remove Diffie Hillman parameter creation as it is handled by the upstream dovecot2 module as of 18.09

default.nix

@@ -405,17 +405,6 @@ in
       '';
     };
 
-    dhParamBitLength = mkOption {
-      type = types.int;
-      default = 2048;
-      description =
-        ''
-        Length of the Diffie Hillman prime used (in bits). It might be a good
-        idea to set this to 4096 for security purposed, but it will take a _very_
-        long time to create this prime on startup.
-        '';
-    };
-
     debug = mkOption {
       type = types.bool;
       default = false;

mail-server/dovecot.nix

@@ -97,9 +97,6 @@ in
 
         mail_access_groups = ${vmailGroupName}
         ssl = required
-        ${lib.optionalString (lib.versionAtLeast (lib.getVersion pkgs.dovecot) "2.3") ''
-          ssl_dh = <${certificateDirectory}/dh.pem
-        ''}
 
         service lmtp {
           unix_listener dovecot-lmtp {

mail-server/systemd.nix

@@ -18,20 +18,6 @@
 
 let
   cfg = config.mailserver;
-
-  createDhParameterFile =
-    lib.optionalString (lib.versionAtLeast (lib.getVersion pkgs.dovecot) "2.3")
-      ''
-        # Create a dh parameter file
-        if [ ! -s "${cfg.certificateDirectory}/dh.pem" ]
-        then
-            mkdir -p "${cfg.certificateDirectory}"
-            ${pkgs.openssl}/bin/openssl \
-                  dhparam ${builtins.toString cfg.dhParamBitLength} \
-                  > "${cfg.certificateDirectory}/dh.pem"
-        fi
-      '';
-
   preliminarySelfsigned = config.security.acme.preliminarySelfsigned;
   acmeWantsTarget = [ "acme-certificates.target" ]
     ++ (lib.optional preliminarySelfsigned "acme-selfsigned-certificates.target");
@@ -74,7 +60,7 @@ in
       };
     };
 
-    # Create maildir folder and dh parameters before dovecot startup
+    # Create maildir folder before dovecot startup
     systemd.services.dovecot2 = {
       after = [ "mailserver-certificates.target" ];
       wants = [ "mailserver-certificates.target" ];
@@ -84,8 +70,6 @@ in
         mkdir -p "${mailDirectory}"
         chgrp "${vmailGroupName}" "${mailDirectory}"
         chmod 02770 "${mailDirectory}"
-
-        ${createDhParameterFile}
       '';
     };
 

tests/clamav.nix

@@ -71,7 +71,6 @@ import <nixpkgs/nixos/tests/make-test.nix> {
               debug = true;
               fqdn = "mail.example.com";
               domains = [ "example.com" "example2.com" ];
-              dhParamBitLength = 512;
               virusScanning = true;
 
               loginAccounts = {

tests/extern.nix

@@ -36,7 +36,6 @@ import <nixpkgs/nixos/tests/make-test.nix> {
               debug = true;
               fqdn = "mail.example.com";
               domains = [ "example.com" "example2.com" ];
-              dhParamBitLength = 512;
               rewriteMessageId = true;
 
               loginAccounts = {

tests/intern.nix

@@ -27,7 +27,6 @@ import <nixpkgs/nixos/tests/make-test.nix> {
           enable = true;
           fqdn = "mail.example.com";
           domains = [ "example.com" ];
-          dhParamBitLength = 512;
 
           loginAccounts = {
               "user1@example.com" = {