Fix configsvr with user/pass env vars on 5.0 & 6.0

[yosifkit]

Since 5.0, setting the sharding.clusterRole/--configsvr requires it to be part of a replica set so this fixes part of #509 (for --configsvr). Not certain we need to do anything for --shardsvr since they shouldn't use the entrypoint user/pass or initdb.d scripts there.

BadValue: Cannot start a configsvr as a standalone server. Please use the option --replSet to start the node as a replica set.
try 'mongod --help' for more information

Technically, adding --auth (via adding user/pass) also requires a keyFile for a replset, but that is something the user needs to add (not something we can fix in the entrypoint)

$ docker run -it --rm \
-v "$PWD/data:/data/configdb" \
-v "$PWD/keyfile:/keyfile:ro" \
--user [data & keyfile directory owner] \
--env MONGO_INITDB_ROOT_USERNAME=admin \
--env MONGO_INITDB_ROOT_PASSWORD=password \
--name mongo-cfg \
mongo:6.0 --configsvr --replSet rep --keyFile /keyfile/test.key

(I'd recommend users also set --hostname when using replica sets depending on how they set up members in their replica configuration rs.init(...).)

[theDanielJLewis]

Will this or a similar fix ever be merged?

[tianon]

As noted by @yosifkit in #717 (comment), we're still not sure this is actually a "correct" fix (and frankly the entrypoint scripts here are already doing way more than we're comfortable with maintaining, which is part of why we avoided adding even the basic functionality they currently have for so long).