Running multiple Docker Daemons in the same machine

Forked from https://github.com/antIggl/multiple-docker-daemons (Big Thanks) with minor adjustments. This allows me to run additional docker containers on same device as a home assistant supervised install without Home Assistant flagging the install and unsupported (e.g. "System is unsupported because additional software outside the Home Assistant ecosystem has been detected").

I added a second containerd daemon for the second docker daemon, this prevents (probably harmless) cross talk between the docker daemons (i.e. requests to restart containers running on the alternative daemon).

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We separate the number of Docker daemons in the machine docker : the default installation docker-apps : the isolated docker installation for applications

Goal

The main goal is to have separate docker daemons running on the same machine isolated. Our use case was the jenkins server. I used to run my jenkins server in a docker container and I wanted to isolate the docker that uses jenkins to launch containers.

Procedure

First clone this repository and cd into it.

1. Create the service file for the daemon Edit appropriately docker-apps.service file and place it in /etc/systemd/system/ directory

sudo cp ./docker-apps.service /etc/systemd/system/docker-apps.service

2. Create the socket file

sudo cp ./docker-apps.socket /etc/systemd/system/docker-apps.socket

3. Create the new daemons data-root & run directories

sudo mkdir /var/lib/docker-apps /var/lib/containerd-dockers-apps /run/containerd-dockers-apps

4. Place the configuration file in /etc/docker/

Note: The bridge ip address (bip) is set to 172.25.0.1/16, different from Docker's default (172.17.0.1/16), to avoid ip conflicts

sudo cp ./docker-daemon-apps.json /etc/docker/docker-apps.json

5. Create service file for containerd daemon

sudo cp ./containerd-docker-apps.service /etc/systemd/system/containerd-docker-apps.service

6. Create containerd configuration file

sudo cp ./config-docker-apps.toml /etc/containerd/config-docker-apps.toml

7. Enable new services

sudo systemctl enable docker-apps.service
sudo systemctl enable docker-apps.socket
sudo systemctl enable containerd-docker-apps

8. Run new services

sudo systemctl start docker-apps.socket
sudo systemctl start docker-apps.service
sudo systemctl start containerd-docker-apps

9. Create alias so "docker-apps" can be used just as "docker" would

sudo echo alias docker-apps='docker -H unix:///var/run/docker-apps.sock' >> ~/.bashrc
source ~/.bashrc

Additional Notes

1)

I experienced issues with port mapping to containers on the second Docker daemon at system reboot which was only resolved by restarting the container. This seems to be an issue with the container starting before port mapping is set-up completely. I'm not sure if this is to do with the second daemon or not. It can be resolved by either setting up the container to run as a service with appropriate after conditions. Or adding a delay to the container starting via a Docker compose YAML file.

Contributors

• Antonios Inglezakis (@antIggl)