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https://github.com/aksiksi/compose2nix

Generate a NixOS config from a Docker Compose project.
https://github.com/aksiksi/compose2nix
containers docker docker-compose nix nixos podman podman-compose
Last synced: 4 days ago
JSON representation
Generate a NixOS config from a Docker Compose project.
Host: GitHub
URL: https://github.com/aksiksi/compose2nix
Owner: aksiksi
License: mit
Created: 2023-11-01T01:22:49.000Z (about 1 year ago)
Default Branch: main
Last Pushed: 2024-11-25T12:45:06.000Z (17 days ago)
Last Synced: 2024-12-01T00:10:27.644Z (11 days ago)
Topics: containers, docker, docker-compose, nix, nixos, podman, podman-compose
Language: Go
Homepage:
Size: 390 KB
Stars: 391
Watchers: 6
Forks: 4
Open Issues: 9
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project

awesome-nix - compose2nix - Generate a NixOS config from a Docker Compose project. (Development / Discovery)
README

        # compose2nix

[![Test](https://github.com/aksiksi/compose2nix/actions/workflows/test.yml/badge.svg)](https://github.com/aksiksi/compose2nix/actions/workflows/test.yml)

[![NixOS](https://github.com/aksiksi/compose2nix/actions/workflows/nixos.yml/badge.svg)](https://github.com/aksiksi/compose2nix/actions/workflows/nixos.yml)

[![codecov](https://codecov.io/gh/aksiksi/compose2nix/graph/badge.svg)](https://codecov.io/gh/aksiksi/compose2nix)

[![Go Reference](https://pkg.go.dev/badge/github.com/aksiksi/compose2nix.svg)](https://pkg.go.dev/github.com/aksiksi/compose2nix)

A tool to automatically generate a NixOS config from a Docker Compose project.

## Overview

### Intro video

[![Rambly introduction video](https://img.youtube.com/vi/hCAFyzJ81Pg/hqdefault.jpg)](https://youtu.be/hCAFyzJ81Pg)

### Why?

Running a Docker Compose stack/project on NixOS is not well supported. One approach is to define a systemd service that runs `docker-compose up` on start and `docker compose down` on stop.

But with this approach, changes to individual services are not visible to NixOS, which means that NixOS will need to restart the systemd service on **any** change to the Compose file. This can be mitigated by defining a systemd reload handler, but it still is finicky to work with and will always remain opaque to NixOS.

To top it all off, using Docker Compose on NixOS is fairly redundant as the features you get with Compose are available natively on NixOS.

### How?

`compose2nix` takes your existing Docker Compose file(s) and converts each YAML service definition into a [`oci-container`](https://search.nixos.org/options?query=virtualisation.oci-containers) config. The tool also sets up systemd services to create all networks and volumes that are part of the Compose project. Since `compose2nix` uses the same library that the Docker CLI relies on under the hood, you also get Compose file validation and syntax checking "for free".

### Benefits

1. Supports both Docker and Podman out of the box.

2. Each Compose service maps into a systemd service that is natively managed by NixOS.

3. A change to one container service only impacts that container and any of its dependents.

4. Generated systemd services can be extended from your NixOS config.

5. `compose2nix` supports setting additional systemd service and unit options through Docker Compose labels (search for the `compose2nix.systemd.` label in the samples).

## Quickstart

Install the `compose2nix` CLI via one of the following methods:

1. Run using `nix run` (**recommended**):

    ```

    # Latest

    nix run github:aksiksi/compose2nix -- -h

    # Specific version

    nix run github:aksiksi/compose2nix/v0.3.0 -- -h

    # Specific commit

    nix run github:aksiksi/compose2nix/0c38d282d6662fc902fca7ef5b33e889f9e3e59a -- -h

    ```

2. Install from `nixpkgs`:

    ```

    # NixOS config

    environment.systemPackages = [

      pkgs.compose2nix

    ];

    ```

3. Add the following to your `flake.nix`:

    ```nix

    compose2nix.url = "github:aksiksi/compose2nix";

    compose2nix.inputs.nixpkgs.follows = "nixpkgs";

