As far as post from people who have done it, here you go:
The most intriguing is this “official” doc from Mattermost itself. The table right at the very end of the page indicates that I can use Aurora RDS for MySQL:
https://docs.mattermost.com/deployment/scaling.html
This person is using a RDS MySQL DB
Another example:
As far as SQL settings (password and key edited):
“SqlSettings”: {
“DriverName”: “mysql”,
“DataSource”: “mmuser: password @tcp(172.16.3.114:3306)/mattermosm?charset=utf8mb4,utf8\u0026readTimeout=30s\u0026writeTimeout=30s”,
“DataSourceReplicas”: ,
“DataSourceSearchReplicas”: ,
“MaxIdleConns”: 20,
“ConnMaxLifetimeMilliseconds”: 3600000,
“MaxOpenConns”: 300,
“Trace”: false,
“AtRestEncryptKey”: “key”,
“QueryTimeout”: 30
},