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mermaid.ink

repository·main·Indexed 42 days ago

https://github.com/jihchi/mermaid.ink

A service that transforms Mermaid diagram syntax into images using a headless browser. Version 16.0.0 supports local installation via pnpm, deployment via Docker, and configuration through environment variables for scaling, timeouts, and PostgreSQL database caching.

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What's inside mermaid.ink

  1. Install and run mermaid.ink locally

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    To run the project from source, clone the repository, install dependencies using pnpm, and start the application. You can use the DEBUG=app:* environment variable to enable debugging for the app namespace.

    git clone https://github.com/jihchi/mermaid.ink.git
cd mermaid.ink
pnpm install
DEBUG=app:* pnpm start

  2. Launch mermaid.ink via Docker

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    You can run mermaid.ink using a Docker container. The default command requires --cap-add=SYS_ADMIN to function, but this is generally not recommended for security reasons.

    Secure alternatives

    1. Using a custom seccomp profile Instead of using SYS_ADMIN, you can use Jessie Frazelle's seccomp profile for Chrome:

    wget https://raw.githubusercontent.com/jfrazelle/dotfiles/master/etc/docker/seccomp/chrome.json
docker run --security-opt seccomp=$(pwd)/chrome.json ghcr.io/jihchi/mermaid.ink

    2. Running without a seccomp profile If you encounter core dump errors during startup, you can run the container without a seccomp profile:

    docker run --security-opt seccomp=unconfined ghcr.io/jihchi/mermaid.ink

    3. Default (Not recommended)

    docker run --cap-add=SYS_ADMIN -p 3000:3000 ghcr.io/jihchi/mermaid.ink

  3. Configure mermaid.ink via environment variables

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    The following environment variables can be used to configure the behavior of the mermaid.ink service:

    variable namedefault valuedescription
    MAX_WIDTH10000Maximum scaled diagram width allowed.
    MAX_HEIGHT10000Maximum scaled diagram height allowed.
    FONT_AWESOME_CSS_URL<unset>Custom URL for injected Font-Awesome CSS. Use FA_VERSION as a placeholder for the version (e.g., https://.../FA_VERSION/css/all.min.css).
    PROTOCOL_TIMEOUT180000Timeout for individual CDP (Chrome DevTools Protocol) calls.
    HEADLESS_MODE'true'Browser mode: 'true' (new headless), 'shell' (old headless/chrome-headless-shell).
    QUEUE_CONCURRENCY1Maximum number of concurrent rendering jobs.
    QUEUE_ADD_TIMEOUT3000Timeout in milliseconds for a rendering job.
    ENABLE_DATABASE<unset>Set to 'true' to enable PostgreSQL database caching.
    PGHOST<unset>PostgreSQL server hostname.
    PGPORT<unset>PostgreSQL server port.
    PGDATABASE<unset>PostgreSQL database name.
    PGUSERNAME<unset>PostgreSQL username.
    PGPASSWORD<unset>PostgreSQL password

  4. Start the mermaid.ink server

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    The mermaid.ink server is bootstrapped by initializing a Koa application that includes a Puppeteer browser instance, a job queue, and an optional database connection. By default, the server listens on port 3000, but this can be configured using the PORT environment variable.

    # Run with default port 3000
node src/index.js

# Run on a custom port
PORT=8080 node src/index.js

  5. Fix HTTP 431 Request Header Fields Too Large error

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    If you encounter the HTTP 431 Request Header Fields Too Large error, you must increase the --max-http-header-size limit.

    Warning: Increasing this limit may expose the service to Denial of Service (DoS) attacks.

    Local execution

    Set the NODE_OPTIONS environment variable:

    NODE_OPTIONS="--max-http-header-size=102400000" npm start

    Docker execution

    Pass the NODE_OPTIONS via the -e flag:

    docker run --rm -it -e 'NODE_OPTIONS="--max-http-header-size=102400000"' -p 3000:3000 ghcr.io/jihchi/mermaid.ink