feat: add support for headless OAuth authentication via credentials file

[jpoehnelt]

This bypasses some of the challenges in #187 and #63 by allowing the developer to provide credentials directly.

Tested with:

GEMINI_CLI_WORKSPACE_OAUTH_CREDENTIALS=~/.config/gcloud/application_default_credentials.json gemini

[gemini-code-assist]

Summary of Changes

Hello @jpoehnelt, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request significantly enhances the flexibility of the gemini CLI by introducing a headless OAuth authentication mechanism. This allows users to authenticate and utilize the CLI in non-interactive environments like Docker containers, SSH sessions, or continuous integration systems, by providing credentials through a specified JSON file. This change streamlines automation and broadens the utility of the tool in various deployment scenarios.

Highlights

• Headless OAuth Authentication: Introduced support for headless OAuth authentication, enabling the use of the CLI in environments without a browser, such as Docker, SSH, or CI/CD pipelines.
• Credentials File Support: Implemented the ability to provide OAuth credentials via a JSON file, specified by the GEMINI_CLI_WORKSPACE_OAUTH_CREDENTIALS environment variable.
• Multiple Credential Formats: Added support for two credential file formats: the gcloud Application Default Credentials (ADC) format (type: "authorized_user") and raw Google Auth.Credentials JSON.
• Documentation Update: Updated the README.md with detailed instructions on how to set up and use headless authentication, including steps for creating an OAuth Client ID, enabling required APIs, generating credentials with gcloud, and using them.

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Changelog

• README.md
  • Added a new section "Headless / Docker Authentication" with detailed steps.
  • Included instructions for creating an OAuth Client ID in Google Cloud Console.
  • Listed required Google APIs to enable.
  • Provided a gcloud command example for generating credentials with specific scopes.
  • Explained how to use the generated credentials via an environment variable.
  • Added a note about supporting both gcloud ADC and raw OAuth token JSON formats.
• workspace-server/src/auth/AuthManager.ts
  • Imported the fs module for file system operations.
  • Added a new authentication path that checks for the GEMINI_CLI_WORKSPACE_OAUTH_CREDENTIALS environment variable.
  • Implemented logic to read and parse the JSON credentials file.
  • Added conditional handling to differentiate between gcloud ADC format (authorized_user) and raw Auth.Credentials JSON.
  • Created and configured Auth.OAuth2Client instances based on the detected credential format.

Activity

• No human activity has been recorded for this pull request.

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[gemini-code-assist]

Code Review

This pull request adds a valuable feature for headless authentication using a credentials file, which is great for CI/CD and other non-interactive environments. The implementation is mostly solid, but I have a couple of suggestions to improve robustness and performance in AuthManager.ts. Specifically, I recommend switching to asynchronous file reading to avoid blocking the event loop and adding validation for the credential file contents to handle potential malformed JSON gracefully.

[jpoehnelt]

/gemini review

[gemini-code-assist]

Code Review

This pull request introduces a valuable feature for headless authentication using a credentials file. The implementation is generally well-done, and the documentation is thorough. I've provided a few suggestions to enhance the robustness and maintainability of the authentication logic. Additionally, I've highlighted a potential security concern in the README regarding an overly permissive OAuth scope that should be reviewed.