Allow customizing notification templates per project

[vindex10]

There is a way to have customizable templates for dispatch today, by mounting a volume with a customized templates dir as part of the docker compose:

  web:
    image: dispatch-local
    ...
    volumes:
      - "../dispatch-templates/messaging-email-templates:/usr/local/lib/python3.11/site-packages/dispatch/messaging/email/templates"

This approach does allow to customize the templates "deployment"-wide.

In this PR I suggest a small extension of this functionality. You can create a folder per project (identified by project id):

dispatch/messaging/email/templates/project_id/<project_id>/base.mjml

This will be used at the first place if exists, otherwise will gracefully fall back to the default template like "/templates/base.mjml".

I was a bit afraid to use "slug" of the project name, because this requires more careful work on escaping system paths and making sure we don't expose something by engineering a weird project name. This can be expanded in future though, by introducing another subdir "templates/project_slug/<project_slug>".

[kevgliss]

This looks great @vindex10! As this approach fallbacks gracefully, I see no reason why it can't be merged. Thanks for the contribution.

As far as documentation, we don't currently have a good space for something like this. Maybe we could create new page for "Messaging" related settings here: https://netflix.github.io/dispatch/docs/administration/settings ?

[vindex10]

Sounds good! I could also include information about the recent markdown enhancement in there :)

[mvilanova]

@vindex10 can you run black against the files you changed? It will fix the formatting issues the lint tests are complaining about.

[vindex10]

Yes, of course, i will change this together with adding the page to the docs!

[vindex10]

Could you rerun the playwright tests please? They seem to have failed because of the network problem

[kevgliss]

I think this looks good @vindex10 if you're happy with it I can merge it in.

[vindex10]

I definitely am, @kevgliss :) please do! Thank you!

[kevgliss]

Thanks! This will be added in our next release.