diff --git a/Gemfile.lock b/Gemfile.lock
index 4a5f8f3b0..0c8af0fe8 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -110,8 +110,9 @@ GEM
     globalid (1.0.0)
       activesupport (>= 5.0)
     govuk_ab_testing (2.4.2)
-    govuk_app_config (4.3.0)
+    govuk_app_config (4.4.2)
       logstasher (>= 1.2.2, < 2.2.0)
+      prometheus_exporter (~> 2.0.2)
       puma (~> 5.0)
       sentry-rails (~> 4.5.0)
       sentry-ruby (~> 4.5.0)
@@ -204,6 +205,8 @@ GEM
       ast (~> 2.4.1)
     phantomjs (2.1.1.0)
     plek (4.0.0)
+    prometheus_exporter (2.0.2)
+      webrick
     pry (0.13.1)
       coderay (~> 1.1)
       method_source (~> 1.0)
@@ -360,6 +363,7 @@ GEM
       addressable (>= 2.3.6)
       crack (>= 0.3.2)
       hashdiff (>= 0.4.0, < 2.0.0)
+    webrick (1.7.0)
     websocket-driver (0.7.5)
       websocket-extensions (>= 0.1.0)
     websocket-extensions (0.1.5)