Add support for reference repository parameter

src/git-command-manager.ts

@@ -43,6 +43,7 @@ export interface IGitCommandManager {
   lfsInstall(): Promise<void>
   log1(format?: string): Promise<string>
   remoteAdd(remoteName: string, remoteUrl: string): Promise<void>
+  referenceAdd(reference: string): Promise<void>
   removeEnvironmentVariable(name: string): void
   revParse(ref: string): Promise<string>
   setEnvironmentVariable(name: string, value: string): void
@@ -343,6 +344,15 @@ class GitCommandManager {
     await this.execGit(['remote', 'add', remoteName, remoteUrl])
   }
 
+  async referenceAdd(alternateObjects: string): Promise<void> {
+    const alternatePath = path.join(
+      this.workingDirectory,
+      '.git/objects/info/alternates'
+    )
+    core.info(`Adding a git alternate to reference repo at ${alternateObjects}`)
+    await fs.promises.writeFile(alternatePath, `${alternateObjects}\n`)
+  }
+
   removeEnvironmentVariable(name: string): void {
     delete this.gitEnv[name]
   }

src/git-source-provider.ts

@@ -110,6 +110,18 @@ export async function getSource(settings: IGitSourceSettings): Promise<void> {
       await git.init()
       await git.remoteAdd('origin', repositoryUrl)
       core.endGroup()
+
+      if (settings.reference !== undefined) {
+        const alternateObjects = path.join(settings.reference, '/objects')
+
+        if (fsHelper.directoryExistsSync(alternateObjects, false)) {
+          core.startGroup('Adding a reference repository')
+          await git.referenceAdd(alternateObjects)
+          core.endGroup()
+        } else {
+          core.warning(`Reference repository was specified, but directory ${alternateObjects} does not exists`);
+        }
+      }
     }
 
     // Disable automatic garbage collection

src/git-source-settings.ts

@@ -44,6 +44,11 @@ export interface IGitSourceSettings {
    */
   fetchDepth: number
 
+  /**
+   * The local reference repository
+   */
+  reference: string | undefined
+
   /**
    * Indicates whether to fetch LFS objects
    */

src/input-helper.ts

@@ -141,5 +141,8 @@ export async function getInputs(): Promise<IGitSourceSettings> {
   result.githubServerUrl = core.getInput('github-server-url')
   core.debug(`GitHub Host URL = ${result.githubServerUrl}`)
 
+  result.reference = core.getInput('reference')
+  core.debug(`Reference repository = ${result.reference}`)
+
   return result
 }