Aspire.Npgsql component does not create database

[alexwolfmsft]

When providing a custom name for a database, the builder.AddPostgresContainer("pg").AddDatabase("postgresdb") methods do not seem to create the database in the Postgres container. For example, with the following code:

var postgresdb = builder.AddPostgresContainer("catalog").AddDatabase("catalogdb");

var postgres = builder.AddProject<Projects.AspireSQL>("aspirepostgres")
                       .WithReference(postgresdb);

And:

builder.AddNpgsqlDataSource("catalogdb");

I receive this error:
PostgresException: 3D000: database "catalogdb" does not exist

When I use psql commands in the container to view the list of databases, it looks like this:

Should I expect to see a "catalogdb" database listed here?

The connection and query does work if I switch to AddDatabase("postgres") to use the default database.

[DamianEdwards]

This is by design. The database name is to ensure the appropriate connection information is provided but it's not intended that the database will be auto-created by the hosting APIs given all the variables that can impact database creation.

[eerhardt]

The database name is to ensure the appropriate connection information is provided but it's not intended that the database will be auto-created by the hosting APIs given all the variables that can impact database creation.

I think this is confusing, and not consistent with our other hosting APIs. The first call is "AddPostgresContainer", which creates a Postgres container. The second call is "AddDatabase", which doesn't create a database? That seems wrong that the same verb doesn't do the same thing.

[alexwolfmsft]

@eerhardt It's interesting you mention this because that's the exact reason I assumed it auto generated the db - it autogenerates a redis setup for you using similar methods/naming.

[eerhardt]

Re-opening to discuss this a bit more. I'm not sure the current behavior is the best we can do.

[alexwolfmsft]

Re-opening to discuss this a bit more. I'm not sure the current behavior is the best we can do.

I know you've seen #1168 as well, but just wanted to point out the other db components don't autogenerate the database either - this seems to be a Redis vs Databases inconsistency.

Some .NET tools have historically autogenerated databases for you locally, though I think that was only when using EF.

[DamianEdwards]

Redis is more akin to a service than a database, in that you get a Redis instance and connect to that. With databases, you typically get a server which hosts multiple databases, and the database is part of the connection detail. All that said, I'm more than happy to discuss further whether we think the Aspire.Hosting layer should do more to ensure the configured database is actually available.

/Cc @davidfowl @roji for their thoughts.

[mitchdenny]

The moment you start auto creating the database you need to start specifying things like collations and that kind of stuff.

The other part of the problem is that you have to figure out where you want to provision the database. If you say you want to do it in the AppHost then suddenly the app host needs to have client drivers for each database which could be dependency hell.

Then you get into lifetime considerations such as the AppHost not being around during deployment so you still need something else to create the database anyway.

Better off to face these considerations up front.

It is possible for a deployment tool like AZD to be enhanced to support creating the database since in the Azure ARM world a database is actually a resource in the resource provider. But this is certainly cloud platform dependent.

[IEvangelist]

Perhaps, we should consider renaming the AddDatabase API. It make more sense as AddDatabaseConnection to make it clearer, that it's not in fact adding a database, but rather a connection to one?

[mitchdenny]

LOL ... it is funny how we keep recycling nouns :) We just removed AddPostgesConnection(...) ... and now looking to add AddPostgres(...).AddDatabaseConnection(...) which does something different.

I've never been super enthused about AddDatabase(...) myself so I'm more than open to renaming it. I'm not sure AddDatabaseConnection(...) is any better. Perhaps we need something like SelectDatabase(...).

[DamianEdwards]

There's a PR out that adds a sample on how to initialize databases when using database containers now: dotnet/aspire-samples#61