[feat] Add a new prepare_cmds partition configuration parameter which allows to emit commands before loading any environment

[rsarm]

Closes #1734

[teojgo]

We wil also need a unittest for this.

[vkarak]

I don't think this PR is correct in its principle. These commands are partition specific and not test-specific. I don't think we should anything to the test API. Instead, these commands must be part of the configuration of the partition. This is what I understand from the issue: every script submitted to that partition needs to have a module purge.

[vkarak]

The implementation looks good. I have a suggestion about the name of the option and we still need the following:

1. A unit test or adapt test_prepare
2. Documentation (both in the configuration reference and here (we need to update the script template).

[teojgo]

@rsarm, @vkarak do you think that this is the case for both build/run scripts? I have the feeling that this is needed only for the compute nodes, at least on #1734

[vkarak]

@teojgo I think you are correct here. We should use it also for the build scripts, since for the moment we say that we submit to the same partition, so users would expect to see that in the build scripts, too, since they submit in the same partition.

[teojgo]

@teojgo I think you are correct here. We should use it also for the build scripts, since for the moment we say that we submit to the same partition, so users would expect to see that in the build scripts, too, since they submit in the same partition.

Yes for the moment it is used for both.

[vkarak]

lgtm

[vkarak]

@branfosj With this feature you will now be able to define your partition as follows:

{
    'name': 'mypart',
    'scheduler': 'slurm',
    'launcher': 'srun',
    'prepare_cmds': ['module purge'],
    'modules': ['bluebear']
}

The prepare_cmds will always be emitted before any commands that load the test environment. Let us know if this is sufficient.

[branfosj]

Thanks