Changed to be able to read user-scope datastore value via '{{ st2kv.user }}' notation.

[userlocalhost]

Background

The change of (#3199) and document of Datastore say StackStorm supports the I/F to get datastore value via {{ st2kv.system }} and {{ st2kv.user }}.

Related Issue

• (Question) Why does DatastoreService inhibit from handling non system-scope value? #4451 (comment)

Problem

StackStorm didn't have an implementation to accept {{ st2kv.user }} expression.

Change

This implements the processing to accept {{ st2kv.user }} notation and render it to user-scope value in datastore which is associated with executed user.

[Kami]

I'm fine with this approach, but we should document this behavior (something along the lines that st2kv.user.foo will only work for actions which have user context attached to and and are executed via the API or similar).

Also, what will happen if we are unable to read user from the context and action author references st2kv.user in a default value? I assume it will throw a template rendering error.

If that's the case, we should consider doing the following:

1. Add a test case for this scenario
2. Instead of generic template rendering error being thrown, we should see if we can throw a more user-friendly error

Another option is to default it to the system user (stanley), we do this in other places.

[Kami]

Besides that, I'm fine with this change.

Nice work 👍

[userlocalhost]

Thank you very much for your review. I got it. I'll do that soon!

[Kami]

@userlocalhost Can you please also open st2docs PR which documents this behavior?

[userlocalhost]

Thank you again for your review and telling me advices to brush up.

Also, what will happen if we are unable to read user from the context and action author references st2kv.user in a default value?

I've taken care of this problem by the idea that system user fills in for the one.

[userlocalhost]

I fixed the points that you mentioned, would you please review this patch, @Kami?

[Kami]

Thanks, I will have a look later today.

[userlocalhost]

Thank you very much!

[Kami]

Merged, thanks.

Please also open a corresponding st2docs PR when you get a chance :)

[userlocalhost]

I think we don't have to amend st2docs because the explanation of this feature has already been described at the Datastore page in st2docs.

This is an excerpt from it.

Also, you can refer to user variables in actions or workflows. The Jinja syntax to do so is {{st2kv.user.date_cmd}}.

Note that the notion of st2kv.user is available only when actions or workflows are run manually. The notion of st2kv.user is non-existent when actions or workflows are kicked off via rules. So the use of user scoped variables is limited to manual execution of actions or workflows.

I think this description is good enough to explain how to use this and what limitations are.