nixos/postgresql: drop ensurePermissions, fix ensureUsers for postgresql15

Closes #216989

First of all, a bit of context: in PostgreSQL, newly created users don't
have the CREATE privilege on the public schema of a database even with
`ALL PRIVILEGES` granted via `ensurePermissions` which is how most of
the DB users are currently set up "declaratively"[1]. This means e.g. a
freshly deployed Nextcloud service will break early because Nextcloud
itself cannot CREATE any tables in the public schema anymore.

The other issue here is that `ensurePermissions` is a mere hack. It's
effectively a mixture of SQL code (e.g. `DATABASE foo` is relying on how
a value is substituted in a query. You'd have to parse a subset of SQL
to actually know which object are permissions granted to for a user).

After analyzing the existing modules I realized that in every case with
a single exception[2] the UNIX system user is equal to the db user is
equal to the db name and I don't see a compelling reason why people
would change that in 99% of the cases. In fact, some modules would even
break if you'd change that because the declarations of the system user &
the db user are mixed up[3].

So I decided to go with something new which restricts the ways to use
`ensure*` options rather than expanding those[4]. Effectively this means
that

* The DB user _must_ be equal to the DB name.
* Permissions are granted via `ensureDBOwnerhip` for an attribute-set in
  `ensureUsers`. That way, the user is actually the owner and can
  perform `CREATE`.
* For such a postgres user, a database must be declared in
  `ensureDatabases`.

For anything else, a custom state management should be implemented. This
can either be `initialScript`, doing it manual, outside of the module or
by implementing proper state management for postgresql[5], but the
current state of `ensure*` isn't even declarative, but a convergent tool
which is what Nix actually claims to _not_ do.

Regarding existing setups: there are effectively two options:

* Leave everything as-is (assuming that system user == db user == db
  name): then the DB user will automatically become the DB owner and
  everything else stays the same.

* Drop the `createDatabase = true;` declarations: nothing will change
  because a removal of `ensure*` statements is ignored, so it doesn't
  matter at all whether this option is kept after the first deploy (and
  later on you'd usually restore from backups anyways).

  The DB user isn't the owner of the DB then, but for an existing setup
  this is irrelevant because CREATE on the public schema isn't revoked
  from existing users (only not granted for new users).

[1] not really declarative though because removals of these statements
    are simply ignored for instance: https://github.com/NixOS/nixpkgs/issues/206467
[2] `services.invidious`: I removed the `ensure*` part temporarily
    because it IMHO falls into the category "manage the state on your
    own" (see the commit message). See also
    https://github.com/NixOS/nixpkgs/pull/265857
[3] e.g. roundcube had `"DATABASE ${cfg.database.username}" = "ALL PRIVILEGES";`
[4] As opposed to other changes that are considered a potential fix, but
    also add more things like collation for DBs or passwords that are
    _never_ touched again when changing those.
[5] As suggested in e.g. https://github.com/NixOS/nixpkgs/issues/206467

14 files changed, 45 insertions, 37 deletions

diff --git a/nixos/tests/dex-oidc.nix b/nixos/tests/dex-oidc.nix
index 37275a97ef0f..e54ae18ca937 100644
--- a/nixos/tests/dex-oidc.nix
+++ b/nixos/tests/dex-oidc.nix
@@ -49,7 +49,7 @@ import ./make-test-python.nix ({ lib, ... }: {
       ensureUsers = [
         {
           name = "dex";
-          ensurePermissions = { "DATABASE dex" = "ALL PRIVILEGES"; };
+          ensureDBOwnership = true;
         }
       ];
     };
diff --git a/nixos/tests/ferretdb.nix b/nixos/tests/ferretdb.nix
index 9ad7397ade80..7251198af77d 100644
--- a/nixos/tests/ferretdb.nix
+++ b/nixos/tests/ferretdb.nix
@@ -39,7 +39,7 @@ with import ../lib/testing-python.nix { inherit system; };
             ensureDatabases = [ "ferretdb" ];
             ensureUsers = [{
               name = "ferretdb";
-              ensurePermissions."DATABASE ferretdb" = "ALL PRIVILEGES";
+              ensureDBOwnership = true;
             }];
           };
 
