If you are using Ubuntu, you need to add sudo before all docker and docker-compose commands.
After starting up my Canasta repo for the first time, I am getting a "Error 503 Backend fetch failed / Guru Meditation" error.
This is an error that Varnish returns. In this case, it is most likely because it cannot access the Canasta container (containing Apache, PHP, MediaWiki, etc.) Wait a few minutes for it to go away. If after 10 minutes it does not go away, try to restart your Canasta stack (docker-compose down && docker-compose up -d).
When accessing my Canasta instance, I am getting "SSL protocol error" in the browser or "sitemap permission denied" in the Canasta job queue logs.
This probably means your .env file doesn't exist. Use .env.example as a starting point and change things as necessary.
You may see an error message like this:
ERROR: for db Cannot start service db: OCI runtime create failed: container_linux.go:380: starting container process caused: process_linux.go:545: container init caused: rootfs_linux.go:76: mounting "/home/ubuntu/Canasta-DockerCompose/_initdb" to rootfs at "/docker-entrypoint-initdb.d" caused: mount through procfd: not a directory: unknown: Are you trying to mount a directory onto a file (or vice-versa)? Check if the specified host path exists and is the expected type
This probably means your _initdb directory either doesn't exist or you named your SQL dump _initdb rather than putting it into a directory called _initdb. Delete whatever you had, (re)create the _initdb directory, add your SQL dump into it, and delete all volumes created. Run docker volume ls and use docker volume rm to delete those volumes.
You likely initialized Canasta already by starting it with docker-compose up -d, then placed the SQL file in _initdb. Please delete your MySQL data volume and place the SQL file in _initdb before trying to start Canasta again. Run docker volume ls and use docker volume rm to delete those volumes.