mirror of https://github.com/docker/docs.git
99 lines
3.3 KiB
Markdown
99 lines
3.3 KiB
Markdown
---
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description: How to generate scripts for upstart, systemd, etc.
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keywords: systemd, upstart, supervisor, docker, documentation, host integration
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redirect_from:
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- /engine/articles/host_integration/
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title: Start containers automatically
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---
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As of Docker 1.2, [restart
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policies](../reference/run.md#restart-policies-restart) are the built-in Docker
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mechanism for restarting containers when they exit. If set, restart policies
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will be used when the Docker daemon starts up, as typically happens after a
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system boot. Restart policies will ensure that linked containers are started in
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the correct order.
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If restart policies don't suit your needs (i.e., you have non-Docker processes
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that depend on Docker containers), you can use a process manager like
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[upstart](http://upstart.ubuntu.com/),
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[systemd](http://freedesktop.org/wiki/Software/systemd/) or
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[supervisor](http://supervisord.org/) instead.
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## Using a process manager
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Docker does not set any restart policies by default, but be aware that they will
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conflict with most process managers. So don't set restart policies if you are
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using a process manager.
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When you have finished setting up your image and are happy with your
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running container, you can then attach a process manager to manage it.
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When you run `docker start -a`, Docker will automatically attach to the
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running container, or start it if needed and forward all signals so that
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the process manager can detect when a container stops and correctly
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restart it.
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Here are a few sample scripts for systemd and upstart to integrate with
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Docker.
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## Examples
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The examples below show configuration files for two popular process managers,
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upstart and systemd. In these examples, we'll assume that we have already
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created a container to run Redis with `--name=redis_server`. These files define
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a new service that will be started after the docker daemon service has started.
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### upstart
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description "Redis container"
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author "Me"
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start on filesystem and started docker
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stop on runlevel [!2345]
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respawn
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script
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/usr/bin/docker start -a redis_server
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end script
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### systemd
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[Unit]
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Description=Redis container
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Requires=docker.service
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After=docker.service
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[Service]
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Restart=always
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ExecStart=/usr/bin/docker start -a redis_server
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ExecStop=/usr/bin/docker stop -t 2 redis_server
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[Install]
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WantedBy=default.target
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If you intend to use this as a system service, put the above contents in a file
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in the `/etc/systemd/system` directory, e.g.
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`/etc/systemd/system/docker-redis_server.service`.
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If you need to pass options to the redis container (such as `--env`),
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then you'll need to use `docker run` rather than `docker start`. This will
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create a new container every time the service is started, which will be stopped
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and removed when the service is stopped. Make sure you don't use "`-d`" for
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"detached mode". The command run from "`ExecStart`" needs to run in the foreground.
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[Service]
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...
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ExecStart=/usr/bin/docker run --env foo=bar --name redis_server redis
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ExecStop=/usr/bin/docker stop -t 2 redis_server
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ExecStopPost=/usr/bin/docker rm -f redis_server
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...
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To start using the service, reload systemd and start the service:
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systemctl daemon-reload
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systemctl start docker-redis_server.service
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To enable the service at system startup, execute:
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systemctl enable docker-redis_server.service
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