There are four time zones to consider:
NOW ()etc. of SQL statements
Added ʻENV TZ Asia / Tokyo
to Dockerfile` to support
Corresponding by setting
TZ = Asia / Tokyo in the environment variable
config.time_zone = 'Tokyo'
config.active_record.default_timezone = :local
DB Connect to each DB of development environment and production environment and execute the following query
ALTER DATABASE db_name SET timezone TO 'Asia/Tokyo';
Since it is the writing method for Postgres, the writing method may differ depending on the type of DB.
It will be reflected when you reconnect to the DB.
rails: db: migrate will restore the timezone, but it's okay because you rarely write SQL statements in Rails in the first place.
There seems to be a way to set environment variables in docker-compose.yml, but it didn't work.
-Rails time zone summary-Qiita