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<!-- [metadata]>
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title = "Configuring and running Docker"
description = "Configuring and running the Docker daemon on various distributions"
keywords = ["docker, daemon, configuration, running, process managers"]
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parent = "smn_administrate"
weight = 3
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<![end-metadata]-->
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# Configuring and running Docker on various distributions
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After successfully installing Docker, the `docker` daemon runs with its default
configuration.
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In a production environment, system administrators typically configure the
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`docker` daemon to start and stop according to an organization's requirements. In most
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cases, the system administrator configures a process manager such as `SysVinit` , `Upstart` ,
or `systemd` to manage the `docker` daemon's start and stop.
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### Running the docker daemon directly
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The `docker` daemon can be run directly using the `docker daemon` command. By default it listens on
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the Unix socket `unix:///var/run/docker.sock`
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$ docker daemon
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INFO[0000] +job init_networkdriver()
INFO[0000] +job serveapi(unix:///var/run/docker.sock)
INFO[0000] Listening for HTTP on unix (/var/run/docker.sock)
...
...
### Configuring the docker daemon directly
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If you're running the `docker` daemon directly by running `docker daemon` instead
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of using a process manager, you can append the configuration options to the `docker` run
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command directly. Other options can be passed to the `docker` daemon to configure it.
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Some of the daemon's options are:
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| Flag | Description |
|-----------------------|-----------------------------------------------------------|
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| `-D` , `--debug=false` | Enable or disable debug mode. By default, this is false. |
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| `-H` ,`--host=[]` | Daemon socket(s) to connect to. |
| `--tls=false` | Enable or disable TLS. By default, this is false. |
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Here is a an example of running the `docker` daemon with configuration options:
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$ docker daemon -D --tls=true --tlscert=/var/docker/server.pem --tlskey=/var/docker/serverkey.pem -H tcp://192.168.59.3:2376
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These options :
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- Enable `-D` (debug) mode
- Set `tls` to true with the server certificate and key specified using `--tlscert` and `--tlskey` respectively
- Listen for connections on `tcp://192.168.59.3:2376`
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The command line reference has the [complete list of daemon flags ](../reference/commandline/daemon.md )
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with explanations.
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## Ubuntu
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As of `14.04` , Ubuntu uses Upstart as a process manager. By default, Upstart jobs
are located in `/etc/init` and the `docker` Upstart job can be found at `/etc/init/docker.conf` .
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After successfully [installing Docker for Ubuntu ](../installation/ubuntulinux.md ),
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you can check the running status using Upstart in this way:
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$ sudo status docker
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docker start/running, process 989
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### Running Docker
You can start/stop/restart the `docker` daemon using
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$ sudo start docker
$ sudo stop docker
$ sudo restart docker
### Configuring Docker
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You configure the `docker` daemon in the `/etc/default/docker` file on your
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system. You do this by specifying values in a `DOCKER_OPTS` variable.
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To configure Docker options:
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1. Log into your host as a user with `sudo` or `root` privileges.
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2. If you don't have one, create the `/etc/default/docker` file on your host. Depending on how
you installed Docker, you may already have this file.
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3. Open the file with your favorite editor.
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```
$ sudo vi /etc/default/docker
```
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4. Add a `DOCKER_OPTS` variable with the following options. These options are appended to the
`docker` daemon's run command.
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```
DOCKER_OPTS="-D --tls=true --tlscert=/var/docker/server.pem --tlskey=/var/docker/serverkey.pem -H tcp://192.168.59.3:2376"
```
These options :
- Enable `-D` (debug) mode
- Set `tls` to true with the server certificate and key specified using `--tlscert` and `--tlskey` respectively
- Listen for connections on `tcp://192.168.59.3:2376`
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The command line reference has the [complete list of daemon flags ](../reference/commandline/daemon.md )
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with explanations.
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5. Save and close the file.
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6. Restart the `docker` daemon.
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```
$ sudo restart docker
```
7. Verify that the `docker` daemon is running as specified with the `ps` command.
```
$ ps aux | grep docker | grep -v grep
```
### Logs
By default logs for Upstart jobs are located in `/var/log/upstart` and the logs for `docker` daemon
can be located at `/var/log/upstart/docker.log`
$ tail -f /var/log/upstart/docker.log
INFO[0000] Loading containers: done.