    ```

    Optionally, you can pin to a specific version:

    ```nix

    compose2nix.url = "github:aksiksi/compose2nix/v0.3.0";

    ```

    You can then install the package by adding the following to your NixOS config:

    ```nix

    environment.systemPackages = [

      inputs.compose2nix.packages.x86_64-linux.default

    ];

    ```

Run `compose2nix`. Note that project must either be passed in **or** set in the Compose file's top-level "name".

```bash

compose2nix -project=myproject

```

By default, the tool looks for `docker-compose.yml` in the **current directory** and outputs the NixOS config to `docker-compose.nix`.

## Roadmap

- [x] Basic implementation

- [x] Support for most common Docker Compose features

- [x] Support for using secret environment files

## Docs

### Sample

* Input: https://github.com/aksiksi/compose2nix/blob/main/testdata/compose.yml

* Output (Docker): https://github.com/aksiksi/compose2nix/blob/main/testdata/TestBasic.docker.nix

* Output (Podman): https://github.com/aksiksi/compose2nix/blob/main/testdata/TestBasic.podman.nix

### Working with Secrets

#### [agenix](https://github.com/ryantm/agenix)

`agenix` works by decrypting secrets and placing them in `/run/agenix/`. To feed this into your Nix config:

1. Place all secret env variables in the encrypted env file (e.g., `my-env-file.env`).

2. Mark the decrypted env file as readable by the user running `compose2nix`.

3. Run `compose2nix` with the env file path(s) and set `-include_env_files=true`:

   ```

   compose2nix --env_files=/run/agenix/my-env-file.env --include_env_files=true

   ```

> [!NOTE]

> If you also want to ensure that you only include env files in the output Nix config, set `-env_files_only=true`.

### Patterns

In this case, the project is called `myproject` and the service name is `myservice`. Replace `podman` with `docker` if using the Docker runtime.

#### List all services

```

sudo systemctl list-units podman-*

```

#### List all services in a project

```

sudo systemctl list-units *myservice*

```

#### Restart a service

Note: if the Compose service has a `container_name` set, then the systemd service will not include the project name.

```

sudo systemctl restart podman-myproject-myservice.service

```

#### Update a Container

1. Pull the latest image for the container (requires [`jq`](https://jqlang.github.io/jq/)):

```

sudo podman pull $(sudo podman inspect myproject-myservice | jq -r .[0].ImageName)

```

2. Restart the service:

```

sudo systemctl restart podman-myproject-myservice.service

```

#### **Podman**: Auto-update containers

1. Add a `io.containers.autoupdate=registry` label to each Compose service you want to have auto-updated.

    * Make sure to use a **fully-qualified** image path (e.g., `docker.io/repo/image`). Otherwise, Podman will fail to start the container.

2. Run `sudo podman auto-update --dry-run` to see which containers would get updated. Omit `--dry-run` to update & restart services.

You can optionally enable a Podman-provided timer that runs the command above once per day at midnight (by default):

```nix

# Enable the existing timer unit.

systemd.timers."podman-auto-update".wantedBy = [ "timers.target" ];

```

See this page for details: https://docs.podman.io/en/latest/markdown/podman-auto-update.1.html

#### Auto-start services on boot

By default, all generated services will be started by systemd on boot.

You can override this behavior in two different ways:

1. **Disable auto-start for all services:** Re-generate your config with `-auto_start=false`.

2. **Disable or enable auto-start for a single service:** Add a Compose label to your service like this:

    ```yaml

    services:

      my-service:

        labels:

          # Enable

          - "compose2nix.settings.autoStart=true"

          # Disable

          - "compose2nix.settings.autoStart=false"

    ```

#### `docker compose down`

By default, this will only remove networks.

```

sudo systemctl stop podman-compose-myservice-root.target

```

##### Remove volumes

You can do one of the following:

1. Re-generate your NixOS config with: `-remove_volumes=true`

2. Run `sudo podman volume prune` to manually cleanup unreferenced volumes

#### `docker compose up`

```

sudo systemctl start podman-compose-myservice-root.target

```

#### Compose Build spec

`compose2nix` has basic support for the Build spec. See [Supported Compose Features] below for details.

