CDS is unusable: API recieves database auth response 10

[shueja]

Hello.
I am trying to set up CDS 0.47.0 from binaries as provided in the docs. I'm using postgresql 13 for my database. However, when I get to setting up the database, I run into a several-part problem.

1. The docker command uses postgres 9.6, which probably means neither the docs nor CDS itself has been updated in a long time. This leads to
2. The new default encryption method in postgres is scram-sha-256.
3. CDS does not support scram-sha-256 (yet).
   This is probably the cause of the following failure:

Reading configuration file @ conf.toml
Starting service api
2020-12-29 09:58:27 [INFO] api> cds-api-zealous_hypatia configuration applied
2020-12-29 09:58:27 [INFO] observability> initializing observability for api/cds-api-zealous_hypatia
2020-12-29 09:58:27 [INFO] Registing service api(*service.Common) cds-api-zealous_hypatia
2020-12-29 09:58:27 [INFO] api> Service registered
2020-12-29 09:58:27 [INFO] Starting CDS API Server 0.47.0+cds.13856
2020-12-29 09:58:27 [ERROR] engine is unavailable for download, this may lead to a poor user experience. Please check your configuration file or the /var/lib/cds-engine directory
2020-12-29 09:58:27 [ERROR] cdsctl is unavailable for download, this may lead to a poor user experience. Please check your configuration file or the /var/lib/cds-engine directory
2020-12-29 09:58:27 [INFO] Initializing mail driver...
2020-12-29 09:58:27 [INFO] Initializing feature flipping with izanami
2020-12-29 09:58:27 [INFO] Initializing local objectstore...
2020-12-29 09:58:27 [INFO] ObjectStore> Initialize Filesystem driver on directory: /var/lib/cds-engine/artifacts
2020-12-29 09:58:27 [INFO] Initializing database connection...
2020-12-29 09:58:27 [ERROR] api> Serve: cannot connect to database: pq: unknown authentication response: 10
2020-12-29 09:58:27 [ERROR] api> Service exiting with err: context canceled
Service has been stopped: api context canceled

I have tried going into pg_hba.conf and changing the encryption to md5, but its auto-upgrade functionality re-encrypts the passwords as scram. Therefore, CDS cannot access the database.

Possible Solutions/workarounds
CDS could support SCRAM. I see this is being raised in Discussions.
In the meantime, is it possible to set up PostgreSQL 13 with md5 encryption only, or do I have to roll back to 9.6 or another version?

[ozonep]

@shueja-personal PostgreSQL versions up to v12 are working fine, v13 does not.
I assume this is due to Go package used for Postgres connection, it's not actively maintained anymore, hence all these errors.
It's not crucial, you'll be just fine with v12.

[yesnault]

support for scram-sha-256 will be follow in #5644