Reminder notification/email for Approvals

Description

Our team has only about 4 developers but we work varying schedules. We make full use of Approvals for MRs but as some have mentioned it's difficult to stay on top of reviews a developer needs to do as mentions in #769 and #765 (closed).

Proposal

My addition to the proposals above would be to add the possibility of configuring a nudge/reminder notification and/or email which is triggered periodically.

Some formats can be:

• Daily Digest - You get one aggregate email with all the MR awaiting your approval every morning around 7 AM your time.
• Threshold Days - You get an email/notification each day following X days without approving a MR. X being configurable.

Mentioned in issue #580

Have you taken a look at how Todos work ([documentation](https://docs.gitlab.com/ce/workflow/todos.html#sts=GitLab Todos))?

A Todo appears in your Todos dashboard when:

• an issue or merge request is assigned to you
• you are @mentioned in an issue or merge request, be it the description of the issue/merge request or in a comment

Todos also follow the notification mechanisms you choose: you can be warned by email if you want. So in your use case, instead of having an automatic system which would complexify things and add another setting in the app (which we try to avoid), it would be up to the person whose work needs to be reviewed, to add something like ping @usernameXY in the merge request, to trigger a notification to the person he wants to notify.

Added ~238305 label

Upvote on this. Make it a field in the external notifications Integrations (slack/hipchat/mattermost) that can accept a reminder cron, or something similar. Currently writing python to get around this by parsing open MR's from the API. Would love to have this as a native feature.

added Discussion feature proposal labels

@victorwu some customers showed interest in this feature (check with @jimash)

We like this feature in our deployment as well, any tentative due date for this yet?

I would also like to propose adding Daily Reminder email on approved MRs that are awaiting merge.

@smcgivern @sarrahvesselov :

This is tied to todos. So it seems we can re-use that abstraction here. One thought is to just start sending reminder todos based on a schedule, daily digest (as suggested above), etc. Would this be easier / a better first iteration instead of doing approvals specifically?

@victorwu I think that's an interesting idea!

1. Would that be a CE feature, or EE only?
2. Would this work with our existing notification settings (if you're opted out of the 'todos digest' for a project, your digest doesn't include todos from that project), or be global?

@victorwu Would this be an additional option to email? In other words, I can choose to receive an email every time someone pings me or receive it in daily digest format.

@smcgivern @sarrahvesselov : Haven't given it much detailed thought. Just wanted to verify that you folks agree that targeting approval notifications seems too narrow (and in this case, complex). And instead, focusing on notifications and todos makes more sense.

I think it makes sense that our current set up with todos and notifications is CE. And then if we build enhancements and customizations (daily digest, etc.), those would be EE options.

added EE Starter label

changed milestone to %Next 3-6 months

And instead, focusing on notifications and todos makes more sense.

Agreed @victorwu