FEATURE: "mongo-url" (MONSTACHE_MONGO_URL) to separate for reading data and writing configs

[apetrik-nh]

Hello @rwynn .

I would like Monstache to read from the secondary MongoDB replica. But in the case I point Monstache to the MongoDB with "secondaryPreferred" in the connection string, Monstache is unable to write the configs (direct reads marker and change stream timestamp) so we loose the state on the big DB.

It seems like an absolutely logical requirement but I didn't find anything in the documentation to achieve this. As far as I understand "mongo-config-url" (MONSTACHE_MONGO_CONFIG_URL) is used for different case when MongoDB is running as a cluster.

Thank you,
Andrei