Add PostgreSQL DB for performance tests results

The database will hold the performance results of the execution of the
benchmarks. We follow the same setup on knights3 for now.

m/hut/configuration.nix

@@ -15,6 +15,7 @@
     ./public-inbox.nix
     ./gitea.nix
     ./msmtp.nix
+    ./postgresql.nix
     #./pxe.nix
   ];
 

m/hut/postgresql.nix

@@ -0,0 +1,19 @@
+{ lib, ... }:
+
+{
+  services.postgresql = {
+    enable = true;
+    ensureDatabases = [ "perftestsdb" ];
+    ensureUsers = [
+      { name = "anavarro"; ensureClauses.superuser = true; }
+      { name = "rarias";   ensureClauses.superuser = true; }
+      { name = "grafana"; }
+    ];
+    authentication = ''
+      #type  database     DBuser    auth-method
+      local  perftestsdb  rarias    trust
+      local  perftestsdb  anavarro  trust
+      local  perftestsdb  grafana   trust
+    '';
+  };
+}