Webhook External Command

[jolheiser]

Related to #1089

Preface, a plugin system would potentially be nicer, but also more complicated. I've opted to open this proposal to see if there is interest.

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I'm in the beginning stages of working out how an external command could work.
In my opinion this could cover a vast majority of cases, as the command could also do any data processing and HTTP calls as necessary.

name: custom-py
# Not sure if this should be a local path or URL. If local, Gitea needs a way to serve it e.g. in the custom/img folder
image: /path/to/image.png 
command: [python, /usr/local/bin/custom.py]
form:
  - title: Channel ID
    help: The channel to post to
    required: true

Things inside form would be used by Gitea to present the webhook form. Probably by transforming the title e.g. channel_id from above.

I'm thinking the current gitea JSON payload could be sent to the command via stdin.
I'm not 100% sure how to pass along form inputs, perhaps an enclosing JSON object ?

{
  "form": {...},
  "payload": {...}
}

Then the command can unmarshal the JSON and do whatever it needs to.

[zeripath]

This seems like a potential solution - of course windows users will cause no limit of trouble.

If we do this - do not use exec.Command but rather extend the modules/process/manager.go to have a nicer Exec that will take a readers and write to writers. Then the process becomes cancellable from the admin page etc.