fixes #10756, #13500 - developer api and PXE-less reprovisioning

[iNecas]

This PR adds ability to run the script provision template via remote
execution and reboot the host, which effectively brings PXEless
provisioning into Foreman.

This feature uses a new developer API of the remote execution plugin.

Any plugin (or core) and define a feature at initialization:

RemoteExecutionFeature.register(:reprovision, N_("Reprovision"),
                               :description => "Reprovision the host via script",
                               :provided_inputs => ["script"])

The mapping between the feature and templates can be made via
'Administer -> Remote Execution Features'.

composer = JobInvocationComposer.for_feature(:reprovision, host, :script => "grubby...") composer.save! composer.trigger

When seeding a template, there is a new meta feature, which allows to
assign some template as default to the specified feature.

The template mapping is now limited to just one template, but in future, we
can extend that to allow different mappings through organizations, but lets
keep it simple first.

TODO:

• moar tests
• API and Hammer CLI for reprovision
• permissions
• documenting in manual

[iNecas]

For the reprovisioning to work on centos7, I had to update the script template slightly (ommiting the --copy-default):

grubby --add-kernel=$KERNEL --initrd=$INITRD --title "<%= @host.operatingsystem %>" --make-default  --args="ks=<%= foreman_url('provision')%>"

[iNecas]

It gives the best results in combination with theforeman/smart_proxy_remote_execution_ssh#20, that fixes rebooting

[iNecas]

I had to do this in order to ssh keys snippet to work with global proxy, I will probably open a separate PR and issue for this.

[iNecas]

#156

[stbenjam]

I like the approach in general, do we have a way to get the results back to the caller when it completes? This is also a separate problem by being able to show some structured results (e.g. package install case -> return the version installed), but we should at least support the ability to send a success/fail message back now, perhaps by letting the caller register itself as an observer of the invocation?

[iNecas]

Even in katello today, we're using the task object to get the output. So we might just get the task data simpler to get after triggering, so that the plugin can consume that.

[stbenjam]

If a Katello user kicks off a package install, the UI will probably stay the same as it is today, so that composer.trigger should return the task ID and Katello can show the same progress bar it does now, right?

I was thinking of a case where you have a plugin that kicks off a remote execution task, and wants to get the results of that sent somewhere else (eventually).

For example, foreman_salt has a 'Run Salt' button on the Hosts page. I'd like to notify a ReportImporter service when it completes, because then the service could look at the remote execution task output, and parse that output as a Report.

Maybe there's other ways to accomplish this already - like call Remote Execution from within a task itself and just block on the REX task to complete, instead of doing something like the observer pattern.

Hopefully I'm explaining what I mean 😕 ❓

[iNecas]

I see. In your case, I would probably rather go into triggering the task from within the orchestration action in salt: so you would get the composer from the developer API and the calling plan_action(RunHostsJob, composer) from your action: thin this case, the action would get part of your orchestration and you could chain the actions as dynflow allows to do. We might provide some helper on doing so (maybe we will get to it even with Katello… we will see)

[iNecas]

FYI: I've opened separate PR with just developer API #148, in order to move other features forward (such as Katello integration), and getting some time to get the pxe-less reprovision finished (API/CLI and UI updates)

[iNecas]

I've opened the power action templates in separate PR #155

[iNecas]

closing in favor of #159, I will try also to extend the build button with the toggle there