By default, a systemd service will be generated for _each_ container build. This is a

one-shot service that simply runs the build when started.

For example, if you have a service named `my-service` with a `build` set:

```

sudo systemctl start podman-build-my-service.service

```

Note that, until this is run, the container for `my-service` will **not be able to start** due to the missing image.

##### Auto-build

If you run the CLI with `-build=true`, the systemd service will be marked as a dependency for the service

container. This means that the build will be run before the container is started.

However, it is important to note that the build will be re-run on every restart of the root target or system.

This will result in the build image being updated (potentially).

### Nvidia GPU Support

1. Enable CDI support in your NixOS config:

```nix

{

  hardware.nvidia-container-toolkit.enable = true;

}

```

**Docker only:**

Make sure you are running Docker 25+:

```nix

{

  virtualisation.docker.package = pkgs.docker_25;

}

```

2. Pass in CDI devices via either `devices` **or** `deploy` (both map to the same thing under the hood):

```yaml

services:

  myservice:

    # ... other fields

    # Option 1

    devices:

      - nvidia.com/gpu=all

    # Option 2

    deploy:

      resources:

        reservations:

          devices:

            # Driver must be set to "cdi" - all others are ignored.

            - driver: cdi

              device_ids:

                - nvidia.com/gpu=all

    # Required for Podman.

    security_opt:

      - label=disable

```

### NixOS Version Support Policy

I always aim to support the **latest** stable version of NixOS (24.05 at the

time of writing). As a result, some NixOS unstable options are not used.

If the option has a strong usecase, I am open to adding a CLI flag that can be

deprecated once the option is stable.

### Known Issues

#### Docker & multiple networks

If you are using the Docker runtime and a Compose service connects to multiple networks, you'll need to use v25+. Otherwise, the container service will fail to start.

You can pin the Docker version to v25 like so:

```nix

{

  virtualisation.docker.package = pkgs.docker_25;

}

```

Discussion: https://github.com/aksiksi/compose2nix/issues/24

#### Podman: Port forwarding in `internal` networks

For some reason, when you run a *rootful* Podman container in a network that is marked as `internal`, port forwarding to the host does not work. Podman seems to completely isolate the network from the external world - including the host network! Note that Docker claims to support this behavior out-of-the-box ([ref](https://docs.docker.com/reference/cli/docker/network/create/#internal)).

There is a workaround: remove the `internal` setting and set the network driver option `no_default_route=1` ([example](https://github.com/aksiksi/compose2nix/discussions/39#discussioncomment-10717015)).

```yaml

networks:

  my-network:

    driver: bridge

    driver_opts:

      no_default_route: 1 # <<< This is what prevents external network access.

    ipam:

      config:

        - subnet: 10.8.1.0/24

          gateway: 10.8.1.0

```

This will allow you to connect from the host, while also preventing internet access from within the container. 

This is where the check is done in Netavark: [link](https://github.com/containers/netavark/blob/cebebc70daec7010c4005798a7958b3b6be7151d/src/network/bridge.rs#L756)

