When working in docker container, you need to start services differently. Let’s say you want to start mysql. You have 3 choices:

• mysqld_safe & which is a quick and dirty solution but its not idempotent.
• /etc/init.d/mysql restart its the old school way
• service mysql start that’s the new school way

Normally you would prefer the 3. option service mysql start but it needs upstart running which is normally the /sbin/init process with the special pid of 1.

Unfortunately inside of a docker instance the special 1 pid is rserved for the command started by docker. In most case its either /bin/bash, or sshd, ot whatever service you are running in the container.

when you try to start mysql with then you will most probably face the following message:

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 Failed to connect to socket /com/ubuntu/upstart: Connection refused

thats because upstart is not running, or phrasing differently: 1 pid is not /sbin/init

upstart workaround

There is a workaround for supressing this messages:

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dpkg-divert --local --rename --add /sbin/initctl
ln -s /bin/true /sbin/initctl

Of course you stil can’t use service mysql start, but at least you wont get those error messages.

related issues / pull-reqs

I can see that the docker issues/pull requests are disscussing it. But im still not sure the proper way to go. But here are the references:

• issue 223: the original Run /sbin/init issue
• issue 1024: the Container cannot connect to Upstart issue where i found the workaround
• issue 1311 : Production-ready process monitoring
• pull-req 898: Inject dockerinit at /.dockerinit instead of overwriting /sbin/init
• pull-req 1209: Upstart improvements
• pull-req 1883: /usr/sbin/policy-rc.d is added since the vast majority of docker users are surprised when they apt-get install or apt-get upgrade and services fail to start and that sometimes makes the install fail

update

I just read the docker integration into supervisor-s () is planned for the upcomming 0.7 version

For docker to be fully usable in production, it needs to cleanly integrate with the host machine’s process supervisor of choice. Whether it’s sysV-init, upstart, systemd, runit or supervisord, we want to make sure docker plays nice with your existing system. This will be a major focus of the 0.7 release.