[tonyganch]

I've upgraded Discord notifier to accept color in template. It's the color of the embed frame, and right now there are only three options: red, green and grey. By passing the color via template, we allow developers to make better integrations. For example, one can choose different colors based on severity, or project, or any other logic that is useful to a team.

https://discord.com/developers/docs/resources/channel#embed-object-embed-structure

1. Documentation says that color must be of type integer, but in reality Discord accepts untrimmed strings as well, as long as they contain a 10-base integer.
2. I've moved default colors to the template, for two reasons: (a) Slack defines default color values outside of slack/slack.go, so I used it as example; (b) it makes it easier to find everything default in one place, be it default title or default color.
3. The type is now string instead of int, and it has its own pros and cons, I'm hoping someone will advise me on the best approach. I haven't found a super easy way to get int out of template without some sort of string-to-int conversion. And with parsing, we need to know if its 10-base int inside a string or 0x. And it seems like doing parsing on our side just adds more places where something might go wrong, and it doesn't feel worth it. Discord API works okay with parsing on their end as long as colors are 10-base. It's a simpler and safer approach in my opinion, so I did that.

This is my first PR to alertmanager, so if there are any other requirements for the PR, i'll be happy to update it.
Also, I will be happy to add support for the whole embed struct based on current Discord API if this change is welcome, I believe this will give more freedom to developers to setup their integrations.

Screenshot of the alert with custom color, and thumbnail (thumbnail is not part of this PR):

[arsalanyavari]

Hi Prometheus team and @tonyganch

@tonyganch, first of all, thank you for working on this and opening this PR.

I would like to ask the Prometheus team (@TheMeier and @SoloJacobs) about their plans regarding this PR and feature. Customizable embed colors are still missing in Alertmanager's Discord integration today, even though this is a very common and needed capability (especially for visually distinguishing alert severities like critical, warning, and info that we make them different with labels).

If the Prometheus team is on board with moving forward with this feature, I think the current implementation seems no longer compatible with main due to several major architectural and structural changes in the codebase since this PR was opened.
So @tonyganch, do you have the availability to update and rebase these changes against the latest codebase? If you don't, I can take this over and submit an updated PR compatible with current main.

Thanks!

[ultrotter]

Can we have a comment here what color it is, please?

[arsalanyavari]

It's dark red (#992D22 / 0x992D22), which was the original colorRed constant in discord.go.
Will definitely add a clarifying comment like {{/* Red: #992D22 */}} during the rebase.

[siavashs]

I think we can merge this if it is rebased and merge conflicts are resolved.
Also I am working on a google chat integration and might introduce template functions and a color pallet for users to choose from. That does not fix the specific discord issue here but changes the template/config side of what this PR is trying to do.

[arsalanyavari]

I think we can merge this if it is rebased and merge conflicts are resolved. Also I am working on a google chat integration and might introduce template functions and a color pallet for users to choose from. That does not fix the specific discord issue here but changes the template/config side of what this PR is trying to do.

Thanks for the feedback @siavashs

I'll give @tonyganch a couple of days to see if he's available to rebase and address @ultrotter's comment. If he doesn't have the time or doesn't respond, I'll take it over and open a fresh, rebased PR against current main.

[SoloJacobs]

@arsalanyavari Could you also describe how you intend to use this feature? Templating is always a bit more fragile than other approaches. Currently, we (the maintainers) couldn't come up with a better approach, and we are happy to land this PR if templating is the only way. But perhaps there is something with better ergonomics? For this we need to understand the use-case though.

[arsalanyavari]

@arsalanyavari Could you also describe how you intend to use this feature? Templating is always a bit more fragile than other approaches. Currently, we (the maintainers) couldn't come up with a better approach, and we are happy to land this PR if templating is the only way. But perhaps there is something with better ergonomics? For this we need to understand the use-case though.

Thanks for the question @SoloJacobs!

The main use case is visual triage by severity. Right now, every firing alert in Discord has a hardcoded red frame, so an informational notification (like a routine RAID check or backup notice) looks just as alarming as a critical outage. We'd like to be able to tell critical (red), warning (yellow), and info (grey/blue) apart at a glance to reduce alert fatigue.

Templating makes sense here because different teams use different labels (some use severity, others priority or tier), very similar to how slack_configs.color works.

For ergonomics, the main annoyance right now is having to calculate and write raw decimal integers like 10038562. If we support hex codes (e.g. #E74C3C) or standard keywords (danger, warning, info) in the template and convert them to Discord's integer in Go, it would be much more user-friendly.

Does that sound like a reasonable direction?

[arsalanyavari]

Hi @SoloJacobs (and @ultrotter),
Just following up on my comment above #3675 (comment). Does this direction (supporting hex codes like #E74C3C and keywords like danger/warning/info with templating) sound good to you?
If you're on board, I'd be happy to start implementing it!