Run level scripts on rancherOS

Archive RancherOS
1

Hi Ranchers,

Not sure if this is in the documentation, but for others…

/opt/rancher/bin/start.sh <- runs before docker has started
/etc/rc.local <- runs after docker has started - although scripts needs to check docker has finished loading (e.g. check for docker info) if you are requiring use of docker.

My question to the Rancher team is:

Is it possible to set up scripts that can run on termination or reboot of rancherOS?

Thanks.

2

If we were to do that it would be with the following caveats.

  1. It would be unreliable, because things crash :slightly_smiling:
  2. It would have to complete in less than 10 seconds.
3

Ok so currently no. My use case is running rancher with spotinst. When the host gets a shutdown signal, any other os I could put a script in to ping my hip chat. I know rancheros is minimal but might be nice to support some shutdown hook?

4

You can actually do this today in a way. Create a container that does nothing but wait for SIGTERM. After SIGTERM ping hip chat. On shutdown of rancher os we do stop all system services (must be in system-docker, not user-docker). So your container would shutdown.

5

@richardoflynn For example the following script will print “I’m melting” on shutdown. You just have to launch it with -i or stdin_open: true

#!/bin/bash

die()
{
    echo "I'm melting"
    exit 0
}

trap die TERM

read I_FEEL_LIKE_I_SERVE_NO_PURPOSE
6

Hi @ibuildthecloud,

I need a way to set some aliases and custom configuration to RancherOS / console. Could you provide such a example executed during boot?

I created a system-docker convoy os-service for example, but need an alias for console usage (convoy binary can’t be bind to the console, so I have to use docker exec …).
91dbadb6ddd4 pwfoo/private:os-convoy-vfs "/convoy-start.sh" 3 days ago Up 9 minutes os_convoy-vfs_1

So something like a config container ( need to know how the convoy container is named) or a /etc/rc.local is needed.
alias sysdocker="sudo system-docker"
alias convoy="sudo system-docker exec -ti os_convoy-vfs_1 convoy"

7

@pwFoo Adding the aliases to a script in /etc/profile.d should do the trick

#cloud-config
write_files:
  - path: /etc/profile.d/alias.sh
    permissions: "0755"
    owner: root
    content: |
      alias convoy="sudo system-docker exec -it convoy convoy"
      alias serf="sudo system-docker exec -it serf serf"
      alias sd="sudo system-docker"