Discord notifications

OpenMU can post what happens in the game to the channels of your Discord server:

Category	What is posted
Events	Mini games which open (e.g. Blood Castle), winners of mini games, invasions which start and end
CastleSiege	Guild registration, the start and the end of the battle, and the new owner of the castle
WorldNews	Boss kills, excellent and ancient items which monsters dropped, characters which reach a level milestone
Notices	Global notices which game masters send with the ! chat prefix

Each category is posted to its own channel through a Discord webhook. Categories without webhook aren't posted.

note

This works in the all-in-one deployment. In the distributed deployment, the events are already published, but there is no service yet which posts them to Discord.

Setting it up

1. Create the webhooks. In Discord, open the settings of a channel, go to Integrations → Webhooks, create a webhook and copy its URL. Do this for each channel which should receive messages.

2. Configure the webhooks for the server, through environment variables, e.g. in your docker-compose.override.yml:

   environment:
     - Discord__Webhooks__Events=https://discord.com/api/webhooks/...
     - Discord__Webhooks__CastleSiege=https://discord.com/api/webhooks/...
     - Discord__Webhooks__WorldNews=https://discord.com/api/webhooks/...
     - Discord__Webhooks__Notices=https://discord.com/api/webhooks/...

   Treat the URLs like passwords: everybody who knows one can post into the channel. That's why they are not part of the game configuration in the database, but of the configuration of the server process.

3. Activate the Game Event Publisher plugin in the admin panel (Plugins). It's disabled by default. In its configuration, you choose which events are published, which monsters are bosses and which levels are milestones.

4. Restart the server.

Settings

All settings are part of the Discord section of the configuration, so they can also be set in the appsettings.json of the server.

Setting	Default	Description
Webhooks__<Category>	—	The webhook URL per category, see the table above.
Language	en	The language of the messages. English (en) and German (de) are available. Names of maps, monsters and items are translated, too.
EventAnnouncingServerIds__0, __1, …	all	The identifiers of the game servers which announce mini games and invasions. When several game servers run the same events, set it to one of them to avoid duplicate messages.
MaximumQueuedMessages	100	The number of messages per webhook which can wait to be sent. When there are more, the oldest ones are dropped.

Good to know

• Times like "the entrance closes in 5 minutes" are posted in a way that each Discord user sees them in their own time zone and language.
• Rate limits: Discord accepts about 30 messages per minute per webhook. When more happens, OpenMU combines up to 10 messages into one post and waits for Discord, so nothing gets lost unless the queue overflows.
• Mini games like Blood Castle open all their levels at the same time; this is announced only once.
• Mentions are disabled, so a text of a player like @everyone can't ping anybody.
• Make your notices channel an Announcement channel: other Discord servers, e.g. the ones of guilds, can then follow it and get the messages copied into their own channel.