depot/third_party/nixpkgs/doc/builders/images/ocitools.section.md

pkgs.ociTools

pkgs.ociTools is a set of functions for creating containers according to the OCI container specification v1.0.0. Beyond that it makes no assumptions about the container runner you choose to use to run the created container.

buildContainer

This function creates a simple OCI container that runs a single command inside of it. An OCI container consists of a config.json and a rootfs directory.The nix store of the container will contain all referenced dependencies of the given command.

The parameters of buildContainer with an example value are described below:

buildContainer {
  args = [
    (with pkgs;
      writeScript "run.sh" ''
        #!${bash}/bin/bash
        exec ${bash}/bin/bash
      '').outPath
  ];

  mounts = {
    "/data" = {
      type = "none";
      source = "/var/lib/mydata";
      options = [ "bind" ];
    };
  };

  readonly = false;
}

• args specifies a set of arguments to run inside the container. This is the only required argument for buildContainer. All referenced packages inside the derivation will be made available inside the container

• mounts specifies additional mount points chosen by the user. By default only a minimal set of necessary filesystems are mounted into the container (e.g procfs, cgroupfs)

• readonly makes the container's rootfs read-only if it is set to true. The default value is false false.