Quick Start to Use xCAT Docker Image¶

A new Docker image will be published for each new release of xCAT. Use docker search xcat2 to list all Docker images xCAT has released. xCAT Docker image offical organization is xcat, repository is xcat2.

[dockerhost]# sudo docker search xcat2
NAME               DESCRIPTION                      STARS     OFFICIAL   AUTOMATED
xcat/xcat2            ...                            ...        ...          ...

The xCAT Docker images are tagged to match the xCAT releases, If you want to deploy the xCAT 2.14.6 version, pull down the xcat/xcat2:2.14.6 image. xCAT Docker image also has a latest tag to point to the latest release. Currently xCAT Docker images are based on CentOS.

Attention

To do discovery for POWER9 bare metal server, please refer to xCAT Genesis Base

Prerequisite for Docker Host¶

To run xCAT under Docker, the services SELinux and AppArmor on Docker host must be disabled.

SELinux can be disabled with:
```
echo 0 > /selinux/enforce
sed -i 's/^SELINUX=.*$/SELINUX=disabled/' /etc/selinux/config
```
AppArmor can be disabled with:
```
/etc/init.d/apparmor teardown
```
To run xCAT under Docker the ports described in document should be available.

For Linux user, use the following command to verify ports are not used
```
netstat -nlp |grep -E ":(3001|3002|68|53|873|80|69|12429|12430|67) "
```

Pull the xCAT Docker Image from DockerHub¶

To pull the latest xCAT Docker image, run

[dockerhost]# sudo docker pull xcat/xcat2:latest

Run xCAT in Docker Container¶

Run the xCAT Docker container with the Docker image xCAT/xCAT2:latest

[dockerhost]# sudo docker run -d \
     --name xcatmn  \
     --network=host  \
     --hostname xcatmn \
     --privileged   \
     -v /sys/fs/cgroup:/sys/fs/cgroup:ro  \
     -v /xcatdata:/xcatdata     \
     -v /var/log/xcat:/var/log/xcat  \
     -v /customer_data:/customer_data   \
     xcat/xcat2:latest

The descriptions:

–privileged=true:
name:	Assign a name to the container, this name can be used to manipulate the container on docker host.
–network=host:	Use the host network driver for a container, that container network stack is not isolated from the docker host.
hostname:	Specify the hostname of container, which is available inside the container.
	Give extended privileges to this container.
-v /sys/fs/cgroup:/sys/fs/cgroup:ro:
	Is mandatory configuration to enable systemd in container.
-v /xcatdata:/xcatdata:
	xCAT container will create `/xcatdata` volume to store configuration and OS distro data. I.e. xCAT important directories `/install`, `/tftpboot` and `/etc` will be saved under `/xcatdata`. If user does not explicitly mount this directory to docker host, this directory will be mounted under `/var/lib/docker/volumes/`.
-v /var/log/xcat:/var/log/xcat:
	All xCAT running logs are saved under `/var/log/xcat`. Use this setting to export them to Docker host.
-v /customer_data:/customer_data:
	Is optional. Use this setting to transfer user data between Docker host and container.

Run xCAT Command in Docker Container¶

To enter xCAT Docker container

[dockerhost]# sudo docker exec -it xcatmn bash
[xcatmn]#

Also can enter xCAT Docker container through ssh

[anynode]# ssh <docker_container_ip> -p 2200

Attention

Need to set site table depending on your own environment.

For example

[xcatmn]# chtab key=master site.value=<docker_host_ip>

Now container xcatmn will work as a normal xCAT management node, can run xCAT commands directly. For example

[xcatmn]# lsxcatd -a

Attention

Use of NFS outside of xCAT Docker container is recommended. For NFS service set up inside of xCAT Docker container, mount the shared directory with -v option when starting xCAT container.