This GitHub Action utilizes Nixpacks to build your application into a Docker image and then pushes the image to a Docker registry. Nixpacks generates an OCI-compliant container image from your application source without the need for a Dockerfile.

• Nixpacks Integration: Leverages Nixpacks for building OCI-compliant Docker images from application source.
• Flexible Tagging: Allows multiple tags to be specified for the built image.
• Metadata Addition: Supports adding labels to the Docker image.
• Platform Specification: Enables building for specific target platforms.
• Package Inclusion: Offers the capability to include additional Nix and Apt packages in the build environment.

• context: The build's context, specifying the set of files located at the provided PATH. It is required to point to your application source code.
• tags: A comma-separated list of tags to apply to the built image. This field is required.
• labels: An optional, comma-separated list of metadata labels to add to the image.
• platforms: An optional, comma-separated list of target platforms for the build.
• pkgs: Optional additional Nix packages to install in the environment.
• apt: Optional additional Apt packages to install in the environment.
• env-file: An optional, specifying environtment file to add to the image, located at the provided PATH.
• env: An optional, comma-separated list of environtment key=value to add to the image. (env variables will overwrite the variables in env-file if the key are the same.)
• push: An optional, boolean value to specify the result image should be pushed or not. Default to false. (if true, need to login to registry first using docker/login-action or etc.)

To use this action in your workflow, add the following step:

- uses: WaxArsatia/nixpacks-build-push-action
  with:
    context: './path-to-app'
    tags: 'latest,stable'
    labels: 'version=1.0,framework=express'
    platforms: 'linux/amd64,linux/arm64'
    pkgs: 'nodejs,npm'
    apt: 'curl,git'
    env-file: '.env'
    env: 'SECRET_KEY=XXX'
    push: false

Ensure that your GitHub Actions runner has Docker installed and configured correctly, especially if you're pushing to a private registry.

The action automatically installs Nixpacks if it's not already present in the environment. Then, it constructs and executes a Nixpacks build command using the provided inputs. After the build, it pushes the tagged image(s) to the Docker registry.

• The tags input is required to identify the image(s) in the registry uniquely.
• If labels or platforms are specified, they are added to the build command to include in the Docker image.
• Additional Nix or Apt packages can be specified through pkgs and apt inputs to customize the build environment.
• If env-file or env are specified, they are added to the build image as environtment variables
• If push is set to true, then need to make sure workflows already login (have privilege) to push image to registry

This GitHub Action simplifies the process of building and deploying containerized applications by leveraging the power of Nixpacks, making it easier to integrate into CI/CD pipelines without the need for Dockerfiles.