Mattermost-server: Add OnPluginStatusesChanged hook

[lieut-data]

Add the following hook, emitted whenever we call App.notifyPluginStatusesChanged:

func OnPluginStatusesChanged(c *Context) error

This hook event will not contain a payload: it is the responsibility of the plugin to fetch the plugin statuses so as to avoid race conditions with notifications going out. While this is currently possible via GetPlugins and a series of GetPluginStatus calls, let’s also add a plugin API method to streamline this:

func GetPluginStatuses() ([]*model.PluginStatus, *model.AppError)

Note that it’s not necessary to broadcast plugins statuses to other servers – this hook event is only local to the current server, and in fact the plugin statuses may vary between servers.

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JIRA: https://mattermost.atlassian.net/browse/MM-19267

[joshuabezaleel]

Hi @lieut-data , any pointer on which part of the codebase I can start reading if I am interested in this?
Thank you very much :slightly_smiling_face:

[lieut-data]

Hey @joshuabezaleel! I don't know of a resource that explains the creation of apis and hooks for plugins, but I can point you at https://github.com/mattermost/mattermost-server/pull/13647 for an example of a recently added API method, and https://github.com/mattermost/mattermost-server/pull/10178 for a recently added hook.

If you're still interested, let me know!

[joshuabezaleel]

Hi @lieut-data , if it's okay with you I would like to ask a question.

What's the difference between the GetPluginStatuses API method that you proposed above and the one written here?

Thank you! :slightly_smiling_face:

[lieut-data]

@joshuabezaleel, the one you linked to on the App structure will indeed be the implementation for the new plugin API, but it's just not currently exposed to plugins.

[fedealconada]

if this issue is idle, I can take it @lieut-data

[lieut-data]

Thanks, @fedealconada! @joshuabezaleel already has a PR up, and I've just been iterating with some feedback on it, so I think it's in a good state for now.