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Overview

Provides a Node.js generator to produce Dockerfiles and related files. It is intended to support any framework that lists its dependencies, includes a start script in package.json, and optionally includes a build script.

See test for a list of frameworks and examples of Dockerfiles produced based on the associated package.json and lock files.

See blog post for more information.

Usage

To run once:

npx --yes @flydotio/dockerfile@latest
bunx --bun @flydotio/dockerfile@latest

Or install it with your favorite package manager:

bun add -d @flydotio/dockerfile
npm install @flydotio/dockerfile --save-dev
pnpm add -D @flydotio/dockerfile
yarn add @flydotio/dockerfile --dev

Once installed, you can run and re-run using npx dockerfile for Node.js applications or bunx --bun dockerfile for Bun applications.

Options are saved between runs into package.json. To invert a boolean options, add or remove a no- prefix from the option name.

Options:

  • --alpine - use alpine as base image
  • --build=CMD - command to be used to build your application.
  • --cache - use build caching to speed up builds
  • --cmd=CMD - CMD to use in Dockerfile
  • --defer-build - may be needed when your build step requires access to secrets that are not available at image build time. Results in larger images and slower deployments.
  • --dev - include devDependencies in the production image.
  • --distroless - use distroless base image to reduce image size
  • --entrypoint - ENTRYPOINT to use in Dockerfile
  • --ignore-scripts - do not execute any scripts defined in the project package.json and its dependencies.
  • --force - overwrite existing files
  • --legacy-peer-deps - ignore peer dependencies.
  • --litefs - configure and enable litefs.
  • --nginxRoot=DIR - serve static files from given directory via nginx.
  • --link - Add --link to COPY statements. Some tools, including buildah) or Buildkit don't properly support this feature.
  • --port=n - expose port (default may vary based on framework, but otherwise is 3000)
  • --swap=n - allocate swap space. See falloc options for suffixes
  • --windows - make Dockerfile work for Windows users that may have set git config --global core.autocrlf true.

Add a package/environment variable/build argument:

Not all of your needs can be determined by scanning your application. For example, I like to add vim and procps.

  • --add package... - add one or more debian packages
  • --arg=name:value - add a build argument
  • --env=name:value - add an environment variable
  • --remove package... - remove package from "to be added" list

Args and environment variables can be tailored to a specific build phase by adding -base, -build, or -deploy after the flag name (e.g --add-build freetds-dev --add-deploy freetds-bin). If no such suffix is found, the default for arg is -base, and the default for env is -deploy. Removal of an arg or environment variable is done by leaving the value blank (e.g --env-build=PORT:).

Build secrets

Techniques such as static site generation using databases may require access to secrets at build time. To enable this you will need to mount the secret:

  • --mount-secret=name - add name to the list of secrets to mount when running the build script
  • --unmount-secret-name - remove name from the list of secrets to mount when running the build script

See Secret to expose to the build for examples on how to pass secrets to a docker build.

Advanced customization

There may be times where feature detection plus flags just aren't enough. As an example, you may wish to configure and run multiple processes.

  • --instructions=path - a dockerfile fragment to be inserted into the final document.

Like with environment variables, packages, and build args, --instructions can be tailored to a specific build phase by adding -base, -build, or -deploy after the flag name, with the default being -deploy.

Platform specific processing

In addition to creating Dockerfiles and associated artifacts, dockerfile-node can run platform specific processing. At the present time the first and only platform taking advantage of this is naturally fly.io.

If, and only if, flyctl is installed, part of the path, and there exists a valid fly.toml file in the current directory, dockerfile-node will:

  • configure and create volume(s) for sqlite3
  • set swapfile size if that option is selected
  • attach consul for litefs
  • set secrets for remix and adonis apps
  • initialize git
  • define a staging app if one is mentioned in .github/workflows/deploy.yml

Testing

A single invocation of npm test will run all of the tests defined. Additionally npm run eslint will run eslint.

The current integration testing strategy is to run the dockerfile generator against various configurations and compare the generated artifacts with expected results. ARG values in Dockerfiles are masked before comparison.

To assist with this process, outputs of tests can be captured automatically. This is useful when adding new tests and when making a change that affects many tests. Be sure to inspect the output (e.g., by using git diff) before committing.

npm run test:capture

To run a single test (or tests maching a pattern), run mocha directly with the grep option.

npx mocha --grep swap

Additionally, each the outputs in each test directory can be directly tested to ensure that they can be successfully built by running docker buildx directory passing in the necessary build arguments. For example:

docker buildx build . --build-arg NODE_VERSION=18