You can automate running commands on boot using the runcmd
cloud-config directive. Commands can be specified as either a list or a string. In the latter case, the command is executed with sh
.
#cloud-config
runcmd:
- [ touch, /home/rancher/test1 ]
- echo "test" > /home/rancher/test2
Commands specified using runcmd
will be executed within the context of the console
container. More details on the ordering of commands run in the console
container can be found here.
When using runcmd
, RancherOS will wait for all commands to complete before starting Docker. As a result, any docker run
command should not be placed under runcmd
. Instead, the /etc/rc.local
script can be used. RancherOS will not wait for commands in this script to complete, so you can use the wait-for-docker
command to ensure that the Docker daemon is running before performing any docker run
commands.
#cloud-config
rancher:
write_files:
- path: /etc/rc.local
permissions: "0755"
owner: root
content: |
#!/bin/bash
wait-for-docker
docker run -d nginx
Running Docker commands in this manner is useful when pieces of the docker run
command are dynamically generated. For services whose configuration is static, adding a system service is recommended.
The bootcmd
parameter can be used to run commands earlier in the boot process. In particular, bootcmd
will be executed while RancherOS is still running from memory and before System Docker and any system services are started.
The syntax for bootcmd is the same as runcmd
.
#cloud-config
bootcmd:
- [ mdadm, --assemble, --scan ]