feat: ensure cred file is created with a predictable name (#130)

.github/workflows/test.yml

@@ -25,8 +25,8 @@ jobs:
       with:
         node-version: '16.x'
 
-    - name: 'npm ci'
+    - name: 'npm build'
-      run: 'npm ci'
+      run: 'npm ci && npm run build'
 
     - name: 'npm lint'
       run: 'npm run lint'
@@ -54,6 +54,9 @@ jobs:
       with:
         node-version: '16.x'
 
+    - name: 'npm build'
+      run: 'npm ci && npm run build'
+
     - id: 'auth-default'
       name: 'auth-default'
       uses: './'
@@ -119,6 +122,9 @@ jobs:
       with:
         node-version: '16.x'
 
+    - name: 'npm build'
+      run: 'npm ci && npm run build'
+
     - id: 'auth-default'
       name: 'auth-default'
       uses: './'
@@ -181,11 +187,8 @@ jobs:
       with:
         node-version: '16.x'
 
-    - name: 'npm ci'
-      run: 'npm ci'
-
     - name: 'npm build'
-      run: 'npm run build'
+      run: 'npm ci && npm run build'
 
     - name: 'auth-default'
       uses: './'

README.md

@@ -36,6 +36,15 @@ and permissions on Google Cloud.
     the checkout step or putting it after `auth` will cause future steps to be
     unable to authenticate.
 
+-   If you plan to create binaries, containers, pull requests, or other
+    releases, add the following to your `.gitignore` to prevent accidentially
+    committing credentials to your release artifact:
+
+    ```text
+    # Ignore generated credentials from google-github-actions/auth
+    gha-creds-*.json
+    ```
+
 
 ## Usage
 

docs/TROUBLESHOOTING.md

@@ -1,8 +1,10 @@
 # Troubleshooting
 
--   When troubleshooting "permission denied" errors from `auth` for Workload
+## Permission denied
-    Identity, the first step is to ask the `auth` plugin to generate an OAuth
+
-    access token. Do this by adding `token_format: 'access_token'` to your YAML:
+When troubleshooting "permission denied" errors from `auth` for Workload
+Identity, the first step is to ask the `auth` plugin to generate an OAuth access
+token. Do this by adding `token_format: 'access_token'` to your YAML:
 
 ```yaml
 - uses: 'google-github-actions/auth@v0'
@@ -11,33 +13,33 @@
     token_format: 'access_token'
 ```
 
-    If your workflow _succeeds_ after adding the step to generate an access
+If your workflow _succeeds_ after adding the step to generate an access token,
-    token, it means Workload Identity Federation is configured correctly and the
+it means Workload Identity Federation is configured correctly and the issue is
-    issue is in subsequent actions. You can remove the `token_format` from your
+in subsequent actions. You can remove the `token_format` from your YAML. To
-    YAML. To further debug:
+further debug:
 
-    1.  Look at the [debug logs][debug-logs] to see exactly which step is
+1.  Look at the [debug logs][debug-logs] to see exactly which step is failing.
-        failing. Ensure you are using the latest version of that GitHub Action.
+    Ensure you are using the latest version of that GitHub Action.
 
-    1.  Make sure you use `actions/checkout@v2` **before** the `auth` action in
+1.  Make sure you use `actions/checkout@v2` **before** the `auth` action in your
-        your workflow.
+    workflow.
 
-    1.  If the failing action is from `google-github-action/*`, please file an
+1.  If the failing action is from `google-github-action/*`, please file an issue
-        issue in the corresponding repository.
+    in the corresponding repository.
 
 1.  If the failing action is from an external action, please file an issue
     against that repository. The `auth` action exports Google Application
     Default Credentials (ADC). Ask the action author to ensure they are
-        processing ADC correctly and using the latest versions of the Google
+    processing ADC correctly and using the latest versions of the Google client
-        client libraries. Please note that we do not have control over actions
+    libraries. Please note that we do not have control over actions outside of
-        outside of `google-github-actions`.
+    `google-github-actions`.
 
-    If your workflow _fails_ after adding the the step to generate an access
+If your workflow _fails_ after adding the the step to generate an access token,
-    token, it likely means there is a misconfiguration with Workload Identity.
+it likely means there is a misconfiguration with Workload Identity. Here are
-    Here are some common sources of errors:
+some common sources of errors:
 
-    1.  Look at the [debug logs][debug-logs] to see exactly which step is
+1.  Look at the [debug logs][debug-logs] to see exactly which step is failing.
-        failing. Ensure you are using the latest version of that GitHub Action.
+    Ensure you are using the latest version of that GitHub Action.
 
 1.  Ensure the value for `workload_identity_provider` is the full _Provider_
     name, **not** the _Pool_ name:
@@ -49,35 +51,54 @@
 
 1.  Ensure you have created an **Attribute Mapping** for any **Attribute
     Conditions** or **Service Account Impersonation** principals. You cannot
-        create an Attribute Condition unless you map that value from the
+    create an Attribute Condition unless you map that value from the incoming
-        incoming GitHub OIDC token. You cannot grant permissions to impersonate
+    GitHub OIDC token. You cannot grant permissions to impersonate a Service
-        a Service Account on an attribute unless you map that value from the
+    Account on an attribute unless you map that value from the incoming GitHub
-        incoming GitHub OIDC token.
+    OIDC token.
 
