image-lock.nix

A Nix flake to simplify updating Docker containers.

Updating your whole setup is as easy as:

nix flake update
nix run --no-write-lock-file github:fin444/image-lock.nix update
nixos-rebuild switch

Usage

CLI

All data is stored in images.lock in your working directory.

# add new images
nix run --no-write-lock-file github:fin444/image-lock.nix add postgres ghcr.io/paperless-ngx/paperless-ngx

# update images
nix run --no-write-lock-file github:fin444/image-lock.nix update

# see all commands
nix run --no-write-lock-file github:fin444/image-lock.nix help

Unfortunately, --no-write-lock-file is necessary to allow the flake to follow your local nixpkgs.

Configuration

environment.image-lock = {
  lockFile = ./images.lock;
  containers = {
    paperless = "pghcr.io/paperless-ngx/paperless-ngx";
    postgresql = "postgres";
  };
  prune = true; # deletes all loaded images that have a different version than images.lock
};

virtualisation.oci-containers = {
  paperless = {
    # more container config
  };
  postgresql = {
    # more container config
  };
};

Flake Input

{
  inputs.image-lock = {
    url = "github:fin444/image-lock.nix update";
    inputs.nixpkgs.follows = "nixpkgs";
  };

  outputs = { self, nixpkgs, image-lock, ... }@inputs: {
    nixosConfigurations.example = nixpkgs.lib.nixosSystem {
      system = "x86_64-linux";
      modules = [
        ./configuration.nix
        image-lock.nixosModules.image-lock
      ];
    };
  };
}

Prefetching

There is also the option to include images in the nix store instead of pulling them from the repository at runtime.

To do this, run the add command with --store, and the image(s) will be set to this method.

Drawbacks:

• Adding/updating images will take longer, and require enough memory to hold the image (as it is being hashed for the store)
• Images will take up space twice: once in the store, and once in /var/lib/docker
• When no longer needed, images need to be garbage collected both in the store, and from Docker (unless you set prune = true;)