In the fast-paced world of software development, codebases grow exponentially. For organizations managing hundreds of repositories and microservices, finding a specific function definition, a usage pattern, or a variable declaration can feel like searching for a needle in a haystack.

OpenGrok has long been the gold standard for high-performance code search, offering powerful indexing and cross-referencing capabilities. However, maintaining a fresh index in a dynamic environment—where new repositories are created and code is pushed constantly—remains a significant operational hurdle.

Introducing Mimir, a robust, Docker-based solution designed to automate the orchestration of OpenGrok, ensuring your code search engine is always in sync with your source control.

What is Mimir?#

Mimir bridges the gap between your Git provider (GitHub, Bitbucket) and OpenGrok. It wraps the OpenGrok engine in a Docker composition and pairs it with a specialized “brain”—the Mimir Syncer.

Instead of manually cloning repositories or writing ad-hoc cron scripts to git pull changes, Mimir acts as an intelligent agent that actively keeps your local source directory identical to your remote organization’s state.

Key Features#

Mimir isn’t just a simple cron job. It includes logic specifically tailored for modern development workflows:

1. Automated Repository Discovery#

Point Mimir at your GitHub Organization or Bitbucket Workspace, and it will automatically discover every repository you have access to. When a team creates a new microservice, Mimir detects it, clones it, and indexes it without any manual intervention.

2. Smart Branch Prioritization#

In many workflows, the “default” branch isn’t always the one you want to search. You might want to prioritize master for legacy reasons, test for staging verification, or main. Mimir allows you to define a priority list (e.g., ["master", "test", "main"]). For every repo, it checks for these branches in order and checks out the first one it finds. This ensures your search engine reflects the code that actually matters to your deployment.

3. Automatic Reindexing#

Synchronization is only half the battle. Once the code is on the disk, OpenGrok needs to know about it. Mimir automatically triggers OpenGrok’s API to perform a reindex immediately after a sync cycle completes, ensuring your search results are always fresh.

What Can You Do With Mimir?#

Implementing Mimir transforms code search from a manual chore into a reliable infrastructure service.

  • Accelerate Onboarding: New developers can instantly search across the entire organization’s codebase to understand common patterns, utility libraries, and API usages without needing to clone hundreds of repos.
  • Impact Analysis: Planning a breaking change in a shared library? fast, global search allows you to identify every downstream consumer of a function in seconds.
  • Security Audits: Quickly scan your entire organization for deprecated dependencies, hardcoded secrets, or insecure patterns.
  • Legacy Code Spelunking: Navigate complex, historical codebases with OpenGrok’s powerful history and annotation features, now automatically kept up to date.

Getting Started#

Deploying Mimir is straightforward, thanks to its Dockerized architecture.

Prerequisites#

  • Docker and Docker Compose
  • An API Token for your Git Provider (GitHub PAT or Bitbucket App Password)

Configuration#

Mimir is configured entirely via environment variables, making it easy to integrate into infrastructure-as-code workflows.

Create a docker-compose.yml file:

version: "3"

services:
  mimir-syncer:
    image: mimir-syncer:latest
    build: ./syncer # If building locally
    environment:
      - GIT_PROVIDER=github
      - ORG_NAME=my-tech-company
      - API_TOKEN=${GITHUB_TOKEN}
      - SYNC_BRANCH_PRIORITY=master,main,develop
      - SYNC_INTERVAL=3600 # Sync every hour
    volumes:
      - source_code:/src

  opengrok:
    image: opengrok/docker:latest
    ports:
      - "8080:8080"
    volumes:
      - source_code:/opengrok/src

volumes:
  source_code:

Running It#

Simply run:

docker-compose up -d

Mimir will start up, connect to your organization, and begin cloning repositories. You can follow the progress in the logs:

docker-compose logs -f mimir-syncer

Once the initial sync is complete, your OpenGrok instance at http://localhost:8080 will be fully populated and ready for queries.

Conclusion#

Tools like OpenGrok are timeless, but they need modern wrappers to fit into today’s automation-heavy CI/CD world. Mimir provides that modern touch, making code discovery accessible, automatic, and maintenance-free for the whole team.

Check out the project on GitHub to get started.