diff --git a/nixos/tests/freshrss-pgsql.nix b/nixos/tests/freshrss-pgsql.nix
index 055bd51ed43d..c685f4a8159b 100644
--- a/nixos/tests/freshrss-pgsql.nix
+++ b/nixos/tests/freshrss-pgsql.nix
@@ -22,9 +22,7 @@ import ./make-test-python.nix ({ lib, pkgs, ... }: {
       ensureUsers = [
         {
           name = "freshrss";
-          ensurePermissions = {
-            "DATABASE freshrss" = "ALL PRIVILEGES";
-          };
+          ensureDBOwnership = true;
         }
       ];
       initialScript = pkgs.writeText "postgresql-password" ''
diff --git a/nixos/tests/grafana/basic.nix b/nixos/tests/grafana/basic.nix
index 8bf4caad7fbf..dd389bc8a3d1 100644
--- a/nixos/tests/grafana/basic.nix
+++ b/nixos/tests/grafana/basic.nix
@@ -55,7 +55,7 @@ let
         ensureDatabases = [ "grafana" ];
         ensureUsers = [{
           name = "grafana";
-          ensurePermissions."DATABASE grafana" = "ALL PRIVILEGES";
+          ensureDBOwnership = true;
         }];
       };
       systemd.services.grafana.after = [ "postgresql.service" ];
diff --git a/nixos/tests/hockeypuck.nix b/nixos/tests/hockeypuck.nix
index 2b9dba8720ab..675d6b226ad2 100644
--- a/nixos/tests/hockeypuck.nix
+++ b/nixos/tests/hockeypuck.nix
@@ -35,7 +35,7 @@ in {
       ensureDatabases = [ "hockeypuck" ];
       ensureUsers = [{
         name = "hockeypuck";
-        ensurePermissions."DATABASE hockeypuck" = "ALL PRIVILEGES";
+        ensureDBOwnership = true;
       }];
     };
   };
diff --git a/nixos/tests/home-assistant.nix b/nixos/tests/home-assistant.nix
index e97e8a467b18..e1588088ba19 100644
--- a/nixos/tests/home-assistant.nix
+++ b/nixos/tests/home-assistant.nix
@@ -9,13 +9,11 @@ in {
   nodes.hass = { pkgs, ... }: {
     services.postgresql = {
       enable = true;
-
-      # FIXME: hack for https://github.com/NixOS/nixpkgs/issues/216989
-      # Should be replaced with ensureUsers again when a solution for that is found
-      initialScript = pkgs.writeText "hass-setup-db.sql" ''
-        CREATE ROLE hass WITH LOGIN;
-        CREATE DATABASE hass WITH OWNER hass;
-      '';
+      ensureDatabases = [ "hass" ];
+      ensureUsers = [{
+        name = "hass";
+        ensureDBOwnership = true;
+      }];
     };
 
     services.home-assistant = {
diff --git a/nixos/tests/paperless.nix b/nixos/tests/paperless.nix
index 22409e899236..6a51cc522bdc 100644
--- a/nixos/tests/paperless.nix
+++ b/nixos/tests/paperless.nix
@@ -17,7 +17,7 @@ import ./make-test-python.nix ({ lib, ... }: {
         ensureDatabases = [ "paperless" ];
         ensureUsers = [
           { name = config.services.paperless.user;
-            ensurePermissions = { "DATABASE \"paperless\"" = "ALL PRIVILEGES"; };
+            ensureDBOwnership = true;
           }
         ];
       };
diff --git a/nixos/tests/pgadmin4.nix b/nixos/tests/pgadmin4.nix
index cb8de87c9ee3..3ee7ed19fa1c 100644
--- a/nixos/tests/pgadmin4.nix
+++ b/nixos/tests/pgadmin4.nix
@@ -19,14 +19,6 @@ import ./make-test-python.nix ({ pkgs, lib, ... }:
       authentication = ''
         host    all             all             localhost               trust
       '';
-      ensureUsers = [
-        {
-          name = "postgres";
-          ensurePermissions = {
-            "DATABASE \"postgres\"" = "ALL PRIVILEGES";
-          };
-        }
-      ];
     };
 
     services.pgadmin = {
diff --git a/nixos/tests/pgbouncer.nix b/nixos/tests/pgbouncer.nix
index 1e72327d4200..814ca0d58865 100644
--- a/nixos/tests/pgbouncer.nix
+++ b/nixos/tests/pgbouncer.nix
@@ -24,13 +24,11 @@ in
       services = {
         postgresql = {
           enable = true;
-          ensureDatabases = [ "testdb" ];
+          ensureDatabases = [ "test" ];
           ensureUsers = [
           {
-            name = "testuser";
-            ensurePermissions = {
-              "DATABASE testdb" = "ALL PRIVILEGES";
-            };
+            name = "test";
+            ensureDBOwnership = true;
           }];
           authentication = ''
             local testdb testuser scram-sha-256
@@ -40,7 +38,7 @@ in
         pgbouncer = {
           enable = true;
           listenAddress = "localhost";
-          databases = { testdb = "host=/run/postgresql/ port=5432 auth_user=testuser dbname=testdb"; };
+          databases = { test = "host=/run/postgresql/ port=5432 auth_user=testuser dbname=test"; };
           authType = "scram-sha-256";
           authFile = testAuthFile;
         };
@@ -55,7 +53,7 @@ in
 
