I noticed this because of the question I asked here. With a plain
docker run percona:5.6
or
docker run percona:5.7
the logs show that mysqld shuts down before starting up again for good. There are no errors:
2020-08-02T00:17:56.392322Z 0 [Note] mysqld: ready for connections.
Version: '5.7.30-33' socket: '/var/lib/mysql/mysql.sock' port: 0 Percona Server (GPL), Release 33, Revision 6517692
mysql: [Warning] Using a password on the command line interface can be insecure.
Warning: Unable to load '/usr/share/zoneinfo/iso3166.tab' as time zone. Skipping it.
Warning: Unable to load '/usr/share/zoneinfo/leapseconds' as time zone. Skipping it.
Warning: Unable to load '/usr/share/zoneinfo/tzdata.zi' as time zone. Skipping it.
Warning: Unable to load '/usr/share/zoneinfo/zone.tab' as time zone. Skipping it.
Warning: Unable to load '/usr/share/zoneinfo/zone1970.tab' as time zone. Skipping it.
mysql: [Warning] Using a password on the command line interface can be insecure.
2020-08-02T00:17:59.781414Z 0 [Note] Giving 0 client threads a chance to die gracefully
2020-08-02T00:17:59.781467Z 0 [Note] Shutting down slave threads
...
2020-08-02T00:18:02.031635Z 0 [Note] mysqld: Shutdown complete
This behavior is consistent across runs, and across Mac and Ubuntu. Is there anything I can do to prevent this? And what would be a good way to check whether it's up for good? It seems like there might not be one, besides just waiting. It doesn't happen on 8.0.
The first run of mysqld is an initialization of the data directory in a bootstrap mode.
The second run is mysqld starting as a service will all the authentication and initialization that the boostrap provided.
Percona dockerhub reference (under: "No connections until MySQL init complete" header) indicates that when a connection is available its ready to start.
The source code for the entry point is at this github url.