Documentation example with custom config flag does not work

[graforlock]

For example, when you try:

docker run --name some-mongo -d mongo --config /etc/mongod.conf.orig

Which is re-using existing configuration, then you are getting exit code 100 and the container doesn't start.

[tianon]

This is a problem with the specific contents of /etc/mongod.conf.orig (not the example in the image description, which doesn't reference that file).

Digging into it interactively, I see that config file uses /var/log/mongodb/mongod.log for logging -- after attempting to start using that config, I checked that log file and found (not unexpectedly): {"t":{"$date":"2022-11-28T23:08:24.988+00:00"},"s":"E", "c":"CONTROL", "id":20557, "ctx":"initandlisten","msg":"DBException in initAndListen, terminating","attr":{"error":"NonExistentPath: Data directory /var/lib/mongodb not found. Create the missing directory or specify another path using (1) the --dbpath command line option, or (2) by adding the 'storage.dbPath' option in the configuration file."}}

(We don't configure/use /var/lib/mongodb in this image, but rather use the built-in default /data/db of mongod itself.)