Override time-zone option when initializing database

[glensc]

Initializing a database with a config that specifies default-time-zone ends up with an error:

Fatal error: Illegal or unknown default time zone 'Europe/Tallinn'

This adds a workaround to the problem to force the system timezone (similarly to --initialize-insecure, --skip-networking options used in init db process), so the database can be initialized, and timezones be imported after database init.

Implements solution described at:

• Using option --default-time-zone at first run makes mysql_install_db script fail #543 (comment)

Why this is brought up again? It's because a config file offers a unified way to configure MySQL instance, compared to setting up environment variables for different systems (docker run, docker-compose, kubernetes, ...).

---

Local build commands:

git clone --depth 1 -b patch-1 https://github.com/glensc/docker-library-mysql mysql-pr739 && cd mysql-pr739
docker build 5.6 -t mysql:5.6_pr739 -f 5.6/Dockerfile.debian
docker build 5.7 -t mysql:5.7_pr739 -f 5.7/Dockerfile.debian
docker build 8.0 -t mysql:8.0_pr739 -f 8.0/Dockerfile.debian

Local test commands:

docker run --rm -e MYSQL_ALLOW_EMPTY_PASSWORD=1 mysql:5.6_pr739 gosu mysql bash -x /entrypoint.sh mysqld --default-time-zone=Europe/Tallinn
docker run --rm -e MYSQL_ALLOW_EMPTY_PASSWORD=1 mysql:5.7_pr739 gosu mysql bash -x /entrypoint.sh mysqld --default-time-zone=Europe/Tallinn
docker run --rm -e MYSQL_ALLOW_EMPTY_PASSWORD=1 mysql:8.0_pr739 gosu mysql bash -x /entrypoint.sh mysqld --default-time-zone=Europe/Tallinn

[yosifkit]

Yeah, time zones are not available until after initialization, so this makes sense to add. CC @tianon & @ltangvald

I think alternatively they can set TZ, but it makes sense to support it in config files and flags too.

[tianon]

I don't love it, but it makes sense. 👍