INFO[0000] docker daemon: 1.6.0 4749651; execdriver: native-0.2; graphdriver: aufs
INFO[0000] +job acceptconnections()
INFO[0000] -job acceptconnections() = OK (0)
INFO[0000] Daemon has completed initialization
## CentOS / Red Hat Enterprise Linux / Fedora
As of `7.x` , CentOS and RHEL use `systemd` as the process manager. As of `21` , Fedora uses
`systemd` as its process manager.
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After successfully installing Docker for [CentOS ](../installation/centos.md )/[Red Hat Enterprise Linux](../installation/rhel.md)/[Fedora](../installation/fedora.md), you can check the running status in this way:
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$ sudo systemctl status docker
### Running Docker
You can start/stop/restart the `docker` daemon using
$ sudo systemctl start docker
$ sudo systemctl stop docker
$ sudo systemctl restart docker
If you want Docker to start at boot, you should also:
$ sudo systemctl enable docker
### Configuring Docker
You configure the `docker` daemon in the `/etc/sysconfig/docker` file on your
host. You do this by specifying values in a variable. For CentOS 7.x and RHEL 7.x, the name
of the variable is `OPTIONS` and for CentOS 6.x and RHEL 6.x, the name of the variable is
`other_args` . For this section, we will use CentOS 7.x as an example to configure the `docker`
daemon.
By default, systemd services are located either in `/etc/systemd/service` , `/lib/systemd/system`
or `/usr/lib/systemd/system` . The `docker.service` file can be found in either of these three
directories depending on your host.
To configure Docker options:
1. Log into your host as a user with `sudo` or `root` privileges.
2. If you don't have one, create the `/etc/sysconfig/docker` file on your host. Depending on how
you installed Docker, you may already have this file.
3. Open the file with your favorite editor.
```
$ sudo vi /etc/sysconfig/docker
```
4. Add a `OPTIONS` variable with the following options. These options are appended to the
command that starts the `docker` daemon.
```
OPTIONS="-D --tls=true --tlscert=/var/docker/server.pem --tlskey=/var/docker/serverkey.pem -H tcp://192.168.59.3:2376"
```
These options :
- Enable `-D` (debug) mode
- Set `tls` to true with the server certificate and key specified using `--tlscert` and `--tlskey` respectively
- Listen for connections on `tcp://192.168.59.3:2376`
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The command line reference has the [complete list of daemon flags ](../reference/commandline/daemon.md )
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with explanations.
5. Save and close the file.
6. Restart the `docker` daemon.
```
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$ sudo systemctl restart docker
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```
7. Verify that the `docker` daemon is running as specified with the `ps` command.
```
$ ps aux | grep docker | grep -v grep
```
### Logs
systemd has its own logging system called the journal. The logs for the `docker` daemon can
be viewed using `journalctl -u docker`
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$ sudo journalctl -u docker
May 06 00:22:05 localhost.localdomain systemd[1]: Starting Docker Application Container Engine...
May 06 00:22:05 localhost.localdomain docker[2495]: time="2015-05-06T00:22:05Z" level="info" msg="+job serveapi(unix:///var/run/docker.sock)"
May 06 00:22:05 localhost.localdomain docker[2495]: time="2015-05-06T00:22:05Z" level="info" msg="Listening for HTTP on unix (/var/run/docker.sock)"
May 06 00:22:06 localhost.localdomain docker[2495]: time="2015-05-06T00:22:06Z" level="info" msg="+job init_networkdriver()"
May 06 00:22:06 localhost.localdomain docker[2495]: time="2015-05-06T00:22:06Z" level="info" msg="-job init_networkdriver() = OK (0)"
May 06 00:22:06 localhost.localdomain docker[2495]: time="2015-05-06T00:22:06Z" level="info" msg="Loading containers: start."
May 06 00:22:06 localhost.localdomain docker[2495]: time="2015-05-06T00:22:06Z" level="info" msg="Loading containers: done."
May 06 00:22:06 localhost.localdomain docker[2495]: time="2015-05-06T00:22:06Z" level="info" msg="docker daemon: 1.5.0-dev fc0329b/1.5.0; execdriver: native-0.2; graphdriver: devicemapper"
May 06 00:22:06 localhost.localdomain docker[2495]: time="2015-05-06T00:22:06Z" level="info" msg="+job acceptconnections()"
May 06 00:22:06 localhost.localdomain docker[2495]: time="2015-05-06T00:22:06Z" level="info" msg="-job acceptconnections() = OK (0)"
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_Note: Using and configuring journal is an advanced topic and is beyond the scope of this article._