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Containers

makeContainerImage

Build a container image in OCI Format.

A container image is composed of:

  • 0 or more layers (binary blobs).
    • Each layer contains a snapshot of the root file system (/), they represent portions of it.
    • When the container is executed all layers are squashed together to compose the root of the file system (/).
  • A JSON manifest (metadata) that describes important aspects of the container, for instance its layers, environment variables, entrypoint, etc.

Resources:

Types:

  • makeContainerImage (function { ... } -> package):
    • layers (listOf package): Optional. Layers of the container. Defaults to [ ].
    • maxLayers (ints.positive): Optional. Maximum number of layers the container can have. Defaults to 65.
    • config (attrsOf anything): Optional. Configuration manifest as described in OCI Runtime Configuration Manifest Defaults to { }.

Example:

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{ inputs, makeContainerImage, makeDerivation, ... }:
{
  jobs."/myContainer" = makeContainerImage {
    config = {
      Env = [
        # Do not use this for sensitive values, it's not safe.
        "EXAMPLE_ENV_VAR=example-value"
      ];
      WorkingDir = "/working-dir";
    };
    layers = [
      inputs.nixpkgs.coreutils # ls, cat, etc
      (makeDerivation {
        name = "custom-layer";
        builder = ''
          # $out represents the final container root file system: /
          #
          # The following commands are equivalent in Docker to:
          #   RUN mkdir /working-dir
          #   RUN echo my-file-contents > /working-dir/my-file
          #
          mkdir -p $out/working-dir
          echo my-file-contents > $out/working-dir/my-file
        '';
      })
    ];
  };
}