mirror of https://github.com/docker/docs.git
Misty Stanley-Jones
GitHub
parent
264274a842
commit
aa6dcc43bc
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@ -9,147 +9,62 @@ title: Control and configure Docker with systemd
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Many Linux distributions use systemd to start the Docker daemon. This document
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shows a few examples of how to customize Docker's settings.
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## Starting the Docker daemon
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## Start the Docker daemon
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### Start manually
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Once Docker is installed, you will need to start the Docker daemon.
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Most Linux distributions use `systemctl` to start services. If you
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do not have `systemctl`, use the `service` command.
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```bash
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$ sudo systemctl start docker
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# or on older distributions, you may need to use
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$ sudo service docker start
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```
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- **`systemctl`**:
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If you want Docker to start at boot, you should also:
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```bash
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$ sudo systemctl start docker
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```
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```bash
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$ sudo systemctl enable docker
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# or on older distributions, you may need to use
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$ sudo chkconfig docker on
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```
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- **`service`**:
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```bash
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$ sudo service docker start
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```
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### Start automatically at system boot
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If you want Docker to start at boot, see
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[Configure Docker to start on boot](/engine/installation/linux/linux-postinstall.md/#configure-docker-to-start-on-boot).
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## Custom Docker daemon options
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There are a number of ways to configure the daemon flags and environment variables
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for your Docker daemon.
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for your Docker daemon. The recommended way is to use the platform-independent
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`daemon.json` file, which is located in `/etc/docker/` on Linux by default. See
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[Daemon configuration file](/engine/reference/commandline/dockerd.md/#daemon-configuration-file).
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The recommended way is to use a systemd drop-in file (as described in the <a
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target="_blank"
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href="https://www.freedesktop.org/software/systemd/man/systemd.unit.html">systemd.unit</a>
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documentation). These are local files named `<something>.conf` in the
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`/etc/systemd/system/docker.service.d` directory.
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However, if you had previously used a package which had an `EnvironmentFile`
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(often pointing to `/etc/sysconfig/docker`) then for backwards compatibility,
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you drop a file with a `.conf` extension into the
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`/etc/systemd/system/docker.service.d` directory including the following:
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```conf
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[Service]
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EnvironmentFile=-/etc/sysconfig/docker
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EnvironmentFile=-/etc/sysconfig/docker-storage
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EnvironmentFile=-/etc/sysconfig/docker-network
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ExecStart=
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ExecStart=/usr/bin/dockerd $OPTIONS \
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$DOCKER_STORAGE_OPTIONS \
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$DOCKER_NETWORK_OPTIONS \
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$BLOCK_REGISTRY \
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$INSECURE_REGISTRY
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```
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To check if the `docker.service` uses an `EnvironmentFile`:
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```bash
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$ systemctl show docker | grep EnvironmentFile
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EnvironmentFile=-/etc/sysconfig/docker (ignore_errors=yes)
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```
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Alternatively, find out where the service file is located:
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```bash
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$ systemctl show --property=FragmentPath docker
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FragmentPath=/usr/lib/systemd/system/docker.service
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$ grep EnvironmentFile /usr/lib/systemd/system/docker.service
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EnvironmentFile=-/etc/sysconfig/docker
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```
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You can customize the Docker daemon options using override files as explained in
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the [HTTP Proxy example](systemd.md#http-proxy) below. The files located in
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`/usr/lib/systemd/system` or `/lib/systemd/system` contain the default options
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and should not be edited.
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You can configure nearly all daemon configuration options using `daemon.json`. The following
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example configures two options. One thing you cannot configure using `daemon.json` mechanism is
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a [HTTP proxy](#http-proxy).
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### Runtime directory and storage driver
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You may want to control the disk space used for Docker images, containers
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and volumes by moving it to a separate partition.
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In this example, we'll assume that your `docker.service` file looks something
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like:
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To accomplish this, set the following flags in the `daemon.json` file:
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```conf
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[Unit]
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Description=Docker Application Container Engine
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Documentation=https://docs.docker.com
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After=network.target
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[Service]
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Type=notify
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# the default is not to use systemd for cgroups because the delegate issues still
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# exists and systemd currently does not support the cgroup feature set required
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# for containers run by docker
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ExecStart=/usr/bin/dockerd
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ExecReload=/bin/kill -s HUP $MAINPID
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# Having non-zero Limit*s causes performance problems due to accounting overhead
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# in the kernel. We recommend using cgroups to do container-local accounting.
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LimitNOFILE=infinity
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LimitNPROC=infinity
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LimitCORE=infinity
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# Uncomment TasksMax if your systemd version supports it.
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# Only systemd 226 and above support this version.
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#TasksMax=infinity
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TimeoutStartSec=0
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# set delegate yes so that systemd does not reset the cgroups of docker containers
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Delegate=yes
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# kill only the docker process, not all processes in the cgroup
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KillMode=process
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[Install]
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WantedBy=multi-user.target
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```
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This will allow us to add extra flags via a drop-in file (mentioned above) by
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placing a file containing the following in the `/etc/systemd/system/docker.service.d`
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directory:
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```conf
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[Service]
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ExecStart=
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ExecStart=/usr/bin/dockerd --graph=/mnt/docker-data --storage-driver=overlay
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```
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You can also set other environment variables in this file, for example, the
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`HTTP_PROXY` environment variables described below.
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To modify the ExecStart configuration, specify an empty configuration followed
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by a new configuration as follows:
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```conf
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[Service]
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ExecStart=
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ExecStart=/usr/bin/dockerd --bip=172.17.42.1/16
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```
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If you fail to specify an empty configuration, Docker reports an error such as:
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```conf
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docker.service has more than one ExecStart= setting, which is only allowed for Type=oneshot services. Refusing.
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```none
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{
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"graph": "/mnt/docker-data",
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"storage-drivers": "overlay"
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}
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```
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### HTTP proxy
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The Docker daemon uses the `HTTP_PROXY` and `NO_PROXY` environmental variables in
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its start-up environment to configure HTTP proxy behavior. You cannot configure
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these environment variables using the `daemon.json` file.
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This example overrides the default `docker.service` file.
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If you are behind an HTTP proxy server, for example in corporate settings,
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@ -197,7 +112,7 @@ you will need to add this configuration in the Docker systemd service file.
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## Manually creating the systemd unit files
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When installing the binary without a package, you may want
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to integrate Docker with systemd. For this, simply install the two unit files
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(service and socket) from [the github
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to integrate Docker with systemd. For this, install the two unit files
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(`service` and `socket`) from [the github
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repository](https://github.com/docker/docker/tree/master/contrib/init/systemd)
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to `/etc/systemd/system`.
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