As Bitwarden states in the core readme (https://github.com/bitwarden/core#requirements) "These dependencies are free to use." And if you lookup the licensing on MSFTs website (https://www.microsoft.com/en-us/sql-server/sql-server-2017-p...) you can see that the SQL Server Express version is free.
Note: No, I'm not an MSFT employee and not related in any way to the mentioned company. I'm just a (not so regular) human being who first looks up information before posting statements.
The README requires SQL Server so I might be excused thinking that it would work only with that software. Nice to know that it does work on the free version too. I googled and looked on MS site and didn't find out if SQL Server Express exists for Linux too, but I'm on my phone right now. I only managed to involuntarily download a .exe :-)
There you go: https://hub.docker.com/r/microsoft/mssql-server-linux/
:)
Basically, my flow chart for DB selection:
Do you have an enterprise worth of money to burn on the deployment and maintenance? Oracle.
Are you deploying to Windows? MSSQL.
Else: Postgres.
Even then I'd actively try to avoid it.
Source: three years installing, configuring and supporting it.
†: Now that I've used it twice, I move that we make an "enterprise worth" a unit of measurement of money, like a "Library of Congress" is a unit of measurement of storage.
It all sounded really good until this point. I was even going to say you could add support for postgres, but I don't know a lot of open source devs who are using. NET.
SQL Server 2017, really? Interesting choice. Open source but we have to pay licenses for the database if we want to self host. I wonder what was wrong with PostgreSQL or MySQL even if they're using .NET Core as a language.
Edit: there is an issue for that https://github.com/bitwarden/core/issues/10