}'<FAIL:ExpiredToken>'`;
+    process.env.AWS_SECRET_ACCESS_KEY = 'sekrit';
+
+    // WHEN
+    const provider = await providerFromProfile(undefined);
+
+    // THEN
+    await expect(provider.defaultAccount()).resolves.toBe(undefined);
+  });
 });
 
 test('even when using a profile to assume another profile, STS calls goes through the proxy', async () => {

packages/aws-cdk/tsconfig.json

@@ -12,6 +12,7 @@
         "noUnusedParameters": true,
         "noImplicitReturns": true,
         "noFallthroughCasesInSwitch": true,
+        "experimentalDecorators": true,
         "resolveJsonModule": true,
         "composite": true,
         "incremental": true