Merge pull request #42153 from Ekleog/opensmtpd-changeable-package

opensmtpd module: allow changing the package

nixos/modules/services/mail/opensmtpd.nix

···
 
   sendmail = pkgs.runCommand "opensmtpd-sendmail" {} ''
     mkdir -p $out/bin
-    ln -s ${pkgs.opensmtpd}/sbin/smtpctl $out/bin/sendmail
+    ln -s ${cfg.package}/sbin/smtpctl $out/bin/sendmail
   '';
 
 in {
···
         type = types.bool;
         default = false;
         description = "Whether to enable the OpenSMTPD server.";
+      };
+
+      package = mkOption {
+        type = types.package;
+        default = pkgs.opensmtpd;
+        defaultText = "pkgs.opensmtpd";
+        description = "The OpenSMTPD package to use.";
       };
 
       addSendmailToSystemPath = mkOption {
···
     systemd.services.opensmtpd = let
       procEnv = pkgs.buildEnv {
         name = "opensmtpd-procs";
-        paths = [ pkgs.opensmtpd ] ++ cfg.procPackages;
+        paths = [ cfg.package ] ++ cfg.procPackages;
         pathsToLink = [ "/libexec/opensmtpd" ];
       };
     in {
···
         chown smtpq.root /var/spool/smtpd/purge
         chmod 700 /var/spool/smtpd/purge
       '';
-      serviceConfig.ExecStart = "${pkgs.opensmtpd}/sbin/smtpd -d -f ${conf} ${args}";
+      serviceConfig.ExecStart = "${cfg.package}/sbin/smtpd -d -f ${conf} ${args}";
       environment.OPENSMTPD_PROC_PATH = "${procEnv}/libexec/opensmtpd";
     };