common-config.journald: only store in-memory, max 100MB, maximum 1d

Clears all logs on reboot, clears data after 100MB or after 1day,
whatever comes first.

shared/applications/server/nginx.nix

@@ -22,6 +22,11 @@ in {
     # only allow PFS-enabled ciphers with AES256
     sslCiphers = "AES256+EECDH:AES256+EDH:!aNULL";
 
+    # disable access logs
+    commonHttpConfig= ''
+      access_log off;
+    '';
+
     # setup a default site
     virtualHosts.default = {
       default = lib.mkDefault true;

shared/base/common-config.nix

@@ -6,7 +6,13 @@
       settings.PasswordAuthentication = false;
     };
 
-    journald.extraConfig = "SystemMaxUse=100M";
+    journald = {
+      storage = "volatile";
+      extraConfig = ''
+        SystemMaxUse=100M
+        MaxRetentionSec=1d
+      '';
+    };
   };
 
   nix = {