nixos/simp_le: improve configuration options

nixos/modules/services/security/simp_le.nix

@@ -9,9 +9,14 @@ let
   certOpts = { ... }: {
     options = {
       webroot = mkOption {
-        type = types.nullOr types.str;
-        default = null;
-        description = "Where the webroot of the HTTP vhost is located.";
+        type = types.str;
+        description = ''
+          Where the webroot of the HTTP vhost is located.
+          <filename>.well-known/acme-challenge/</filename> directory
+          will be created automatically if it doesn't exist.
+          <literal>http://example.org/.well-known/acme-challenge/</literal> must also
+          be available (notice unencrypted HTTP).
+        '';
       };
 
       validMin = mkOption {
@@ -32,20 +37,53 @@ let
         description = "Contact email address for the CA to be able to reach you.";
       };
 
+      user = mkOption {
+        type = types.str;
+        default = "root";
+        description = "User under which simp_le would run.";
+      };
+
+      group = mkOption {
+        type = types.str;
+        default = "root";
+        description = "Group under which simp_le would run.";
+      };
+
+      postRun = mkOption {
+        type = types.lines;
+        default = "";
+        example = "systemctl reload nginx.service";
+        description = ''
+          Commands to run after certificates are re-issued. Typically
+          the web server and other servers using certificates need to
+          be reloaded.
+        '';
+      };
+
       plugins = mkOption {
         type = types.listOf (types.enum [
           "cert.der" "cert.pem" "chain.der" "chain.pem" "external_pem.sh"
-          "fullchain.der" "fullchain.pem" "key.der" "key.pem"
+          "fullchain.der" "fullchain.pem" "key.der" "key.pem" "account_key.json"
         ]);
-        default = [ "fullchain.pem" "key.pem" ];
-        description = "Plugins to enable.";
+        default = [ "fullchain.pem" "key.pem" "account_key.json" ];
+        description = ''
+          Plugins to enable. With default settings simp_le will
+          store public certificate bundle in <filename>fullchain.pem</filename>
+          and private key in <filename>key.pem</filename> in its state directory.
+        '';
       };
 
       extraDomains = mkOption {
-        default = [ ];
-        type = types.listOf types.str;
-        description = "More domains to include in the certificate.";
-        example = [ "example.com" "foo.example.com:/var/www/foo" ];
+        type = types.attrsOf (types.nullOr types.str);
+        default = {};
+        example = {
+          "example.org" = "/srv/http/nginx";
+          "mydomain.org" = null;
+        };
+        description = ''
+          Extra domain names for which certificates are to be issued, with their
+          own server roots if needed.
+        '';
       };
     };
   };
@@ -62,7 +100,7 @@ in
         default = "/etc/ssl";
         type = types.str;
         description = ''
-          Directory where certs will be stored by default.
+          Directory where certs and other state will be stored by default.
         '';
       };
 
@@ -74,10 +112,10 @@ in
         '';
         options = [ certOpts ];
         example = {
-          "foo.example.com" = {
+          "example.com" = {
             webroot = "/var/www/challenges/";
             email = "foo@example.com";
-            extraDomains = [ "www.example.com" "example.com" ];
+            extraDomains = { "www.example.com" = null; "foo.example.com" = "/var/www/foo/"; };
           };
           "bar.example.com" = {
             webroot = "/var/www/challenges/";
@@ -91,27 +129,42 @@ in
   ###### implementation
   config = mkIf (cfg.certs != { }) {
 
-    systemd.services = flip mapAttrs' cfg.certs (cert: data: nameValuePair
+    systemd.services = flip mapAttrs' cfg.certs (cert: data:
+      let
+        cpath = "${cfg.directory}/${cert}";
+        cmdline = [ "-v" "-d" cert "--default_root" data.webroot "--valid_min" data.validMin ]
+                  ++ optionals (data.email != null) [ "--email" data.email ]
+                  ++ concatMap (p: [ "-f" p ]) data.plugins
+                  ++ concatLists (mapAttrsToList (name: root: [ "-d" (if root == null then name else "${name}:${root}")]) data.extraDomains);
+
+      in nameValuePair
       ("simp_le-${cert}")
       ({
         description = "simp_le cert renewal for ${cert}";
         after = [ "network.target" ];
         serviceConfig = {
           Type = "oneshot";
-          SuccessExitStatus = "0 1";
+          SuccessExitStatus = [ "0" "1" ];
         };
+        path = [ pkgs.simp_le pkgs.sudo ];
         preStart = ''
-          mkdir -p "${cfg.directory}/${cert}"
+          mkdir -p '${cfg.directory}'
+          if [ ! -d '${cpath}' ]; then
+            mkdir -m 700 '${cpath}'
+            chown '${data.user}:${data.group}' '${cpath}'
+          fi
         '';
         script = ''
-          WEBROOT="${optionalString (data.webroot == null) data.webroot}"
-          cd "${cfg.directory}/${cert}"
-          ${pkgs.simp_le}/bin/simp_le -v \
-            ${concatMapStringsSep " " (p: "-f ${p}") data.plugins} \
-            -d ${cert} --default_root "$WEBROOT" \
-            ${concatMapStringsSep " " (p: "-d ${p}") data.extraDomains} \
-            ${optionalString (data.email != null) "--email ${data.email}"} \
-            --valid_min ${toString data.validMin}
+          cd '${cpath}'
+          set +e
+          sudo -u '${data.user}' -- simp_le ${concatMapStringsSep " " (arg: escapeShellArg (toString arg)) cmdline}
+          EXITCODE=$?
+          set -e
+          if [ "$EXITCODE" = "0" ]; then
+            ${data.postRun}
+          else
+            exit "$EXITCODE"
+          fi
         '';
       })
     );