Update scripts to read tokens more securely

.github/update-release-branch.py

@@ -16,12 +16,23 @@
 """
 
 # NB: This exact commit message is used to find commits for reverting during backports.
-# Changing it requires a transition period where both old and new versions are supported.
+# Changing it requires a transition period where both old and new versions are supported.
 BACKPORT_COMMIT_MESSAGE = 'Update version and changelog for v'
 
 # Name of the remote
 ORIGIN = 'origin'
 
+# Environment variables to check for a GitHub API token.
+TOKEN_ENVIRONMENT_VARIABLES = ('GH_TOKEN', 'GITHUB_TOKEN')
+
+# Gets a GitHub API token from one of the supported environment variables.
+def get_github_token():
+  for variable_name in TOKEN_ENVIRONMENT_VARIABLES:
+    token = os.environ.get(variable_name, '').strip()
+    if token:
+      return token
+  raise Exception('Missing GitHub token. Set GITHUB_TOKEN or GH_TOKEN.')
+
 # Runs git with the given args and returns the stdout.
 # Raises an error if git does not exit successfully (unless passed
 # allow_non_zero_exit_code=True).
@@ -270,12 +281,6 @@ def update_changelog(version):
 def main():
   parser = argparse.ArgumentParser('update-release-branch.py')
 
-  parser.add_argument(
-    '--github-token',
-    type=str,
-    required=True,
-    help='GitHub token, typically from GitHub Actions.'
-  )
   parser.add_argument(
     '--repository-nwo',
     type=str,
@@ -313,7 +318,7 @@ def main():
   target_branch = args.target_branch
   is_primary_release = args.is_primary_release
 
-  repo = Github(args.github_token).get_repo(args.repository_nwo)
+  repo = Github(get_github_token()).get_repo(args.repository_nwo)
 
   # the target branch will be of the form releases/vN, where N is the major version number
   target_branch_major_version = target_branch.strip('releases/v')

.github/workflows/update-release-branch.yml

@@ -64,11 +64,12 @@ jobs:
 
     - name: Update current release branch
       if: github.event_name == 'workflow_dispatch'
+      env:
+        GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
       run: |
         echo SOURCE_BRANCH=${REF_NAME}
         echo TARGET_BRANCH=releases/${MAJOR_VERSION}
         python .github/update-release-branch.py \
-          --github-token ${{ secrets.GITHUB_TOKEN }} \
           --repository-nwo ${{ github.repository }} \
           --source-branch '${{ env.REF_NAME }}' \
           --target-branch 'releases/${{ env.MAJOR_VERSION }}' \
@@ -107,11 +108,12 @@ jobs:
     - uses: ./.github/actions/release-initialise
 
     - name: Update older release branch
+      env:
+        GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
       run: |
         echo SOURCE_BRANCH=${SOURCE_BRANCH}
         echo TARGET_BRANCH=${TARGET_BRANCH}
         python .github/update-release-branch.py \
-          --github-token ${{ secrets.GITHUB_TOKEN }} \
           --repository-nwo ${{ github.repository }} \
           --source-branch ${SOURCE_BRANCH} \
           --target-branch ${TARGET_BRANCH} \

CONTRIBUTING.md

@@ -71,7 +71,7 @@ Once the mergeback and backport pull request have been merged, the release is co
 
 Since the `codeql-action` runs most of its testing through individual Actions workflows, there are over two hundred required jobs that need to pass in order for a PR to turn green. It would be too tedious to maintain that list manually. You can regenerate the set of required checks automatically by running the [sync-checks.ts](pr-checks/sync-checks.ts) script:
 
-- At a minimum, you must provide an argument for the `--token` input. For example, `--token "$(gh auth token)"` to use the same token that `gh` uses. If no token is provided or the token has insufficient permissions, the script will fail.
+- At a minimum, you must provide a token with permissions to update branch protection rules. For example, `gh auth token | pr-checks/sync-checks.ts --token-stdin` uses the same token that `gh` uses. You can also set the `GH_TOKEN` or `GITHUB_TOKEN` environment variable. If no token is provided or the token has insufficient permissions, the script will fail.
 - By default, the script performs a dry run and outputs information about the changes it would make to the branch protection rules. To actually apply the changes, specify the `--apply` flag.
 - If you run the script without any other arguments, it will retrieve the set of workflows that ran for the latest commit on `main`.
 - You can specify a different git ref with the `--ref` input. You will likely want to use this if you have a PR that removes or adds PR checks. For example, `--ref "some/branch/name"` to use the HEAD of the `some/branch/name` branch.

pr-checks/sync-checks.test.ts

@@ -7,7 +7,13 @@ Tests for the sync-checks.ts script
 import * as assert from "node:assert/strict";
 import { describe, it } from "node:test";
 
