How to migrate from mysql to postgres service?

[iVegas]

Mattermost 11 will support only Postgres databases. This repo used MySQL database before Mattermost 10.
Will there be any additional compose file provided for the example of the migration process?

[alpha0010]

I ran through a similar process recently (native install+mysql -> docker install+postgres). Here are some notes from my process in case they help.

• Copy production mysql data dir to staging server
• On the staging server, start docker run -v ./mysql_data:/var/lib/mysql -d mysql:<version> --default-authentication-plugin=mysql_native_password
• Create a throwaway blank staging MM https://docs.mattermost.com/install/install-docker.html
• Mostly follow https://docs.mattermost.com/deploy/postgres-migration-assist-tool.html , but with the following tweaks
  • <address> in the following two steps found via docker inspect -f '{{range.NetworkSettings.Networks}}{{.IPAddress}}{{end}}' <the_container>
  • MYSQL_DSN looked like: root:<password>@tcp(<address>:3306)/mattermost
  • POSTGRES_DSN looked like: postgres://mattermost:<password>@<address>:5432/mattermost?sslmode=disable
  • pgloader always crashed until I edited migration.load to reduce values to: workers = 2, rows per range = 4000, prefetch rows = 4000, batch rows = 1000
  • I executed pgloader via: docker run -it --rm --network=host -v $(pwd):/home/migration mattermost/mattermost-pgloader:latest pgloader migration.load > migration.log
  • After running pgloader, I had to ALTER USER mattermost RESET SEARCH_PATH; within docker exec -it mattermost-postgres-1 psql mattermost
• Once this was all complete, set up production MM with volumes/app/mattermost/data from your existing files data and volumes/db/postgres/data copied from the corresponding folder on the staging server