Docker rootless Ansible role

An Ansible role to configure install and configure a Docker daemon running as a non-root user.

Do not use any of this without first testing in a non-operational environment.

Rootless mode allows running the Docker daemon and containers as a non-root user to mitigate potential vulnerabilities in the daemon and the container runtime. (docker)

Note There is a SLSA artifact present under the slsa action workflow for verification.

Requirements

---
roles:
  - name: konstruktoid.docker_rootless
    version: v1.0.0
    src: https://github.com/konstruktoid/ansible-role-docker-rootless.git
    scm: git

Playbook example

---
- hosts: all
  any_errors_fatal: true
  tasks:
    - name: Include the konstruktoid.docker_rootless role
      ansible.builtin.import_role:
        name: konstruktoid.docker_rootless

Role Variables with defaults

---
configure_sysctl: true
create_docker_user: true
install_dependencies: true

docker_arch: "{{ ansible_facts.architecture }}"
docker_add_alias: true
docker_allow_ping: false
docker_allow_privileged_ports: false
docker_compose: false
docker_compose_release: v2.39.2
docker_compose_url: https://github.com/docker/compose/releases/download
docker_daemon_json_template: daemon.json.j2
docker_driver_network: slirp4netns
docker_driver_port: builtin
docker_release: 28.4.0
docker_repository_template: docker.repo.j2
docker_rootful_enabled: false
docker_rootful: false
docker_rootful_opts: false
docker_rootful_service_template: docker_rootful.service.j2
docker_rootless_script_template: docker_rootless.sh.j2
docker_rootless_service_template: docker_rootless.service.j2
docker_service_restart: true
docker_unattended_upgrades: false
docker_url: "https://download.docker.com/linux/static/stable/{{ docker_arch }}"
docker_user_bashrc: false
docker_user: dockeruser
shasums:
  docker_release:
    x86_64: 21516934188f06d0e5f232cbde8112701f6d82899016240bc7a5d619f6b0059c
    aarch64: 059416f4fe7465bdedbabd6d34db524e6e3bef65f3b61caa42a3d8ca94150ed2
  docker_rootless_release:
    x86_64: f38cbd2b7d780ce8be17c12f596af6df596901acb2725cea10748b71f201e36e
    aarch64: 39d333a944a133b6d37d5f9fc13ea09c3e194538b1c6331ba965bf39e7212e46
  docker_compose_release:
    x86_64: a55a8cd4ef103aac282812554e531aac8df7e914a287ee81e14d695556a22902
    aarch64: 54488fffb60782f3c8787a48b95ed15f49f5a3a85f4105304bd46db5edd9db61

Before using this role you first have to decide if you want to install Docker using the packages available to the distribution, also known as the "rootful" installation since it requires root permissions and installs the upstream Docker daemon or if you want to download the static binaries and do a manual install.

If you run the role on a system without having root permissions, you will need to set configure_sysctl: false, create_docker_user: false and install_dependencies: false and ensure that the system has the required dependencies installed and the docker user created beforehand.

If you set docker_rootful: false you will download the static binaries and do a manual install, not requiring any root permissions.

If docker_rootful: true, then docker_rootful_enabled will decide if the daemon should be enabled as a service or not.

docker_service_restart will restart the rootless service after the Docker binaries has been extracted. This may affect any running containers.

Using docker_rootful: true and docker_rootful_enabled: true, will result in a standard Docker installation, with an additional Docker daemon, running as a non-root user.

Note that Debian 10 and earlier requires docker_rootful: false due to missing dependencies.

The docker_url, docker_release, docker_compose_url and docker_compose_release variables define where you find the relevant binaries and which version you should use when doing a manual installation.

You define the name of the Docker user that will be created with the docker_user variable. This user will download and install the binaries if docker_rootful: false or else the user will be the one running the rootless installation script and starting a isolated daemon.

Note that the sole purpose of the docker_user is to run the Docker daemon and related containers, and not for system administration or used as a regular user.

docker_release_shasum, docker_release_rootless_shasum and docker_compose_release_shasum are used to verify the files when downloaded using the get_url module. The docker_release_shasum is used for the Docker .tgz file and docker_release_rootless_shasum for the docker-ce-rootless-extras package.

docker_rootful_opts is the options to apply to the Docker daemon if running in rootful mode, if unset the settings in docker_rootful_service_template will be used.