### Usage

```

$ compose2nix -h

Usage of compose2nix:

  -auto_format

    	if true, Nix output will be formatted using "nixfmt" (must be present in $PATH).

  -auto_start

    	auto-start setting for generated service(s). this applies to all services, not just containers. (default true)

  -check_systemd_mounts

    	if set, volume paths will be checked against systemd mount paths on the current machine and marked as container dependencies.

  -create_root_target

    	if set, a root systemd target will be created, which when stopped tears down all resources. (default true)

  -default_stop_timeout duration

    	default stop timeout for generated container services. (default 1m30s)

  -env_files string

    	one or more comma-separated paths to .env file(s).

  -env_files_only

    	only use env file(s) in the NixOS container definitions.

  -generate_unused_resources

    	if set, unused resources (e.g., networks) will be generated even if no containers use them.

  -ignore_missing_env_files

    	if set, missing env files will be ignored.

  -include_env_files

    	include env files in the NixOS container definition.

  -inputs string

    	one or more comma-separated path(s) to Compose file(s). (default "docker-compose.yml")

  -output string

    	path to output Nix file. (default "docker-compose.nix")

  -project string

    	project name used as a prefix for generated resources. this overrides any top-level "name" set in the Compose file(s).

  -remove_volumes

    	if set, volumes will be removed on systemd service stop.

  -root_path string

    	root path to use for any relative paths in the Compose file (e.g., volumes). if unset, the current working directory will be used.

  -runtime string

    	one of: ["podman", "docker"]. (default "podman")

  -service_include string

    	regex pattern for services to include.

  -use_compose_log_driver

    	if set, always use the Docker Compose log driver.

  -use_upheld_by

    	if set, upheldBy will be used for service dependencies (NixOS 24.05+).

  -version

    	display version and exit

  -write_nix_setup

    	if true, Nix setup code is written to output (runtime, DNS, autoprune, etc.) (default true)

```

### Supported Compose Features

If a feature is missing, please feel free to [create an issue](https://github.com/aksiksi/compose2nix/issues/new). In theory, any Compose feature can be supported because `compose2nix` uses the same library as the Docker CLI under the hood.

#### [`services`](https://docs.docker.com/compose/compose-file/05-services/)

|   |     | Notes |

|---|:---:|-------|

| [`image`](https://docs.docker.com/compose/compose-file/05-services/#image) | ✅ | |

| [`container_name`](https://docs.docker.com/compose/compose-file/05-services/#container_name) | ✅ | |

| [`environment`](https://docs.docker.com/compose/compose-file/05-services/#environment) | ✅ | |

| [`env_file`](https://docs.docker.com/compose/compose-file/05-services/#env_file) | ✅ | |

| [`volumes`](https://docs.docker.com/compose/compose-file/05-services/#volumes) | ✅ | |

| [`labels`](https://docs.docker.com/compose/compose-file/05-services/#labels) | ✅ | |

| [`ports`](https://docs.docker.com/compose/compose-file/05-services/#ports) | ✅ | |

| [`dns`](https://docs.docker.com/compose/compose-file/05-services/#dns) | ✅ | |

| [`cap_add/cap_drop`](https://docs.docker.com/compose/compose-file/05-services/#cap_add) | ✅ | |

| [`logging`](https://docs.docker.com/compose/compose-file/05-services/#logging) | ✅ | |

| [`depends_on`](https://docs.docker.com/compose/compose-file/05-services/#depends_on) | ⚠️  | Only short syntax is supported. |

| [`restart`](https://docs.docker.com/compose/compose-file/05-services/#restart) | ✅ | |

| [`deploy.restart_policy`](https://docs.docker.com/compose/compose-file/deploy/#restart_policy) | ✅ | |

| [`deploy.resources.limits`](https://docs.docker.com/compose/compose-file/deploy/#resources) | ✅ | |

| [`deploy.resources.reservations.cpus`](https://docs.docker.com/compose/compose-file/deploy/#cpus) | ✅ | |

| [`deploy.resources.reservations.memory`](https://docs.docker.com/compose/compose-file/deploy/#memory) | ✅ | |

| [`deploy.resources.reservations.devices`](https://docs.docker.com/compose/compose-file/deploy/#devices) | ⚠️  | Only CDI driver is supported. |

| [`devices`](https://docs.docker.com/compose/compose-file/05-services/#devices) | ✅ | |

| [`networks.aliases`](https://docs.docker.com/compose/compose-file/05-services/#aliases) | ✅ | |

| [`networks.ipv*_address`](https://docs.docker.com/compose/compose-file/05-services/#ipv4_address-ipv6_address) | ✅ | |

| [`network_mode`](https://docs.docker.com/compose/compose-file/05-services/#network_mode) | ✅ | |

