*arr: fix (?)

2026-05-04 20:25:04 -04:00
parent a95f614dd9
commit 9ef9389672
3 changed files with 99 additions and 0 deletions
--- a/lib/default.nix
+++ b/lib/default.nix
@@ -285,5 +285,84 @@ lib.extend (
    # Returns a string suitable for $() command substitution in shell scripts.
    extractArrApiKey =
      configXmlPath: "${lib.getExe pkgs.gnugrep} -oP '(?<=<ApiKey>)[^<]+' ${configXmlPath}";
+
+    # Creates a NixOS-managed *arr settings sync service.
+    # Spawns a oneshot systemd unit that PUTs the requested values into the *arr API
+    # whenever the *arr service starts (or when the desired settings change). The
+    # API key is read from the *arr's own config.xml at runtime.
+    #
+    # `settings` is keyed by API endpoint under /api/v3/config/, with one nested
+    # attrset of field-name -> value pairs per endpoint. Idempotent: it skips the
+    # PUT when the live config already matches.
+    mkArrSettingsService =
+      {
+        name,
+        port,
+        dataDir,
+        settings,
+      }:
+      { pkgs, config, ... }:
+      let
+        configXml = "${dataDir}/config.xml";
+        endpoints = lib.attrNames settings;
+        applyOne =
+          endpoint:
+          let
+            jqFilter = lib.concatStringsSep " | " (
+              lib.mapAttrsToList (k: v: ".${k} = ${builtins.toJSON v}") settings.${endpoint}
+            );
+          in
+          ''
+            echo ":: ${name} config/${endpoint}"
+            CFG=$(curl -fsS -H "X-Api-Key: $KEY" "$BASE/config/${endpoint}")
+            NEW=$(jq '${jqFilter}' <<<"$CFG")
+            if [ "$CFG" = "$NEW" ]; then
+              echo "  unchanged"
+            else
+              ID=$(jq -r .id <<<"$NEW")
+              curl -fsS -X PUT \
+                -H "X-Api-Key: $KEY" -H "Content-Type: application/json" \
+                --data "$NEW" "$BASE/config/${endpoint}/$ID" >/dev/null
+              echo ${final.escapeShellArg "  applied: ${jqFilter}"}
+            fi
+          '';
+        applyScript = pkgs.writeShellApplication {
+          name = "${name}-apply-settings";
+          runtimeInputs = with pkgs; [
+            curl
+            jq
+            gnugrep
+          ];
+          text = ''
+            set -euo pipefail
+            KEY=$(grep -oP '(?<=<ApiKey>)[^<]+' ${configXml})
+            BASE="http://localhost:${toString port}/api/v3"
+
+            # Wait up to 60s for the API to come online.
+            for _ in $(seq 1 30); do
+              if curl -fsS --max-time 2 -H "X-Api-Key: $KEY" "$BASE/system/status" >/dev/null 2>&1; then
+                break
+              fi
+              sleep 2
+            done
+
+            ${lib.concatStringsSep "\n" (map applyOne endpoints)}
+          '';
+        };
+      in
+      {
+        systemd.services."${name}-apply-settings" = {
+          description = "Apply NixOS-managed ${name} settings via API";
+          after = [ "${name}.service" ];
+          wantedBy = [ "${name}.service" ];
+          restartTriggers = [ applyScript ];
+          serviceConfig = {
+            Type = "oneshot";
+            User = config.services.${name}.user;
+            Group = config.services.${name}.group;
+            ExecStart = lib.getExe applyScript;
+          };
+        };
+      };
  }
 )