Scheduling job with a dependency on another job

[jason-riddle]

Is it possible to schedule a job only after another job is successful scheduled? A use case for example, would be to use one docker container to provide a REST API (https://github.com/begriffs/postgrest) for another docker container (postgres), but the REST API docker container should only come up once the database container is up and passed it's health check.

[dadgar]

Hey! Nomad currently does not have a way to express job dependencies but it is something on our roadmap. From your description it sounds like you need dependencies between tasks/task groups not jobs. A job would only be finished once all the task groups are dead. If you look at issue #419 I think it captures this issue, so I am going to mark as closed.

[zapman449]

I believe this should be re-opened.

Here's a use-case: I want to run hashicorp vault and docker-registry from within nomad. The other containers will need these to be available before they can start, but #419 argues for pushing all my apps into a single job.

Granted, this is less obvious for vault, but our private registry is foundational for everything.

[suslovsergey]

Any news?

[aaronhurt]

Similar use case here. We would like to be sure that things like our OAuth service, auditing service, etc.. are started and listed as dependencies before other backend applications start.

[DhashS]

Different use case here!

I'd like to have some control around precendence order in which my networking, services, and templates fire off. The suggestion of job-dependencies is limiting, unless there's some funky n-pass evaluation stuff, and execution in the same container.

My use case provisions container environment variables and config files based on the services running and registered with consul. Without a strict happens-before ordering, i get a non-deterministic template.

[scalp42]

See #419 for the same kind of issue.

[pznamensky]

It's quite obvious feature for the orchestrator, and at the moment, it's one of the most desired functionality for us.
I still hope it would be implemented in Nomad.

[116davinder]

I believe, dependencies can be defined like this in nomad job spec.

# job spec example
dependency 1 {
  provider = consul/nomad/etc.
  check = wait for consul/nomad service / nomad-status to become health
    pattern = nomad/job/group/task [ if nomad service, here i want to see, if nomad can check if nomad service is up or not]
    pattern = name-of-consul-service [ if consul service, here i want to see, if nomad can check if consul service is up or not ]
    pattern = nomad/job/group/task-name [ if nomad-status, here, I want to see, what nomad know about the task, whether its up or not]

  interval = 10s
  retry = 100
  delay = 15s
}
dependency 2 {
  provider = consul/nomad/etc.
  check = wait for consul/nomad service / nomad-status to become health
    pattern = nomad/job/group/task [ if nomad service, here i want to see, if nomad can check if nomad service is up or not]
    pattern = name-of-consul-service [ if consul service, here i want to see, if nomad can check if consul service is up or not ]
    pattern = nomad/job/group/task-name [ if nomad-status, here, I want to see, what nomad know about the task/group/job, whether its up or not]

  interval = 10s
  retry = 100
  delay = 15s
}

[richard-tns]

I believe, dependencies can be defined like this in nomad job spec.

# job spec example
dependency 1 {
  provider = consul/nomad/etc.
  check = wait for consul/nomad service / nomad-status to become health
    pattern = nomad/job/group/task [ if nomad service, here i want to see, if nomad can check if nomad service is up or not]
    pattern = name-of-consul-service [ if consul service, here i want to see, if nomad can check if consul service is up or not ]
    pattern = nomad/job/group/task-name [ if nomad-status, here, I want to see, what nomad know about the task, whether its up or not]

  interval = 10s
  retry = 100
  delay = 15s
}
dependency 2 {
  provider = consul/nomad/etc.
  check = wait for consul/nomad service / nomad-status to become health
    pattern = nomad/job/group/task [ if nomad service, here i want to see, if nomad can check if nomad service is up or not]
    pattern = name-of-consul-service [ if consul service, here i want to see, if nomad can check if consul service is up or not ]
    pattern = nomad/job/group/task-name [ if nomad-status, here, I want to see, what nomad know about the task/group/job, whether its up or not]

  interval = 10s
  retry = 100
  delay = 15s
}

This is incorrect and is just the proposal in #19291

There is still no method to schedule dependencies between jobs

[DhashS]

I ended up using terraform for this. nomad_job and consul_health_check’s work together as a pair to make a job node that can be depended on for separate dependency nodes