| [`privileged`](https://docs.docker.com/compose/compose-file/05-services/#privileged) | ✅ | |

| [`extra_hosts`](https://docs.docker.com/compose/compose-file/05-services/#extra_hosts) | ✅ | |

| [`sysctls`](https://docs.docker.com/compose/compose-file/05-services/#sysctls) | ✅ | |

| [`shm_size`](https://docs.docker.com/compose/compose-file/05-services/#shm_size) | ✅ | |

| [`runtime`](https://docs.docker.com/compose/compose-file/05-services/#runtime) | ✅ | |

| [`security_opt`](https://docs.docker.com/compose/compose-file/05-services/#security_opt) | ✅ | |

| [`command`](https://docs.docker.com/compose/compose-file/05-services/#command) | ✅ | |

| [`entrypoint`](https://docs.docker.com/compose/compose-file/05-services/#entrypoint) | ✅ | |

| [`healthcheck`](https://docs.docker.com/compose/compose-file/05-services/#healthcheck) | ✅ | |

| [`hostname`](https://docs.docker.com/compose/compose-file/05-services/#hostname) | ✅ | |

| [`mac_address`](https://docs.docker.com/compose/compose-file/05-services/#mac_address) | ✅ | |

| [`user`](https://docs.docker.com/compose/compose-file/05-services/#user) | ✅ | |

#### [`networks`](https://docs.docker.com/compose/compose-file/06-networks/)

|   |     |

|---|:---:|

| [`labels`](https://docs.docker.com/compose/compose-file/06-networks/#labels) | ✅ |

| [`name`](https://docs.docker.com/compose/compose-file/06-networks/#name) | ✅ |

| [`driver`](https://docs.docker.com/compose/compose-file/06-networks/#driver) | ✅ |

| [`driver_opts`](https://docs.docker.com/compose/compose-file/06-networks/#driver_opts) | ✅ |

| [`enable_ipv6`](https://docs.docker.com/compose/compose-file/06-networks/#enable_ipv6) | ✅ |

| [`ipam`](https://docs.docker.com/compose/compose-file/06-networks/#ipam) | ✅ |

| [`external`](https://docs.docker.com/compose/compose-file/06-networks/#external) | ✅ |

| [`internal`](https://docs.docker.com/compose/compose-file/06-networks/#internal) | ✅ |

#### [`volumes`](https://docs.docker.com/compose/compose-file/07-volumes/)

|   |     |

|---|:---:|

| [`driver`](https://docs.docker.com/compose/compose-file/07-volumes/#driver) | ✅ |

| [`driver_opts`](https://docs.docker.com/compose/compose-file/07-volumes/#driver_opts) | ✅ |

| [`labels`](https://docs.docker.com/compose/compose-file/07-volumes/#labels) | ✅ |

| [`name`](https://docs.docker.com/compose/compose-file/07-volumes/#name) | ✅ |

| [`external`](https://docs.docker.com/compose/compose-file/07-volumes/#external) | ✅ |

#### [`build`](https://docs.docker.com/reference/compose-file/build/)

|   |     | Notes |

|---|:---:|-------|

| [`args`](https://docs.docker.com/reference/compose-file/build/#args) | ✅ | |

| [`tags`](https://docs.docker.com/reference/compose-file/build/#tags) | ✅ |

| [`context`](https://docs.docker.com/reference/compose-file/build/#context) | ⚠️  | Git repo is not supported |

| [`network`](https://docs.docker.com/reference/compose-file/build/#network) | ❌ |

| [`image`+`build`](https://docs.docker.com/reference/compose-file/build/#using-build-and-image) | ❌ |

#### Misc

* [`name`](https://docs.docker.com/compose/compose-file/04-version-and-name/#name-top-level-element) - ✅

### Alternative Installation Methods

1. Use in a Nix shell:

    ```bash

    nix shell github:aksiksi/compose2nix

    ```

2. Install the command using `go`:

    ```

    go install github.com/aksiksi/compose2nix

    ```

3. Clone this repo and run `make build`.