Recently, I’ve been playing around with Fedora Atomic and Kubernetes. I ran into a frustrating problem in which I would attempt to start a service from within a script launched by cloud-init, only to have have systemctl block indefinitely because the service I was attempting to start was dependent on cloud-init finishing first.

It turns out that systemctl has a flag meant exactly for this situation:

       Do not synchronously wait for the requested operation to finish. If
       this is not specified, the job will be verified, enqueued and
       systemctl will wait until it is completed. By passing this
       argument, it is only verified and enqueued.

Replacing systemctl start <service> with systemctl start --no-block <service> has solved that particular problem.