 1.  Ensure you have waited at least 5 minutes between making changes to the
     Workload Identity Pool and Workload Identity Provider. Changes to these
     resources are eventually consistent.
 
--   "The size of mapped attribute exceeds the 127 bytes limit." This error
+
-    indicates that the GitHub OIDC token had a claim that exceeded the maximum
+## Subject exceeds the 127 byte limit
-    allowed value of 127 bytes. In general, 1 byte = 1 character. This most
+
-    common reason this occurs is due to long repo names or long branch names.
+If you get an error like:
+
+```text
+The size of mapped attribute exceeds the 127 bytes limit.
+```
+
+it means  that the GitHub OIDC token had a claim that exceeded the maximum
+allowed value of 127 bytes. In general, 1 byte = 1 character. This most common
+reason this occurs is due to long repo names or long branch names.
 
 **This is a limit imposed by Google Cloud IAM.** We have no control over
 this value. It is documented [here][wif-byte-limit]. Please [file feedback
 with the Google Cloud IAM team][iam-feedback]. The only mitigation is to use
 shorter repo names or shorter branch names.
 
--   The credentials file was bundled into my binary, container, or pull request!
-    By default, the `auth` action exports credentials to the current workspace
-    so that the credentials are automatically available to future steps and
-    Docker-based actions. The credentials file is automatically removed when the
-    job finishes.
 
-    This means, after `auth` completes, the workspace is dirty and contains a
+## Dirty git or bundled credentials
+
+By default, the `auth` action exports credentials to the current workspace so
+that the credentials are automatically available to future steps and
+Docker-based actions. The credentials file is automatically removed when the job
+finishes.
+
+This means, after the `auth` action runs, the workspace is dirty and contains a
 credentials file. This means creating a pull request, compiling a binary, or
-    building a Docker container, will include said credential file. There are a
+building a Docker container, will include said credential file. There are a few
-    few ways to fix this issue:
+ways to fix this issue:
+
+-   Add and commit the following lines to your `.gitignore`:
+
+    ```text
+    # Ignore generated credentials from google-github-actions/auth
+    gha-creds-*.json
+    ```
+
+    **This requires the `auth` action be v0.6.0 or later.**
 
 -   Re-order your steps. In most cases, you can re-order your steps such
     that `auth` comes _after_ the "compilation" step:

src/client/credentials_json_client.ts

@@ -4,7 +4,6 @@ import { createSign } from 'crypto';
 import {
   isServiceAccountKey,
   parseCredential,
-  randomFilepath,
   ServiceAccountKey,
   toBase64,
   writeSecureFile,
@@ -124,8 +123,7 @@ export class CredentialsJSONClient implements AuthClient {
    * createCredentialsFile creates a Google Cloud credentials file that can be
    * set as GOOGLE_APPLICATION_CREDENTIALS for gcloud and client libraries.
    */
-  async createCredentialsFile(outputDir: string): Promise<string> {
+  async createCredentialsFile(outputPath: string): Promise<string> {
-    const outputFile = randomFilepath(outputDir);
+    return await writeSecureFile(outputPath, JSON.stringify(this.#credentials));
-    return await writeSecureFile(outputFile, JSON.stringify(this.#credentials));
   }
 }

src/client/workload_identity_client.ts

@@ -1,7 +1,7 @@
 'use strict';
 
 import { URL } from 'url';
-import { randomFilepath, writeSecureFile } from '@google-github-actions/actions-utils';
+import { writeSecureFile } from '@google-github-actions/actions-utils';
 
 import { AuthClient } from './auth_client';
 import { BaseClient } from '../base';
@@ -182,7 +182,7 @@ export class WorkloadIdentityClient implements AuthClient {
    * createCredentialsFile creates a Google Cloud credentials file that can be
    * set as GOOGLE_APPLICATION_CREDENTIALS for gcloud and client libraries.
    */
-  async createCredentialsFile(outputDir: string): Promise<string> {
+  async createCredentialsFile(outputPath: string): Promise<string> {
     const requestURL = new URL(this.#oidcTokenRequestURL);
 
     // Append the audience value to the request.
@@ -209,7 +209,6 @@ export class WorkloadIdentityClient implements AuthClient {
       },
     };
 
-    const outputFile = randomFilepath(outputDir);
+    return await writeSecureFile(outputPath, JSON.stringify(data));
-    return await writeSecureFile(outputFile, JSON.stringify(data));
   }
 }

src/main.ts

@@ -1,5 +1,7 @@
 'use strict';
 
