Persist creds to a separate file

src/git-auth-helper.ts

@@ -43,6 +43,8 @@ class GitAuthHelper {
   private sshKeyPath = ''
   private sshKnownHostsPath = ''
   private temporaryHomePath = ''
+  private credentialsConfigPath = '' // Path to separate credentials config file in RUNNER_TEMP
+  private credentialsIncludeKeys: string[] = [] // Track includeIf/include config keys for cleanup
 
   constructor(
     gitCommandManager: IGitCommandManager,
@@ -81,6 +83,22 @@ class GitAuthHelper {
     await this.configureToken()
   }
 
+  private async getCredentialsConfigPath(): Promise<string> {
+    if (this.credentialsConfigPath) {
+      return this.credentialsConfigPath
+    }
+
+    const runnerTemp = process.env['RUNNER_TEMP'] || ''
+    assert.ok(runnerTemp, 'RUNNER_TEMP is not defined')
+
+    // Create a unique filename for this checkout instance
+    const configFileName = `git-credentials-${uuid()}.config`
+    this.credentialsConfigPath = path.join(runnerTemp, configFileName)
+
+    core.debug(`Credentials config path: ${this.credentialsConfigPath}`)
+    return this.credentialsConfigPath
+  }
+
   async configureTempGlobalConfig(): Promise<string> {
     // Already setup global config
     if (this.temporaryHomePath?.length > 0) {
@@ -126,10 +144,10 @@ class GitAuthHelper {
 
   async configureGlobalAuth(): Promise<void> {
     // 'configureTempGlobalConfig' noops if already set, just returns the path
-    const newGitConfigPath = await this.configureTempGlobalConfig()
+    await this.configureTempGlobalConfig()
     try {
       // Configure the token
-      await this.configureToken(newGitConfigPath, true)
+      await this.configureToken(true)
 
       // Configure HTTPS instead of SSH
       await this.git.tryConfigUnset(this.insteadOfKey, true)
@@ -272,32 +290,62 @@ class GitAuthHelper {
     }
   }
 
-  private async configureToken(
-    configPath?: string,
-    globalConfig?: boolean
-  ): Promise<void> {
-    // Validate args
-    assert.ok(
-      (configPath && globalConfig) || (!configPath && !globalConfig),
-      'Unexpected configureToken parameter combinations'
-    )
+  private async configureToken(globalConfig?: boolean): Promise<void> {
+    // Get the credentials config file path in RUNNER_TEMP
+    const credentialsConfigPath = await this.getCredentialsConfigPath()
 
-    // Default config path
-    if (!configPath && !globalConfig) {
-      configPath = path.join(this.git.getWorkingDirectory(), '.git', 'config')
-    }
-
-    // Configure a placeholder value. This approach avoids the credential being captured
-    // by process creation audit events, which are commonly logged. For more information,
-    // refer to https://docs.microsoft.com/en-us/windows-server/identity/ad-ds/manage/component-updates/command-line-process-auditing
+    // Write placeholder to the separate credentials config file using git config.
+    // This approach avoids the credential being captured by process creation audit events,
+    // which are commonly logged. For more information, refer to
+    // https://docs.microsoft.com/en-us/windows-server/identity/ad-ds/manage/component-updates/command-line-process-auditing
     await this.git.config(
       this.tokenConfigKey,
       this.tokenPlaceholderConfigValue,
-      globalConfig
+      false,
+      false,
+      credentialsConfigPath
     )
 
-    // Replace the placeholder
-    await this.replaceTokenPlaceholder(configPath || '')
+    // Replace the placeholder in the credentials config file
+    await this.replaceTokenPlaceholder(credentialsConfigPath)
+
+    // Add include or includeIf to reference the credentials config
+    if (globalConfig) {
+      // For global config, use unconditional include.
+      // No need to track for cleanup since the temp .gitconfig file (which contains
+      // this include.path entry) gets deleted by removeGlobalConfig().
+      await this.git.config('include.path', credentialsConfigPath, true)
+    } else {
+      // For local config, use includeIf.gitdir to match the .git directory.
+      // Configure for both host and container paths to support Docker container actions.
+      const gitDir = path.join(this.git.getWorkingDirectory(), '.git')
+      const hostIncludeKey = `includeIf.gitdir:${gitDir}.path`
+      await this.git.config(hostIncludeKey, credentialsConfigPath)
+      this.credentialsIncludeKeys.push(hostIncludeKey)
+
+      // Configure for container scenario where paths are mapped to fixed locations
+      const githubWorkspace = process.env['GITHUB_WORKSPACE']
+      if (githubWorkspace) {
+        // Calculate the relative path of the working directory from GITHUB_WORKSPACE
+        const workingDirectory = this.git.getWorkingDirectory()
+        const relativePath = path.relative(githubWorkspace, workingDirectory)
+
+        // Container paths: GITHUB_WORKSPACE -> /github/workspace, RUNNER_TEMP -> /github/runner_temp
+        const containerGitDir = path.posix.join(
+          '/github/workspace',
+          relativePath,
+          '.git'
+        )
+        const containerCredentialsPath = path.posix.join(
+          '/github/runner_temp',
+          path.basename(credentialsConfigPath)
+        )
+
+        const containerIncludeKey = `includeIf.gitdir:${containerGitDir}.path`
+        await this.git.config(containerIncludeKey, containerCredentialsPath)
+        this.credentialsIncludeKeys.push(containerIncludeKey)
+      }
+    }
   }
 
   private async replaceTokenPlaceholder(configPath: string): Promise<void> {
@@ -348,6 +396,24 @@ class GitAuthHelper {
   private async removeToken(): Promise<void> {
     // HTTP extra header
     await this.removeGitConfig(this.tokenConfigKey)
+
+    // Remove include/includeIf config entries
+    for (const includeKey of this.credentialsIncludeKeys) {
+      await this.removeGitConfig(includeKey)
+    }
+    this.credentialsIncludeKeys = []
+
+    // Remove credentials config file
+    if (this.credentialsConfigPath) {
+      try {
+        await io.rmRF(this.credentialsConfigPath)
+      } catch (err) {
+        core.debug(`${(err as any)?.message ?? err}`)
+        core.warning(
+          `Failed to remove credentials config '${this.credentialsConfigPath}'`
+        )
+      }
+    }
   }
 
   private async removeGitConfig(

src/git-command-manager.ts

@@ -28,7 +28,8 @@ export interface IGitCommandManager {
     configKey: string,
     configValue: string,
     globalConfig?: boolean,
-    add?: boolean
+    add?: boolean,
+    configFile?: string
   ): Promise<void>
   configExists(configKey: string, globalConfig?: boolean): Promise<boolean>
   fetch(
@@ -223,9 +224,15 @@ class GitCommandManager {
     configKey: string,
     configValue: string,
     globalConfig?: boolean,
-    add?: boolean
+    add?: boolean,
+    configFile?: string
   ): Promise<void> {
-    const args: string[] = ['config', globalConfig ? '--global' : '--local']
+    const args: string[] = ['config']
+    if (configFile) {
+      args.push('--file', configFile)
+    } else {
+      args.push(globalConfig ? '--global' : '--local')
+    }
     if (add) {
       args.push('--add')
     }