tv.urlwatch: init

modules/tv/urlwatch/default.nix

@@ -0,0 +1,158 @@
+{ config, lib, pkgs, ... }:
+
+# TODO multiple users
+# TODO inform about unused caches
+# cache = url: "${cfg.dataDir}/.urlwatch/cache/${hashString "sha1" url}"
+# TODO hooks.py
+
+let
+  inherit (builtins) toFile;
+  inherit (lib)
+    concatStringsSep escapeShellArg mkIf mkOption optionals singleton types;
+  inherit (pkgs) writeScript;
+
+  cfg = config.tv.urlwatch;
+
+  api = {
+    dataDir = mkOption {
+      type = types.str;
+      default = "/var/lib/urlwatch";
+      description = ''
+        Directory where the urlwatch service should store its state.
+      '';
+    };
+    enable = mkOption {
+      type = types.bool;
+      default = false;
+      description = ''
+        Whether to enable the urlwatch service.
+        If enabled, then create a timer that calls urlwatch and sends mails
+        whenever something has changed or an error occurs.
+      '';
+    };
+    from = mkOption {
+      type = types.str;
+      default = "${cfg.user}@${config.networking.hostName}.retiolum";
+      description = ''
+        Content of the From: header of the generated mails.
+      '';
+    };
+    mailto = mkOption {
+      type = types.str;
+      description = ''
+        Content of the To: header of the generated mails. [AKA recipient :)]
+      '';
+    };
+    onCalendar = mkOption {
+      type = types.str;
+      description = ''
+        Run urlwatch at this interval.
+        The format is described in systemd.time(7), CALENDAR EVENTS.
+      '';
+      example = "04:23";
+    };
+    urls = mkOption {
+      type = with types; listOf str;
+      description = "URL to watch.";
+      example = [
+        https://nixos.org/channels/nixos-unstable/git-revision
+      ];
+    };
+    user = mkOption {
+      type = types.str;
+      default = "urlwatch";
+      description = "User under which urlwatch runs.";
+    };
+  };
+
+  urlsFile = toFile "urls" (concatStringsSep "\n" cfg.urls);
+
+  impl = {
+    systemd.timers.urlwatch = {
+      wantedBy = [ "timers.target" ];
+      timerConfig = {
+        OnCalendar = cfg.onCalendar;
+        Persistent = "true";
+      };
+    };
+    systemd.services.urlwatch = {
+      path = with pkgs; [
+        coreutils
+        gnused
+        urlwatch
+      ];
+      environment = {
+        HOME = cfg.dataDir;
+        LC_ALL = "en_US.UTF-8";
+        LOCALE_ARCHIVE = "${pkgs.glibcLocales}/lib/locale/locale-archive";
+        SSL_CERT_FILE = "${pkgs.cacert}/etc/ssl/certs/ca-bundle.crt";
+      };
+      serviceConfig = {
+        User = cfg.user;
+        PermissionsStartOnly = "true";
+        PrivateTmp = "true";
+        Type = "oneshot";
+        ExecStartPre =
+          writeScript "urlwatch-prestart" ''
+            #! /bin/sh
+            set -euf
+
+            dataDir=$HOME
+            user=${escapeShellArg cfg.user}
+
+            if ! test -e "$dataDir"; then
+              mkdir -m 0700 -p "$dataDir"
+              chown "$user": "$dataDir"
+            fi
+          '';
+        ExecStart = writeScript "urlwatch" ''
+          #! /bin/sh
+          set -euf
+
+          from=${escapeShellArg cfg.from}
+          mailto=${escapeShellArg cfg.mailto}
+          urlsFile=${escapeShellArg urlsFile}
+          user=${escapeShellArg cfg.user}
+
+          cd /tmp
+
+          urlwatch -e --urls="$urlsFile" > changes 2>&1 || :
+
+          if test -s changes; then
+            date=$(date -R)
+            subject=$(sed -n 's/^\(CHANGED\|ERROR\|NEW\): //p' changes \
+              | tr \\n \ )
+            {
+              echo "Date: $date"
+              echo "From: $from"
+              echo "Subject: $subject"
+              echo "To: $mailto"
+              echo
+              cat changes
+            } | /var/setuid-wrappers/sendmail -t
+          fi
+        '';
+      };
+    };
+    users.extraUsers = optionals (cfg.user == "urlwatch") (singleton {
+      name = "urlwatch";
+      uid = 3450919516; # bin/genid urlwatch
+    });
+  };
+
+in
+
+{
+  # TODO
+  #imports = [
+  #  ./exim
+  #];
+  #config = mkIf cfg.enable
+  #  (if config.tv.exim.enable
+  #    then impl
+  #    else throw "tv.exim must be enabled when enabling tv.urlwatch");
+
+  options.tv.urlwatch = api;
+  
+  config = impl;
+}