     # Test if we can make a query through PgBouncer
     one.wait_until_succeeds(
-        "psql 'postgres://testuser:testpass@localhost:6432/testdb' -c 'SELECT 1;'"
+        "psql 'postgres://testuser:testpass@localhost:6432/test' -c 'SELECT 1;'"
     )
   '';
 })
diff --git a/nixos/tests/powerdns-admin.nix b/nixos/tests/powerdns-admin.nix
index d7bacb24eec5..d326d74a9826 100644
--- a/nixos/tests/powerdns-admin.nix
+++ b/nixos/tests/powerdns-admin.nix
@@ -87,9 +87,7 @@ let
           ensureUsers = [
             {
               name = "powerdnsadmin";
-              ensurePermissions = {
-                "DATABASE powerdnsadmin" = "ALL PRIVILEGES";
-              };
+              ensureDBOwnership = true;
             }
           ];
         };
diff --git a/nixos/tests/sftpgo.nix b/nixos/tests/sftpgo.nix
index db0098d2ac48..a5bb1981d2c3 100644
--- a/nixos/tests/sftpgo.nix
+++ b/nixos/tests/sftpgo.nix
@@ -156,7 +156,7 @@ in
         ensureDatabases = [ "sftpgo" ];
         ensureUsers = [{
           name = "sftpgo";
-          ensurePermissions."DATABASE sftpgo" = "ALL PRIVILEGES";
+          ensureDBOwnership = true;
         }];
       };
 
diff --git a/nixos/tests/tandoor-recipes.nix b/nixos/tests/tandoor-recipes.nix
index f3369da99a05..18beaac6f062 100644
--- a/nixos/tests/tandoor-recipes.nix
+++ b/nixos/tests/tandoor-recipes.nix
@@ -5,6 +5,29 @@ import ./make-test-python.nix ({ lib, ... }: {
   nodes.machine = { pkgs, ... }: {
     services.tandoor-recipes = {
       enable = true;
+      extraConfig = {
+        DB_ENGINE = "django.db.backends.postgresql";
+        POSTGRES_HOST = "/run/postgresql";
+        POSTGRES_USER = "tandoor_recipes";
+        POSTGRES_DB = "tandoor_recipes";
+      };
+    };
+
+    services.postgresql = {
+      enable = true;
+      ensureDatabases = [ "tandoor_recipes" ];
+      ensureUsers = [
+        {
+          name = "tandoor_recipes";
+          ensureDBOwnership = true;
+        }
+      ];
+    };
+
+    systemd.services = {
+      tandoor-recipes = {
+        after = [ "postgresql.service" ];
+      };
     };
   };
 
diff --git a/nixos/tests/vikunja.nix b/nixos/tests/vikunja.nix
index 2660aa9767ca..60fd5ce13854 100644
--- a/nixos/tests/vikunja.nix
+++ b/nixos/tests/vikunja.nix
@@ -33,7 +33,7 @@ import ./make-test-python.nix ({ pkgs, lib, ... }: {
         ensureDatabases = [ "vikunja-api" ];
         ensureUsers = [
           { name = "vikunja-api";
-            ensurePermissions = { "DATABASE \"vikunja-api\"" = "ALL PRIVILEGES"; };
+            ensureDBOwnership = true;
           }
         ];
       };
diff --git a/nixos/tests/wiki-js.nix b/nixos/tests/wiki-js.nix
index fd054a9c5909..8b3c51935a6c 100644
--- a/nixos/tests/wiki-js.nix
+++ b/nixos/tests/wiki-js.nix
@@ -10,14 +10,15 @@ import ./make-test-python.nix ({ pkgs, lib, ...} : {
       enable = true;
       settings.db.host = "/run/postgresql";
       settings.db.user = "wiki-js";
+      settings.db.db = "wiki-js";
       settings.logLevel = "debug";
     };
     services.postgresql = {
       enable = true;
-      ensureDatabases = [ "wiki" ];
+      ensureDatabases = [ "wiki-js" ];
       ensureUsers = [
         { name = "wiki-js";
-          ensurePermissions."DATABASE wiki" = "ALL PRIVILEGES";
+          ensureDBOwnership = true;
         }
       ];
     };