Docker container exiting when launched with Fleet

Question

I am launching a Docker container on CoreOS using Fleet via the following system file:

[Unit]
Description=Developer News API
After=docker.service
Requires=docker.service

[Service]
ExecStartPre=-/usr/bin/docker kill devnews-core
ExecStartPre=-/usr/bin/docker rm devnews-core
ExecStartPre=/usr/bin/docker pull imjacobclark/devnews-core
ExecStart=/usr/bin/docker run -d -p 1337:1337 --name devnews-core imjacobclark/devnews-core
ExecStop=/usr/bin/docker stop devnews-core
TimeoutStartSec=0
Restart=always
RestartSec=10s

The main Docker command I am executing here is docker run -d -p 1337:1337 --name devnews-core imjacobclark/devnews-core which when executed standalone works correctly and has the desired outcome of a web service being exposed on port 1337.

However, when I execute fleetctl devnews-core.service , Fleet states the launch is done, however keeps repeating the launch, this is because upon npm install within the container, Docker exits.

Starting the service via Fleet:

core@coreos01 ~/devnews-coreos/fleet $ fleetctl start devnews-core.service 
Unit devnews-core.service launched on 8fdc9312.../

Logs:

core@coreos01 ~/devnews-coreos/fleet $ fleetctl --tunnel journal devnews-core.service 
-- Logs begin at Wed 2015-02-25 13:41:25 UTC, end at Wed 2015-02-25 23:08:55 UTC. --
Feb 25 23:08:47 coreos03 docker[6404]: 44d8123e3829: Download complete
Feb 25 23:08:47 coreos03 docker[6404]: 1e278393641a: Download complete
Feb 25 23:08:47 coreos03 docker[6404]: ec0fa4f2b126: Download complete
Feb 25 23:08:47 coreos03 docker[6404]: 0d98c76d34ce: Download complete
Feb 25 23:08:47 coreos03 docker[6404]: eb0a99f0e308: Download complete
Feb 25 23:08:47 coreos03 docker[6404]: eb0a99f0e308: Download complete
Feb 25 23:08:47 coreos03 docker[6404]: Status: Image is up to date for imjacobclark/devnews-core:latest
Feb 25 23:08:47 coreos03 systemd[1]: Started Developer News API.
Feb 25 23:08:47 coreos03 docker[6414]: 1d90cf825518610cbd15a44873c1e2640d40522632ed5417ac91f22b82c20ac4
Feb 25 23:08:47 coreos03 docker[6456]: devnews-core

The node stating Docker has failed:

core@coreos03 ~ $ docker ps -l
CONTAINER ID        IMAGE                              COMMAND             CREATED             STATUS                       PORTS               NAMES
a5970b9f6819        imjacobclark/devnews-core:latest   "npm start"         6 seconds ago       Exited (143) 5 seconds ago                       devnews-core

This container is simply built of the standard Docker Node.js container from the public DockerHub registry and is committed after I have built my app into the container.

Am I missing anything vital from my service file to cause Fleet to not launch the container correctly?

Answer 1

The answer was simple, don't start Docker in demonised mode, the correct system file should be as follows:

[Unit]
Description=Developer News API
After=docker.service
Requires=docker.service

[Service]
ExecStartPre=-/usr/bin/docker kill devnews-core
ExecStartPre=-/usr/bin/docker rm devnews-core
ExecStartPre=/usr/bin/docker pull imjacobclark/devnews-core
ExecStart=/usr/bin/docker run -p 1337:1337 --name devnews-core imjacobclark/devnews-core
ExecStop=/usr/bin/docker stop devnews-core
TimeoutStartSec=0
Restart=always
RestartSec=10s

Essentially, the Docker run command should be as follows:

docker run -p 1337:1337 --name devnews-core imjacobclark/devnews-core