How can you run more than one simultaneous job in Ansible Tower?

Question

It seems that all jobs are enqueued, and only one will run at a time. How can we run more than one?

Answer 1

Tower is designed to parallelize jobs, but there are a couple of cases where it will not.

1. If you have your inventory or SCM set up to "update on launch" with no cache or the cahche has expired, then any additional jobs will be stuck pending behind the inventory or SCM update. The inventory and SCM will not update until after the currently running job is done.
2. If you are trying to run multiple jobs against the same host: Tower will not run multiple jobs against the same host at the same time in order to avoid race conditions. (localhost is a possible exception). If you need multiple jobs to run against the same host at the same time then you need to create two inventories and put that host in both inventories, running the two jobs against different inventories. In this situation, Tower does not know that you are running against the same host.

Answer 2

Simultaneous jobs can be executed from Tower. Job templates have "Enable Concurrent Jobs" option. See section "15.4. Job Concurrency" at http://docs.ansible.com/ansible-tower/latest/html/userguide/jobs.html.