The update is live! See T272523 for the new connection scheme.

To find out, which databases are stored, there's few options:

1. Connect to meta_p and get the value of the column slice in table wiki
2. Connect to each cluster and do show databases
3. Get clustering results from https://noc.wikimedia.org/conf/, where they are stored in dblists/s<number>.dblist

As we are querying meta either way, the easy solution is to store cluster mapping in Sources, but it might be better to submit patch to Toolforge Python library... Or at least talk to its developer about this update.

@LostEnchanter Thats great! I believe we connect to the shards locally, and in our scripts we match and connect to appropriate shard? I am not sure what we ask toolforge library devs since when we connect locally we use pymysql anyways. I see they have made some changes wrt this recently, those changes may be worth a look.
Storing in Sources table is brilliant if we want to do it ourselves!

Update status:

Port forwarding from Python is way less trivial when I expected - partly probably because of lack of experience with pure ssh, partly because of lack of examples I could find. If anyone could make port forwarding to the databases work, for example, using Fabric or sshtunnel, and could connect with me with their code, I would be grateful, as searching for errors I get when trying to forward ports returns nothing.

For now working on this is feature is postponed as having lower priority then web service.

@LostEnchanter: Hi! This task has been assigned to you a while ago. Could you maybe share an update? Do you still plan to work on this task, or do you need any help?

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