gitlab-mr-ai

AI-powered CLI tool to generate GitLab Merge Request summaries using Google Gemini.

Generate clear, structured summaries for your GitLab merge requests — fully automated and CI/CD-friendly. This CLI tool analyzes diffs from your MR and uses Gemini to generate a concise description and key file changes.

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📚 Table of Contents

• gitlab-mr-ai
  • 📚 Table of Contents
  • 🚀 Installation
  • 💻 Usage (Local)
  • ⚙️ Usage (GitLab CI/CD)
  • 🧩 CLI Parameters
    • Flag Descriptions
  • 🧠 Branch & Ticket Detection
  • 🌍 General Usage & Fallbacks
  • 🔐 Environment Variables
  • 🧼 Troubleshooting
  • 📦 License

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🚀 Installation

npm install -g gitlab-mr-ai
# or use npx without install
npx gitlab-mr-ai generate --mr 123

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💻 Usage (Local)

mr-ai generate --mr <merge-request-id> [options]

Example:

mr-ai generate --mr 927 --output console

To load environment variables locally, you can:

# using dotenv-cli (recommended for simplicity)
npm install -g dotenv-cli
dotenv -e .env -- mr-ai generate --mr 927

# or with native bash
source .env && mr-ai generate --mr 927

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⚙️ Usage (GitLab CI/CD)

💡 You can configure GitLab CI/CD to run this tool automatically or manually on merge requests.

Example .gitlab-ci.yml job:

mr-summary:
  stage: quality-gate
  image: node:20
  script:
    - npx gitlab-mr-ai generate --mr "$CI_MERGE_REQUEST_IID" --output post
  rules:
    - if: $CI_PIPELINE_SOURCE == "merge_request_event"
      when: manual

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🧩 CLI Parameters

Below is a list of CLI flags supported by mr-ai, including what they do and when to use them.

Flag	Alias	Required	Description
--mr	-m	✅ Yes	Merge request IID to summarize
--template	-t	❌ No	Template name (standard, bug-fix, general) or file path to .md
--prompt	-p	❌ No	Custom prompt file path (.txt) for Gemini
--output	-o	❌ No	console, file, or post (default: console)

Flag Descriptions

• --mr, -m (required)
  The Merge Request IID (internal ID visible in the GitLab URL, like /merge_requests/123). This is used to fetch the diff and identify which MR to summarize.

• --template, -t
  Optional. Specifies which Markdown template to use. You can:

  • Pass a built-in template name: standard, bug-fix, or general
  • Or pass a file path to a custom template, e.g. ./my-template.md

• --prompt, -p
  Optional. Specify a custom prompt file (.txt) to send to Gemini. If not provided, a default prompt will be used.

• --output, -o
  Optional. Defines where the generated summary goes:

  • console (default): print to terminal
  • file: write to mr-summary-<mrId>.md
  • post: update the MR's description directly in GitLab

# Basic usage (console output)
mr-ai generate --mr 1010

# Use general template explicitly
mr-ai generate --mr 1010 --template general

# Use external template & prompt, write to file
mr-ai generate --mr 1010 --template ./my-template.md --prompt ./my-prompt.txt --output file

# Post directly to GitLab MR
mr-ai generate --mr 1010 --output post

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🧠 Branch & Ticket Detection

If no --template is provided, the CLI tries to auto-detect based on your branch name:

• fix/123-title → uses bug-fix.md
• feat/PL-456-feature → uses standard.md
• Otherwise → fallback to general.md

Ticket ID is also auto-detected and injected into the template:

• #123 for numeric branches
• PL-456 if prefixed

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🌍 General Usage & Fallbacks

You do not need to follow any branch naming convention.

To disable smart detection and use the general fallback always:

mr-ai generate --mr 9001 --template general

Alternatively, if you prefer to keep smart detection off by default, you can:

• Use a generic or unmatched branch name (e.g. feature/login-screen)
• Pass the --template general flag explicitly in every usage (recommended for general use cases)

Fallbacks will:

• Use the general.md template if format isn't recognized
• Skip ticket injection if none detected
• Still render valid output from Gemini

You can also:

• Provide your own Markdown template (--template ./custom.md)
• Provide your own prompt (--prompt ./custom.txt)

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🔐 Environment Variables

❗ When running in GitLab CI/CD, these variables should be configured under Settings → CI/CD → Variables. You do not need to manually export them in the pipeline script.

Set via .env or CI variables:

Key	Required	Description
GEMINI_API_KEY	✅	Google Generative AI API key
GITLAB_TOKEN	✅	GitLab personal access token (project read/write)
GITLAB_PROJECT_ID	✅	GitLab project numeric ID
GITLAB_API_URL	❌	GitLab API URL (default: https://gitlab.com/api/v4)
GEMINI_MODEL	❌	Gemini model ID (default: gemini-1.5-flash)

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🧼 Troubleshooting

Missing required env variable:

❌ Missing required .env variables: GEMINI_API_KEY, GITLAB_TOKEN

➡️ Check your .env or CI settings

Template not found:

❌ Failed to read template at ./custom.md

➡️ Make sure the file path exists and is valid

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📦 License

MIT