From f62c283bedd6c74cbaf091c5b94a1ca81883998e Mon Sep 17 00:00:00 2001
From: Benjamin Hamon <development@benjaminhamon.com>
Date: Sat, 14 Mar 2026 17:17:39 +0100
Subject: [PATCH] Fix metrics for gunicorn

---
 Deployment/application.json                     |  1 +
 Deployment/dockerfile                           |  6 +++++-
 Deployment/gunicorn_configuration.py            |  6 ++++++
 .../application_factory.py                      | 17 +++++++++++++----
 .../wsgi_entry_point.py                         |  3 ++-
 5 files changed, 27 insertions(+), 6 deletions(-)

diff --git a/Deployment/application.json b/Deployment/application.json
index 703d972..2f8dd71 100644
--- a/Deployment/application.json
+++ b/Deployment/application.json
@@ -1,3 +1,4 @@
 {
+	"server": "gunicorn",
 	"metrics_token": "metrics"
 }
diff --git a/Deployment/dockerfile b/Deployment/dockerfile
index 809f312..3cfbca1 100644
--- a/Deployment/dockerfile
+++ b/Deployment/dockerfile
@@ -1,4 +1,4 @@
-# cspell:words a2enmod gunicorn libapache2 venv virtualenv wsgi
+# cspell:words gunicorn venv
 
 FROM debian:12
 
@@ -18,6 +18,10 @@ COPY pip.conf /srv/application/.venv/pip.conf
 # Install the application and gunicorn
 RUN /srv/application/.venv/bin/python -m pip install --upgrade /srv/application/website "gunicorn ~= 23.0.0"
 
+# Configure directory for prometheus metrics
+RUN mkdir --parents /srv/prometheus
+ENV PROMETHEUS_MULTIPROC_DIR=/srv/prometheus
+
 
 
 # Open network port
diff --git a/Deployment/gunicorn_configuration.py b/Deployment/gunicorn_configuration.py
index fdb330a..90f9e1d 100644
--- a/Deployment/gunicorn_configuration.py
+++ b/Deployment/gunicorn_configuration.py
@@ -2,6 +2,8 @@
 
 import multiprocessing
 
+from prometheus_flask_exporter.multiprocess import GunicornInternalPrometheusMetrics
+
 from benjaminhamon_standard_extensions.logging import logging_helpers
 
 
@@ -41,3 +43,7 @@
 	    }
 	}
 }
+
+
+def child_exit(server, worker): # pylint: disable = unused-argument
+    GunicornInternalPrometheusMetrics.mark_process_dead_on_child_exit(worker.pid)
diff --git a/Sources/website/benjaminhamon_developer_website/application_factory.py b/Sources/website/benjaminhamon_developer_website/application_factory.py
index eeb7e45..aee278b 100644
--- a/Sources/website/benjaminhamon_developer_website/application_factory.py
+++ b/Sources/website/benjaminhamon_developer_website/application_factory.py
@@ -2,12 +2,13 @@
 
 import functools
 import logging
-from typing import Callable, List
+from typing import Callable, List, Optional
 
 import flask
 import jinja2
-import prometheus_flask_exporter
 import werkzeug.exceptions
+from prometheus_flask_exporter import PrometheusMetrics
+from prometheus_flask_exporter.multiprocess import GunicornInternalPrometheusMetrics
 
 import benjaminhamon_developer_website
 from benjaminhamon_developer_website.application import Application
@@ -18,13 +19,13 @@
 request_logger = logging.getLogger("Request")
 
 
-def create_application(metrics_token: str) -> Application:
+def create_application(metrics_token: str, server: Optional[str] = None) -> Application:
     flask_application = flask.Flask("benjaminhamon_developer_website")
     flask_application.config.update(
         METRICS_TOKEN = metrics_token,
     )
 
-    prometheus_metrics = prometheus_flask_exporter.PrometheusMetrics(None, metrics_decorator = metrics_authorization)
+    prometheus_metrics = create_metrics(server)
     application = Application(flask_application)
     main_controller = MainController()
 
@@ -36,6 +37,14 @@ def create_application(metrics_token: str) -> Application:
     return application
 
 
+def create_metrics(server: Optional[str] = None) -> PrometheusMetrics:
+    if server is None:
+        return PrometheusMetrics(None, metrics_decorator = metrics_authorization)
+    if server == "gunicorn":
+        return GunicornInternalPrometheusMetrics(None, metrics_decorator = metrics_authorization)
+    raise ValueError("Unsupported server: '%s'" % server)
+
+
 def configure(application: flask.Flask) -> None:
     application.config["METADATA"] = {
         "product": benjaminhamon_developer_website.__product__,
diff --git a/Sources/website/benjaminhamon_developer_website/wsgi_entry_point.py b/Sources/website/benjaminhamon_developer_website/wsgi_entry_point.py
index 3b81ffa..903be7a 100644
--- a/Sources/website/benjaminhamon_developer_website/wsgi_entry_point.py
+++ b/Sources/website/benjaminhamon_developer_website/wsgi_entry_point.py
@@ -15,4 +15,5 @@
     configuration = json.load(configuration_file)
 
 application = application_factory.create_application(
-    metrics_token = configuration["metrics_token"])
+    metrics_token = configuration["metrics_token"],
+    server = configuration["server"])