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Update links and host integration documentation
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@ -14,12 +14,16 @@ Building a redis container to link as a child of our web application.
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Building the redis container
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----------------------------
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We will use a pre-build version of redis from the index under
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the name ``crosbymichael/redis``. If you are interested in the
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Dockerfile that was used to build this container here it is.
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Lets build a redis image with the following Dockerfile.
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.. code-block:: bash
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git clone https://github.com/antirez/redis.git
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cd redis
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git checkout 2.6
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# Save this Dockerfile to the root of the redis repository.
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# Build redis from source
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# Make sure you have the redis source code checked out in
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# the same directory as this Dockerfile
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@ -34,7 +38,6 @@ Dockerfile that was used to build this container here it is.
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ADD . /redis
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RUN (cd /redis && make)
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RUN (cd /redis && make test)
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RUN mkdir -p /redis-data
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VOLUME ["/redis-data"]
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@ -43,6 +46,9 @@ Dockerfile that was used to build this container here it is.
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ENTRYPOINT ["/redis/src/redis-server"]
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CMD ["--dir", "/redis-data"]
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# docker build our new redis image from source
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docker build -t redis-2.6 .
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We need to ``EXPOSE`` the default port of 6379 so that our link knows what ports
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to connect to our redis container on. If you do not expose any ports for the
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@ -54,31 +60,28 @@ Run the redis container
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.. code-block:: bash
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docker run -d -e PASSWORD=docker -name redis crosbymichael/redis --requirepass=docker
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docker run -d -e PASSWORD=docker -name redis redis-2.6 --requirepass docker
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This will run our redis container using the default port of 6379 and using docker
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as password to secure our service. By specifying the ``-name`` flag on run
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we will assign the name ``redis`` to this container.
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We can issue all the commands that you would expect; start, stop, attach, using the name.
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The name also allows us to link other containers into this one. If you do not specify a
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name on docker run, docker will automatically generate a name for your container.
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This will run our redis container wit the password docker
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to secure our service. By specifying the ``-name`` flag on run
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we will assign the name ``redis`` to this container. If we do not specify a name for
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our container via the ``-name`` flag docker will automatically generate a name for us.
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We can issue all the commands that you would expect; start, stop, attach, using the name for our container.
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The name also allows us to link other containers into this one.
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Linking redis as a child
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------------------------
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Next we can start a new web application that has a dependency on redis and apply a link
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to connect both containers. If you noticed when running our redis service we did not use
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the ``-p`` option to publish the redis port to the host system. Redis exposed port 6379
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but we did not publish the port. This allows docker to prevent all network traffic to
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the redis container except when explicitly specified within a link. This is a big win
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for security.
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to connect both containers. If you noticed when running our redis server we did not use
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the ``-p`` flag to publish the redis port to the host system. Redis exposed port 6379 via the Dockerfile
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and this is all we need to establish a link.
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Now lets start our web application with a link into redis.
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.. code-block:: bash
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docker run -t -i -link /redis:db -name webapp ubuntu bash
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docker run -t -i -link redis:db -name webapp ubuntu bash
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root@4c01db0b339c:/# env
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@ -101,22 +104,25 @@ Now lets start our web application with a link into redis.
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When we inspect the environment of the linked container we can see a few extra environment
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variables have been added. When you specified ``-link /redis:db`` you are telling docker
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to link the container named ``/redis`` into this new container with the alias ``db``.
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variables have been added. When you specified ``-link redis:db`` you are telling docker
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to link the container named ``redis`` into this new container with the alias ``db``.
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Environment variables are prefixed with the alias so that the parent container can access
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network and environment information from the child.
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network and environment information from the containers that are linked into it.
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.. code-block:: bash
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# The name of the child container
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DB_NAME=/webapp/db
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# The default protocol, ip, and port of the service running in the container
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DB_PORT=tcp://172.17.0.8:6379
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# A specific protocol, ip, and port of various services
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DB_PORT_6379_TCP=tcp://172.17.0.8:6379
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DB_PORT_6379_TCP_PROTO=tcp
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DB_PORT_6379_TCP_ADDR=172.17.0.8
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DB_PORT_6379_TCP_PORT=6379
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# Get environment variables of the container
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DB_ENV_PASSWORD=dockerpass
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@ -13,113 +13,47 @@ You can use your Docker containers with process managers like ``upstart``,
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Introduction
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------------
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If you want a process manager to manage your containers you will need to run
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the docker daemon with the ``-r=false`` so that docker will not automatically
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restart your containers when the host is restarted.
