Default branch checkout option

README.md

@@ -29,6 +29,11 @@ Please refer to the [release page](https://github.com/actions/checkout/releases/
     # Otherwise, uses the default branch.
     ref: ''
 
+    # Indicates whether to checkout the default repository branch if the requested ref
+    # does not exist
+    # Default: false
+    default-branch-checkout: ''
+
     # Personal access token (PAT) used to fetch the repository. The PAT is configured
     # with the local git config, which enables your scripts to run authenticated git
     # commands. The post-job step removes the PAT.

__test__/git-auth-helper.test.ts

@@ -813,6 +813,7 @@ async function setup(testName: string): Promise<void> {
     nestedSubmodules: false,
     persistCredentials: true,
     ref: 'refs/heads/main',
+    defaultBranchCheckout: false,
     repositoryName: 'my-repo',
     repositoryOwner: 'my-org',
     repositoryPath: '',

__test__/input-helper.test.ts

@@ -80,6 +80,7 @@ describe('input-helper tests', () => {
     expect(settings.commit).toBeTruthy()
     expect(settings.commit).toBe('1234567890123456789012345678901234567890')
     expect(settings.filter).toBe(undefined)
+    expect(settings.defaultBranchCheckout).toBe(false)
     expect(settings.sparseCheckout).toBe(undefined)
     expect(settings.sparseCheckoutConeMode).toBe(true)
     expect(settings.fetchDepth).toBe(1)

action.yml

@@ -9,6 +9,9 @@ inputs:
       The branch, tag or SHA to checkout. When checking out the repository that
       triggered a workflow, this defaults to the reference or SHA for that
       event.  Otherwise, uses the default branch.
+  default-branch-checkout:
+    description: 'Indicates whether to checkout the default repository branch if the requested ref does not exist'
+    default: false
   token:
     description: >
       Personal access token (PAT) used to fetch the repository. The PAT is configured

dist/index.js

@@ -1250,7 +1250,7 @@ function getSource(settings) {
             else if (settings.sparseCheckout) {
                 fetchOptions.filter = 'blob:none';
             }
-            if (settings.fetchDepth <= 0) {
+            if (settings.fetchDepth <= 0 || settings.defaultBranchCheckout) {
                 // Fetch all branches and tags
                 let refSpec = refHelper.getRefSpecForAllHistory(settings.ref, settings.commit);
                 yield git.fetch(refSpec, fetchOptions);
@@ -1270,7 +1270,22 @@ function getSource(settings) {
             core.endGroup();
             // Checkout info
             core.startGroup('Determining the checkout info');
-            const checkoutInfo = yield refHelper.getCheckoutInfo(git, settings.ref, settings.commit);
+            let checkoutInfo;
+            try {
+                checkoutInfo = yield refHelper.getCheckoutInfo(git, settings.ref, settings.commit);
+            }
+            catch (error) {
+                if (settings.defaultBranchCheckout) {
+                    core.info('Could not determine the checkout info. Trying the default repository branch');
+                    const repositoryDefaultBranch = settings.sshKey
+                        ? yield git.getDefaultBranch(repositoryUrl)
+                        : yield githubApiHelper.getDefaultBranch(settings.authToken, settings.repositoryOwner, settings.repositoryName);
+                    checkoutInfo = yield refHelper.getCheckoutInfo(git, repositoryDefaultBranch, settings.commit);
+                }
+                else {
+                    throw error;
+                }
+            }
             core.endGroup();
             // LFS fetch
             // Explicit lfs-fetch to avoid slow checkout (fetches one lfs object at a time).
@@ -1724,6 +1739,11 @@ function getInputs() {
         }
         core.debug(`ref = '${result.ref}'`);
         core.debug(`commit = '${result.commit}'`);
+        // Default branch checkout
+        result.defaultBranchCheckout =
+            (core.getInput('default-branch-checkout') || 'false').toUpperCase() ===
+                'TRUE';
+        core.debug(`default-branch-checkout = '${result.defaultBranchCheckout}'`);
         // Clean
         result.clean = (core.getInput('clean') || 'true').toUpperCase() === 'TRUE';
         core.debug(`clean = ${result.clean}`);

src/git-source-provider.ts

@@ -166,7 +166,7 @@ export async function getSource(settings: IGitSourceSettings): Promise<void> {
       fetchOptions.filter = 'blob:none'
     }
 
-    if (settings.fetchDepth <= 0) {
+    if (settings.fetchDepth <= 0 || settings.defaultBranchCheckout) {
       // Fetch all branches and tags
       let refSpec = refHelper.getRefSpecForAllHistory(
         settings.ref,
@@ -190,11 +190,34 @@ export async function getSource(settings: IGitSourceSettings): Promise<void> {
 
     // Checkout info
     core.startGroup('Determining the checkout info')
-    const checkoutInfo = await refHelper.getCheckoutInfo(
-      git,
-      settings.ref,
-      settings.commit
-    )
+    let checkoutInfo: refHelper.ICheckoutInfo
+    try {
+      checkoutInfo = await refHelper.getCheckoutInfo(
+        git,
+        settings.ref,
+        settings.commit
+      )
+    } catch (error) {
+      if (settings.defaultBranchCheckout) {
+        core.info(
+          'Could not determine the checkout info. Trying the default repository branch'
+        )
+        const repositoryDefaultBranch = settings.sshKey
+          ? await git.getDefaultBranch(repositoryUrl)
+          : await githubApiHelper.getDefaultBranch(
+              settings.authToken,
+              settings.repositoryOwner,
+              settings.repositoryName
+            )
+        checkoutInfo = await refHelper.getCheckoutInfo(
+          git,
+          repositoryDefaultBranch,
+          settings.commit
+        )
+      } else {
+        throw error
+      }
+    }
     core.endGroup()
 
     // LFS fetch

src/git-source-settings.ts

@@ -19,6 +19,11 @@ export interface IGitSourceSettings {
    */
   ref: string
 
+  /**
+   * Indicates whether to checkout the default repository branch if the requested ref does not exist
+   */
+  defaultBranchCheckout: boolean
+
   /**
    * The commit to checkout
    */

src/input-helper.ts

@@ -78,6 +78,12 @@ export async function getInputs(): Promise<IGitSourceSettings> {
   core.debug(`ref = '${result.ref}'`)
   core.debug(`commit = '${result.commit}'`)
 
+  // Default branch checkout
+  result.defaultBranchCheckout =
+    (core.getInput('default-branch-checkout') || 'false').toUpperCase() ===
+    'TRUE'
+  core.debug(`default-branch-checkout = '${result.defaultBranchCheckout}'`)
+
   // Clean
   result.clean = (core.getInput('clean') || 'true').toUpperCase() === 'TRUE'
   core.debug(`clean = ${result.clean}`)