This documentation is for the extended support release (ESR) version of Cumulus Linux. We will continue to keep this content up to date until 21 February, 2023, when ESR support ends. For more information about ESR, please read this knowledge base article.

If you are using the current version of Cumulus Linux, the content on this page may not be up to date. The current version of the documentation is available here. If you are redirected to the main page of the user guide, then this page may have been renamed; please search for it there.

Docker on Cumulus Linux

Cumulus Linux is based on Linux kernel 4.1, which supports the Docker engine. Docker can be installed directly on a Cumulus Linux switch, and Docker containers can be run natively on the switch. This section covers the installation and set up instructions for Docker.

Set up Docker on Cumulus Linux

Configure the Repositories

Add the following line to the end of /etc/apt/sources.list.d/jessie.list in a text editor, and save the file:

cumulus@switch:$ sudo nano /etc/apt/sources.list.d/jessie.list
     
...
     
deb http://httpredir.debian.org/debian jessie main contrib non-free
deb-src http://httpredir.debian.org/debian jessie main contrib non-free

Create the /etc/apt/sources.list.d/docker.list file, add the following line in a text editor, and save the file:

cumulus@switch:$ sudo nano /etc/apt/sources.list.d/docker.list
     
deb https://download.docker.com/linux/debian jessie stable

Install the Authentication Key

Install the authentication key for Docker:

    cumulus@switch:$ curl -fsSL https://download.docker.com/linux/debian/gpg | sudo apt-key add -

Verify that you now have the key with the fingerprint 9DC8 5822 9FC7 DD38 854A E2D8 8D81 803C 0EBF CD88, by searching for the last 8 characters of the fingerprint.

    cumulus@switch:$ sudo apt-key finger
    ...
    pub   4096R/0EBFCD88 2017-02-22
          Key fingerprint = 9DC8 5822 9FC7 DD38 854A  E2D8 8D81 803C 0EBF CD88
    uid                  Docker Release (CE deb) <docker@docker.com>
    sub   4096R/F273FCD8 2017-02-22

Install the docker-engine Package

Install Docker:

    cumulus@switch:$ sudo -E apt-get update -y
    cumulus@switch:$ sudo -E apt-get install docker-ce -qy

Configure systemd for Docker

Add docker as a new line at the bottom of /etc/vrf/systemd.conf, and save the file.
```
cumulus@switch:$ sudo nano /etc/vrf/systemd.conf
     
...
     
docker
```

Create the directory for the systemd configuration file for Docker:

cumulus@switch:$ sudo mkdir -p /etc/systemd/system/docker.service.d/

In a text editor, create a file called /etc/systemd/system/docker.service.d/noiptables-mgmt-vrf.conf, add the following lines to it, then save the file:

cumulus@switch:$ sudo nano /etc/systemd/system/docker.service.d/noiptables-mgmt-vrf.conf
     
[Service]
ExecStart=
ExecStart=/usr/bin/dockerd --iptables=false --ip-masq=false --ip-forward=false

In a text editor, edit a file called /lib/systemd/system/docker.service, and comment out the line starting with Delegate:
```
cumulus@switch:$ sudo nano /lib/systemd/system/docker.service
    
[Service]
...
#Delegate=yes
...
```
In a text editor, create a file called /etc/docker/daemon.json, add the following line to it, then save the file:
```
cumulus@switch:$ sudo nano /etc/docker/daemon.json

{"exec-opts": ["native.cgroupdriver=systemd"]}
```

Stop/Disable the Docker Services

Stop the various Docker services:

    cumulus@switch:$ sudo systemctl daemon-reload
    cumulus@switch:$ sudo systemctl stop docker.service docker.socket
    cumulus@switch:$ sudo systemctl disable docker.service docker.socket

Launch Docker and the Ubuntu Container

Enable the Docker management daemon so it starts when the switch boots:
```
cumulus@switch:$ sudo systemctl enable docker@mgmt
```

Start the Docker management daemon:

cumulus@switch:$ sudo systemctl start docker@mgmt

Run the Ubuntu container and launch the terminal instance:
```
cumulus@switch:$ docker run -i -t ubuntu /bin/bash
```

Performance Notes

Keep in mind switches are not servers, in terms of the hardware that drives them. As such, you should be mindful of the types of applications you want to run in containers on a Cumulus Linux switch. In general, depending upon the configuration of the container, you can expect DHCP servers, custom scripts and other lightweight services to run well. However, VPN, NAT and encryption-type services are CPU-intensive and could lead to undesirable effects on critical applications. Use of any resource-intensive services should be avoided and is not supported.