EM: Add remain RemainAfterExit to metadata service

[surajssd]

This commit adds RemainAfterExit=true to metadata service. Other
services of type oneshot already have it.

Fixes: #1371

[invidian]

I wonder if we should have some test around this.

[surajssd]

I wonder if we should have some test around this.

Do you mean like a e2e? What ideas do you have? I am wondering how to create a erroneous condition?

[invidian]

Do you mean like a e2e? What ideas do you have? I am wondering how to create a erroneous condition?

We could at least test for systemctl show coreos-metadata | grep RemainAfterExit=yes, so if we refactor Terraform code (e.g. #449), we make sure all properties we need are in place.

If we want to test for side-effects, we would have to create a mock service, restart it and check if coreos-metadata run again, which would be better. We could also block coreos-metadata on IPtables level and ensure that it's restart does not block starting of dependant service.

On the other hand I'm not sure if it's worth the effort. We can implement grepping almost for free with existing tooling.

[iaguis]

My 2 cents. I would not add a test for this, I'd make sure with some script that all services have the right directives when refactoring.

[invidian]

My 2 cents. I would not add a test for this, I'd make sure with some script that all services have the right directives when refactoring.

That will be like milion tests to write before doing the actual refactoring. I'm 99% sure this is not going to happen 😄 But fair enough 👍

[surajssd]

Alright then merging it for now!