-import { CheckInfo, Exclusions, Options, removeExcluded } from "./sync-checks";
+import {
+  CheckInfo,
+  Exclusions,
+  Options,
+  removeExcluded,
+  resolveToken,
+} from "./sync-checks";
 
 const defaultOptions: Options = {
   apply: false,
@@ -58,3 +64,46 @@ describe("removeExcluded", async () => {
     assert.deepEqual(retained, expectedExactMatches);
   });
 });
+
+describe("resolveToken", async () => {
+  await it("reads the token from standard input", async () => {
+    const token = await resolveToken(
+      { tokenStdin: true },
+      { env: {}, readStdin: async () => " stdin-token\n" },
+    );
+    assert.equal(token, "stdin-token");
+  });
+
+  await it("reads the token from the GH_TOKEN environment variable", async () => {
+    const token = await resolveToken(
+      {},
+      { env: { GH_TOKEN: "env-token" }, readStdin: async () => "" },
+    );
+    assert.equal(token, "env-token");
+  });
+
+  await it("reads the token from the GITHUB_TOKEN environment variable", async () => {
+    const token = await resolveToken(
+      {},
+      { env: { GITHUB_TOKEN: "env-token" }, readStdin: async () => "" },
+    );
+    assert.equal(token, "env-token");
+  });
+
+  await it("rejects an empty standard input token", async () => {
+    await assert.rejects(
+      resolveToken(
+        { tokenStdin: true },
+        { env: {}, readStdin: async () => "\n" },
+      ),
+      /No token received on standard input/,
+    );
+  });
+
+  await it("rejects missing token sources", async () => {
+    await assert.rejects(
+      resolveToken({}, { env: {}, readStdin: async () => "" }),
+      /Missing authentication token/,
+    );
+  });
+});

pr-checks/sync-checks.ts

@@ -15,8 +15,8 @@ import {
 
 /** Represents the command-line options. */
 export interface Options {
-  /** The token to use to authenticate to the GitHub API. */
-  token?: string;
+  /** Whether to read the GitHub API token from standard input. */
+  tokenStdin?: boolean;
   /** The git ref to use the checks for. */
   ref?: string;
   /** Whether to actually apply the changes or not. */
@@ -31,6 +31,65 @@ const codeqlActionRepo = {
   repo: "codeql-action",
 };
 
+/** Environment variables to check for a GitHub API token. */
+const TOKEN_ENVIRONMENT_VARIABLES = ["GH_TOKEN", "GITHUB_TOKEN"];
+
+/** Represents the sources from which we can retrieve the GitHub API token. */
+interface TokenSource {
+  /** Environment variables to inspect. */
+  env: NodeJS.ProcessEnv;
+  /** Reads a token from standard input. */
+  readStdin: () => Promise<string>;
+}
+
+/** Reads the GitHub API token from standard input. */
+async function readTokenFromStdin(): Promise<string> {
+  let token = "";
+  process.stdin.setEncoding("utf8");
+  for await (const chunk of process.stdin) {
+    token += chunk;
+  }
+  return token.trim();
+}
+
+/** Gets a GitHub API token from one of the supported environment variables. */
+function getTokenFromEnvironment(env: NodeJS.ProcessEnv): string | undefined {
+  for (const variableName of TOKEN_ENVIRONMENT_VARIABLES) {
+    const token = env[variableName]?.trim();
+    if (token) {
+      return token;
+    }
+  }
+  return undefined;
+}
+
+/** Gets the token to use to authenticate to the GitHub API. */
+export async function resolveToken(
+  options: Pick<Options, "tokenStdin">,
+  tokenSource: TokenSource = {
+    env: process.env,
+    readStdin: readTokenFromStdin,
+  },
+): Promise<string> {
+  if (options.tokenStdin) {
+    const token = (await tokenSource.readStdin()).trim();
+    if (token.length === 0) {
+      throw new Error("No token received on standard input.");
+    }
+    return token;
+  }
+
+  const environmentToken = getTokenFromEnvironment(tokenSource.env);
+  if (environmentToken !== undefined) {
+    return environmentToken;
+  }
+
+  throw new Error(
+    "Missing authentication token. Set GH_TOKEN/GITHUB_TOKEN or pipe a token " +
+      "to --token-stdin.",
+  );
+}
+
 /** Represents a configuration of which checks should not be set up as required checks. */
 export interface Exclusions {
   /** A list of strings that, if contained in a check name, are excluded. */
@@ -205,9 +264,10 @@ async function updateBranch(
 async function main(): Promise<void> {
   const { values: options } = parseArgs({
     options: {
-      // The token to use to authenticate to the API.
-      token: {
-        type: "string",
+      // Read the token to use to authenticate to the API from standard input.
+      "token-stdin": {
+        type: "boolean",
+        default: false,
       },
       // The git ref for which to retrieve the check runs.
       ref: {
@@ -228,16 +288,16 @@ async function main(): Promise<void> {
     strict: true,
   });
 
-  if (options.token === undefined) {
-    throw new Error("Missing --token");
-  }
+  const token = await resolveToken({
+    tokenStdin: options["token-stdin"],
+  });
 
   console.info(
     `Oldest supported major version is: ${OLDEST_SUPPORTED_MAJOR_VERSION}`,
   );
 
   // Initialise the API client.
-  const client = getApiClient(options.token);
+  const client = getApiClient(token);
 
   // Find the check runs for the specified `ref` that we will later set as the required checks
   // for the main and release branches.