Why systemd is tricky in Docker

systemd is designed to be a system init manager for an entire operating system, and Docker containers are designed to run a single process. This mismatch makes running systemd inside Docker non-trivial. However, it is possible with some adjustments, and I will walk you through the process.

Prerequisites

• Ensure you have Docker installed on your machine.

• Familiarity with Docker commands.

Guide to Run systemd in an Ubuntu Docker Container

1. Create Dockerfile is required like below:

FROM ubuntu:22.04

RUN echo 'root:root' | chpasswd
RUN printf '#!/bin/sh\nexit 0' > /usr/sbin/policy-rc.d
RUN apt-get update
RUN apt-get install -y systemd systemd-sysv dbus dbus-user-session
RUN printf "systemctl start systemd-logind" >> /etc/profile

ENTRYPOINT ["/sbin/init"]
/sbin/init is important to init systemd and enable systemctl.

/sbin/init is important to init systemd and enable systemctl.

2. Then build the system.

docker build -t chinhnd/ubuntu-systemd -f Dockerfile .
docker run -it --privileged --cap-add=ALL chinhnd/ubuntu-systemd

Access the running container

Now that your container is running systemd, you can access it and use systemctl inside the container.

1. Enter the container:

    docker exec -it <container_id> bash
   

   Replace <container_id> with the actual container ID from the docker ps output.

   Then log in with root/root.

2. Check if systemd is running:

   Inside the container, run:

    systemctl
   

   If everything is set up correctly, you should see the output from systemctl showing the system services running.