New method for docker link?

I’ve used the --link to spin up a docker container beside a running mysql_svr, which automatically grabbed the original’s env vars, and was able to script backups/loads with those.

created network, gave them their static IPs, can run the production services just fine…
but spinning up the temp_mysql with the network defined, even throwing in --link mysql_srv:production…it cannot connect, prompts for password.

doesn’t work even when hard coded in script…so that suggests there is no connection being made, but can ping between servers

what is the new method now days?