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Fixing the links Updating with Seb's comments Adding weight Fixing the engine aliases Updating after Arun pushed Removing empty file Signed-off-by: Mary Anthony <mary@docker.com>
119 lines
4.1 KiB
Markdown
119 lines
4.1 KiB
Markdown
<!--[metadata]>
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+++
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aliases = ["/engine/articles/using_supervisord/"]
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title = "Using Supervisor with Docker"
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description = "How to use Supervisor process management with Docker"
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keywords = ["docker, supervisor, process management"]
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[menu.main]
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parent = "engine_admin"
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+++
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<![end-metadata]-->
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# Using Supervisor with Docker
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> **Note**:
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> - **If you don't like sudo** then see [*Giving non-root
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> access*](../installation/binaries.md#giving-non-root-access)
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Traditionally a Docker container runs a single process when it is
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launched, for example an Apache daemon or a SSH server daemon. Often
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though you want to run more than one process in a container. There are a
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number of ways you can achieve this ranging from using a simple Bash
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script as the value of your container's `CMD` instruction to installing
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a process management tool.
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In this example we're going to make use of the process management tool,
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[Supervisor](http://supervisord.org/), to manage multiple processes in
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our container. Using Supervisor allows us to better control, manage, and
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restart the processes we want to run. To demonstrate this we're going to
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install and manage both an SSH daemon and an Apache daemon.
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## Creating a Dockerfile
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Let's start by creating a basic `Dockerfile` for our
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new image.
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FROM ubuntu:13.04
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MAINTAINER examples@docker.com
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## Installing Supervisor
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We can now install our SSH and Apache daemons as well as Supervisor in
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our container.
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RUN apt-get update && apt-get install -y openssh-server apache2 supervisor
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RUN mkdir -p /var/lock/apache2 /var/run/apache2 /var/run/sshd /var/log/supervisor
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Here we're installing the `openssh-server`,
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`apache2` and `supervisor`
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(which provides the Supervisor daemon) packages. We're also creating four
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new directories that are needed to run our SSH daemon and Supervisor.
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## Adding Supervisor's configuration file
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Now let's add a configuration file for Supervisor. The default file is
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called `supervisord.conf` and is located in
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`/etc/supervisor/conf.d/`.
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COPY supervisord.conf /etc/supervisor/conf.d/supervisord.conf
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Let's see what is inside our `supervisord.conf`
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file.
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[supervisord]
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nodaemon=true
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[program:sshd]
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command=/usr/sbin/sshd -D
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[program:apache2]
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command=/bin/bash -c "source /etc/apache2/envvars && exec /usr/sbin/apache2 -DFOREGROUND"
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The `supervisord.conf` configuration file contains
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directives that configure Supervisor and the processes it manages. The
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first block `[supervisord]` provides configuration
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for Supervisor itself. We're using one directive, `nodaemon`
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which tells Supervisor to run interactively rather than
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daemonize.
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The next two blocks manage the services we wish to control. Each block
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controls a separate process. The blocks contain a single directive,
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`command`, which specifies what command to run to
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start each process.
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## Exposing ports and running Supervisor
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Now let's finish our `Dockerfile` by exposing some
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required ports and specifying the `CMD` instruction
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to start Supervisor when our container launches.
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EXPOSE 22 80
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CMD ["/usr/bin/supervisord"]
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Here We've exposed ports 22 and 80 on the container and we're running
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the `/usr/bin/supervisord` binary when the container
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launches.
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## Building our image
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We can now build our new image.
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$ docker build -t <yourname>/supervisord .
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## Running our Supervisor container
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Once We've got a built image we can launch a container from it.
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$ docker run -p 22 -p 80 -t -i <yourname>/supervisord
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2013-11-25 18:53:22,312 CRIT Supervisor running as root (no user in config file)
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2013-11-25 18:53:22,312 WARN Included extra file "/etc/supervisor/conf.d/supervisord.conf" during parsing
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2013-11-25 18:53:22,342 INFO supervisord started with pid 1
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2013-11-25 18:53:23,346 INFO spawned: 'sshd' with pid 6
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2013-11-25 18:53:23,349 INFO spawned: 'apache2' with pid 7
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. . .
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We've launched a new container interactively using the `docker run` command.
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That container has run Supervisor and launched the SSH and Apache daemons with
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it. We've specified the `-p` flag to expose ports 22 and 80. From here we can
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now identify the exposed ports and connect to one or both of the SSH and Apache
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daemons.
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