You can do that, but there are a couple of things to keep in mind.

Different apps may only be compatible with certain database products and versions. I could be a real pain if you have to spin up a new version of a database and migrate just for one service that updated their dependencies or have to keep an old database version around for legacy software.

If you stop using a service then it’s data is still in the database. This will get bloated after a while. If the database is only for one service then wiping it out when you are done isn’t a big deal. However, if you use a shared database then you likely have to go in and remove schemas, tables, and users manually; praying you don’t mess something up for another service.

When each service has its own database moving it to another instance is as easy as copying all the files. If the database is shared then you need to make sure the database connection is exposed to all the systems that are trying to connect to it. If it’s all local then that’s pretty safe, but if you have services on different cloud providers then you have to be more careful to not expose your database to the world.

Single use databases don’t typically consume a lot of resources unless the service using it is massive. It typically is easier to allow each service to have its own database.

In many cases it should be fine to point them all at the same server. You’ll just need to make sure there aren’t any collisions between schema/table names.

Yes and no. Theoretically, yes you may use one database for all services. Historically it was even an old assumption and some services still ask you for a table prefix to allow various services to use the same db without clashes. However it’s no more recommended and you should absolutely avoid going this way.

But nothing blocks you to have several separate databases on the same server. Here your mysql docker container play the role of a database server. You can use the same container for different services using different databases. Create one specific user/database per service inside your container (you may wrap the official mysql image inside your own image to script its creation), then add it in your docker-compose file and make all your services depend on the same service.

Sure, I always do like that.

I do a database docker compose with all the databases so they will get named database-mysql database-mariadb and so on and then i share a docker network (example ’docker network create mariadb’) between the containers that need them. Now they can access directly at mariadb:3306 (in docker compose you can access by the name of the container if you are in the same network)

I hate when the only option those “all in one” containers with included database, which I need to backup separately then

Yes, you can.

Without going into specifics, you need to share the network of your DB stack with the stack of the client containers.

Yes and usually sane developers allow you to specify external mysql instances.

Delving into the politics many view docker as a standalone system that shouldn’t need external items so they leave their db internal. Which goes against having configurations external.

But then you have external databases that you need to know enough to setup ahead of time to allow the docker to use and now I gave myself a headache

You would expose the port to your host which makes the db acessible by anything running on the host, docker or native. Something like

`port

• 5432:5432 `

But I would recommend running a dedicated db for each service. At least that’s what I do.

• Simpler setup and therefore less error-prone
• More secure because the db’s don’t need to be exposed
• Easier to manage because I can independently upgrade, backup, move

Isn’t the point about containers that you keep things which depend on each other together, eliminating dependencies? A single db would be a unecessary dependency in my view. What if one service requires a new version of MySQL, and another one does not yet support the new version?

I also run all my databases via a bind mount

`volume

• ./data:/etc/postgres/data…`

and each service in it’s own directory. E.g. /opt/docker/nextcloud

That way I have everything which makes up a service contained in one folder. Easy to backup/restore, easy to move, and not the least, clean.

Not only it can be done but I think it is the way to go. You then have to manage permissions and backup only on one database, and the performance improves given that you let postgresql manage it’s own IO. It goes without saying that you should use postgresql instead of mysql

You’ll want to learn some database administration before you attempt this. Simpler to just give them all their own instance.