+import { join as pathjoin } from 'path';
+
 import {
   debug as logDebug,
   exportVariable,
@@ -26,7 +28,7 @@ import { WorkloadIdentityClient } from './client/workload_identity_client';
 import { CredentialsJSONClient } from './client/credentials_json_client';
 import { AuthClient } from './client/auth_client';
 import { BaseClient } from './base';
-import { buildDomainWideDelegationJWT } from './utils';
+import { buildDomainWideDelegationJWT, generateCredentialsFilename } from './utils';
 
 const secretsWarning =
   `If you are specifying input values via GitHub secrets, ensure the secret ` +
@@ -153,7 +155,9 @@ async function run(): Promise<void> {
       }
 
       // Create credentials file.
-      const credentialsPath = await client.createCredentialsFile(githubWorkspace);
+      const outputFile = generateCredentialsFilename();
+      const outputPath = pathjoin(githubWorkspace, outputFile);
+      const credentialsPath = await client.createCredentialsFile(outputPath);
       logInfo(`Created credentials file at "${credentialsPath}"`);
 
       // Output to be available to future steps.

src/utils.ts

@@ -1,5 +1,7 @@
 'use strict';
 
+import { randomFilename } from '@google-github-actions/actions-utils';
+
 /**
  * buildDomainWideDelegationJWT constructs an _unsigned_ JWT to be used for a
  * DWD exchange. The JWT must be signed and then exchanged with the OAuth
@@ -35,3 +37,19 @@ export function buildDomainWideDelegationJWT(
 
   return JSON.stringify(body);
 }
+
+/**
+ * generateCredentialsFilename creates a predictable filename under which
+ * credentials are written. This string is the filename, not the filepath. It must match the format:
+ *
+ *     gha-creds-[a-z0-9]{16}.json
+ *
+ * For example:
+ *
+ *     gha-creds-ef801c3bb35b52e5.json
+ *
+ * @return Filename
+ */
+export function generateCredentialsFilename(): string {
+  return 'gha-creds-' + randomFilename(8) + '.json';
+}

tests/client/credentials_json_client.test.ts

@@ -3,9 +3,12 @@
 import 'mocha';
 import { expect } from 'chai';
 
+import { join as pathjoin } from 'path';
 import { readFileSync } from 'fs';
 import { tmpdir } from 'os';
 
+import { randomFilename } from '@google-github-actions/actions-utils';
+
 import { CredentialsJSONClient } from '../../src/client/credentials_json_client';
 
 // Yes, this is a real private key. No, it's not valid for authenticating
@@ -104,14 +107,14 @@ describe('CredentialsJSONClient', () => {
 
   describe('#createCredentialsFile', () => {
     it('writes the file', async () => {
-      const tmp = tmpdir();
+      const outputFile = pathjoin(tmpdir(), randomFilename());
       const client = new CredentialsJSONClient({
         credentialsJSON: credentialsJSON,
       });
 
       const exp = JSON.parse(credentialsJSON);
 
-      const pth = await client.createCredentialsFile(tmp);
+      const pth = await client.createCredentialsFile(outputFile);
       const data = readFileSync(pth);
       const got = JSON.parse(data.toString('utf8'));
 

tests/client/workload_identity_client.test.ts

@@ -4,7 +4,11 @@ import 'mocha';
 import { expect } from 'chai';
 
 import { tmpdir } from 'os';
+import { join as pathjoin } from 'path';
 import { readFileSync } from 'fs';
+
+import { randomFilename } from '@google-github-actions/actions-utils';
+
 import { WorkloadIdentityClient } from '../../src/client/workload_identity_client';
 
 describe('WorkloadIdentityClient', () => {
@@ -71,7 +75,7 @@ describe('WorkloadIdentityClient', () => {
 
   describe('#createCredentialsFile', () => {
     it('writes the file', async () => {
-      const tmp = tmpdir();
+      const outputFile = pathjoin(tmpdir(), randomFilename());
       const client = new WorkloadIdentityClient({
         projectID: 'my-project',
         providerID: 'my-provider',
@@ -101,7 +105,7 @@ describe('WorkloadIdentityClient', () => {
         type: 'external_account',
       };
 
-      const pth = await client.createCredentialsFile(tmp);
+      const pth = await client.createCredentialsFile(outputFile);
       const data = readFileSync(pth);
       const got = JSON.parse(data.toString('utf8'));
 

tests/utils.test.ts

@@ -3,7 +3,7 @@
 import 'mocha';
 import { expect } from 'chai';
 
-import { buildDomainWideDelegationJWT } from '../src/utils';
+import { buildDomainWideDelegationJWT, generateCredentialsFilename } from '../src/utils';
 
 describe('Utils', () => {
   describe('#buildDomainWideDelegationJWT', () => {
@@ -54,4 +54,13 @@ describe('Utils', () => {
       });
     });
   });
+
+  describe('#generateCredentialsFilename', () => {
+    it('returns a string matching the regex', () => {
+      for (let i = 0; i < 10; i++) {
+        const filename = generateCredentialsFilename();
+        expect(filename).to.match(/gha-creds-[0-9a-z]{16}\.json/);
+      }
+    });
+  });
 });