If docker_add_alias: true, then a docker alias will be added to either .bashrc or .bash_aliases of the Ansible user. If false, a shell script named docker_rootless.sh is created in the Ansible user home directory. This works as a substitute to the docker command so that the Ansible user can execute the rootless Docker installation from the docker_user.

If docker_compose: true, then the Docker compose plugin or docker-compose will be installed. docker_compose_arch are used to define the architecture of the docker-compose binary.

If docker_user_bashrc: true, a .bashrc with completion for the docker and docker compose command will be placed inside the docker_user home.

If docker_unattended_upgrades: true and the unattended-upgrades package is installed, the docker and docker-compose binaries will be updated automatically.

The docker_allow_privileged_ports variable configures if exposing privileged ports (< 1024) is allowed.

The docker_allow_ping variable configures if unprivileged users can open ICMP echo sockets. On some distributions, this is not allowed, and thereby containers cannot ping to the outside.

The docker_driver_network and docker_driver_port variables configure RootlessKit's network driver or port driver, respectively. This is useful for optimising network performance and necessary if source IP propagation is required. By default, the builtin port driver does not expose the actual source IP; instead, all connections appear to the container as originating from the Docker gateway (e.g. 172.19.0.1). Set docker_driver_port: slirp4netns to enable source IP propagation.

The variables named *_template are the locations of the templates in use, this to make it easier to replace them with custom ones.

The most important template is most likely docker_daemon_json_template: daemon.json.j2, which is the location of the Docker daemon.json configuration file template.

Container management

Standalone container

Running containers is not that much different from when a rootful Docker daemon is used, but you still need to become the unprivileged user and adapt any paths to the user working directores.

If docker_add_alias: true is used, the docker command will be available as usual for the Ansible user, too. Type alias in the shell to see the keyword configuration.

- name: Register Docker user info
  become: true
  ansible.builtin.user:
    name: "{{ docker_user }}"
  check_mode: true
  register: docker_user_info

- name: Example container block
  environment:
    XDG_RUNTIME_DIR: "/run/user/{{ docker_user_info.uid }}"
    PATH: "{{ docker_user_info.home }}/bin:{{ ansible_env.PATH }}"
    DOCKER_HOST: "unix:///run/user/{{ docker_user_info.uid }}/docker.sock"
  block:
    - name: Nginx container
      become: true
      become_user: "{{ docker_user }}"
      community.docker.docker_container:
        name: nginx
        image: konstruktoid/nginx
        state: started
        cap_drop: all
        capabilities:
          - chown
          - dac_override
          - net_bind_service
          - setgid
          - setuid
        pull: true
        hostname: "{{ ansible_nodename }}"
        container_default_behavior: compatibility

Docker compose service

- name: Register Docker user info
  become: true
  ansible.builtin.user:
    name: "{{ docker_user }}"
  check_mode: true
  register: docker_user_info

- name: Example docker compose block
  become: true
  become_user: "{{ docker_user }}"
  environment:
    XDG_RUNTIME_DIR: /run/user/{{ docker_user_info.uid }}
    PATH: "{{ docker_user_info.home }}/bin:{{ ansible_env.PATH }}"
    DOCKER_HOST: "unix:///run/user/{{ docker_user_info.uid }}/docker.sock"
  block:
    - name: Install pip dependencies
      ansible.builtin.pip:
        name:
          - docker<7 # https://github.com/docker/docker-py/issues/3194
          - docker-compose

    - name: Create and start services
      community.docker.docker_compose:
        project_src: /var/tmp/
        files: "{{ docker_user }}-docker-compose.yml"
      register: compose_output

Testing with molecule

If Ansible Molecule with the vagrant plugin and related software is installed, running molecule test is supported.

tox -l will list all available tox test environments.

Contributing

Do you want to contribute? Great! Contributions are always youlcome, no matter how large or small. If you found something odd, feel free to submit a issue, improve the code by creating a pull request, or by sponsoring this project.

License

Apache License Version 2.0

Author Information

https://github.com/konstruktoid