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When you have finished setting up your image and are happy with your
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running container, you may want to use a process manager to manage
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it. To help with this, we provide a simple image: ``creack/manager:min``
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it. When your run ``docker start -a`` docker will automatically attach
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to the process and forward all signals so that the process manager can
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detect when a container stops and correctly restart it.
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This image takes the container ID as parameter. We also can specify
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the kind of process manager and metadata like *Author* and
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*Description*. The output will will be text suitable for a
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configuration file, echoed to stdout. It is up to you to create the
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.conf file (for `upstart
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<http://upstart.ubuntu.com/cookbook/#job-configuration-file>`_) or
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.service file (for `systemd
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<http://0pointer.de/public/systemd-man/systemd.service.html>`_) and
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put it in the right place for your system.
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Here are a few sample scripts for systemd and upstart to integrate with docker.
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Usage
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-----
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Sample Upstart Script
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---------------------
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.. code-block:: bash
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docker run creack/manager:min [OPTIONS] <container id>
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description "Redis container"
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author "Me"
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start on filesystem and started lxc-net and started docker
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stop on runlevel [!2345]
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respawn
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exec docker start -a 0a7e070b698b
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.. program:: docker run creack/manager:min
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.. cmdoption:: -a="<none>"
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Author of the image
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.. cmdoption:: -d="<none>"
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Description of the image
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.. cmdoption:: -t="upstart"
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Type of manager requested: ``upstart`` or ``systemd``
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Example Output
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..............
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Sample systemd Script
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---------------------
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.. code-block:: bash
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docker run creack/manager:min -t="systemd" b28605f2f9a4
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[Unit]
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Description=<none>
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Author=<none>
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Description=Redis container
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Author=Me
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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 b28605f2f9a4
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ExecStop=/usr/bin/docker stop -t 2 b28605f2f9a4
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ExecStart=/usr/bin/docker start -a 0a7e070b698b
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ExecStop=/usr/bin/docker stop -t 2 0a7e070b698b
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[Install]
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WantedBy=local.target
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Development
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-----------
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The image ``creack/manager:min`` is a ``busybox`` base with the
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compiled binary of ``manager.go`` as the :ref:`Entrypoint
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<entrypoint_def>`. It is meant to be light and fast to download.
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If you would like to change or add things, you can download the full
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``creack/manager`` repository that contains ``creack/manager:min`` and
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``creack/manager:dev``.
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The Dockerfiles and the sources are available in
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`/contrib/host_integration
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<https://github.com/dotcloud/docker/tree/master/contrib/host_integration>`_.
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Upstart
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-------
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Upstart is the default process manager. The generated script will
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start the container after the ``docker`` daemon. If the container
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dies, it will respawn. Start/Restart/Stop/Reload are
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supported. Reload will send a SIGHUP to the container.
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Example (``upstart`` on Debian)
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...............................
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.. code-block:: bash
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CID=$(docker run -d creack/firefo-vnc)
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docker run creack/manager:min -a 'Guillaume J. Charmes <guillaume@dotcloud.com>' -d 'Awesome Firefox in VLC' $CID > /etc/init/firefoxvnc.conf
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You can now ``start firefoxvnc`` or ``stop firefoxvnc`` and if the container
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dies for some reason, upstart will restart it.
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Systemd
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-------
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In order to generate a systemd script, we need to use the ``-t``
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option. The generated script will start the container after docker
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daemon. If the container dies, it will respawn.
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``Start/Restart/Reload/Stop`` are supported.
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Example (``systemd`` on Fedora)
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...............................
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.. code-block:: bash
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CID=$(docker run -d creack/firefo-vnc)
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docker run creack/manager:min -t systemd -a 'Guillaume J. Charmes <guillaume@dotcloud.com>' -d 'Awesome Firefox in VLC' $CID > /usr/lib/systemd/system/firefoxvnc.service
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You can now run ``systemctl start firefoxvnc`` or ``systemctl stop
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firefoxvnc`` and if the container dies for some reason, ``systemd``
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will restart it.
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