Tukukkk

I know Systemd is not recommended on Docker containers but is it possible?

I have staging/prod environments on Ubuntu 18.04 cloud VMs deployed with Ansible;

My current dev environment is a Ubuntu 18.04 Vagrantfile that uses the same Ansible playbook.yml of staging/prod

Now I'm trying to replace the Vagrantfile with a Dockerfile for development but the Ansible playbook.yml fails when applying systemd modules. I would like to have systemd on my dev environment as well so that I can test changes on my playbook.yml local. Any idea how I can do it?

If I try to build with Dockerfile and playbook.yml as below, I get an error Failed to find required executable systemctl in paths.

If I add RUN apt-get install systemd to Dockerfile nd try to build, I get an error System has not been booted with systemd as init system

Sample Dockerfile:

FROM ubuntu:18.04



ADD . /app

WORKDIR /app



# Install Python3 pip used to install Ansible

RUN apt-get update && apt-get install -y 

  python3-pip 



# Install Ansible

RUN pip3 install --trusted-host pypi.python.org ansible

RUN ansible-playbook playbook.yml -i inventory



EXPOSE 80

Sample playbook.yml:

---

- name: Ansible playbook to setup dev environment 

  hosts: all

  vars:

    ansible_python_interpreter: "/usr/bin/python3"

    debug: True

  become: yes

  become_method: sudo

  tasks:

    - name: Copy App Gunicorn systemd config

      template:

        src: app_gunicorn.service

        dest: /etc/systemd/system/



    - name: Enable App Gunicorn on systemd

      systemd: state=started name=app_gunicorn

Sample inventory:

docker-dev ansible_host=localhost ansible_connection=local

That's a perfect example where the docker-systemctl-replacement script should be used.

It has been developed to allow ansible scripts to target both virtual machines and docker containers. You do not need to enable a real systemd, just overwrite /usr/bin/systemctl in operating systems that are otherwise under systemd control. The docker container will then look good enough for ansible, whereas I am more used to use the general 'service:' module instead of the specific 'systemd:' module.