Allow metrics in debug mode with DEBUG_METRICS

.travis.yml

@@ -28,18 +28,22 @@ script:
 
 jobs:
   include:
-  - stage: wsgi
+  - stage: integration
     sudo: true
     script:
       - sh examples/gunicorn/run_tests.sh
-  - stage: wsgi
+  - stage: integration
     sudo: true
     script:
       - sh examples/uwsgi/run_tests.sh
-  - stage: wsgi
+  - stage: integration
     sudo: true
     script:
       - sh examples/wsgi/run_tests.sh
+  - stage: integration
+    sudo: true
+    script:
+      - sh examples/reload/run_tests.sh
 
   - stage: deploy
     script: skip

README.md

@@ -160,6 +160,12 @@ app with `debug=True`, are not going to be reflected in the metrics.
 See [https://github.com/rycus86/prometheus_flask_exporter/issues/4](https://github.com/rycus86/prometheus_flask_exporter/issues/4)
 for more details.
 
+Alternatively - since version 0.5.1 -, if you set the `DEBUG_METRICS`
+environment variable, you will get metrics for the latest reloaded code.
+These will be exported on the main Flask app, serving the metrics on
+a different port is not going to work most probably - e.g.
+`PrometheusMetrics.start_http_server(..)` is not expected to work.
+
 ## WSGI
 
 Getting accurate metrics for WSGI apps might require a bit more setup.

examples/reload/Dockerfile

@@ -0,0 +1,13 @@
+FROM python:3.7-alpine
+
+RUN apk add --no-cache curl && pip install flask prometheus_client
+
+ADD . /tmp/latest
+RUN pip install -e /tmp/latest --upgrade
+
+ADD examples/reload/reload_example.py /var/flask/example.py
+WORKDIR /var/flask
+
+ENV DEBUG_METRICS 1
+
+CMD python /var/flask/example.py

examples/reload/reload_example.py

@@ -0,0 +1,20 @@
+from flask import Flask
+from prometheus_flask_exporter import PrometheusMetrics
+
+app = Flask(__name__)
+metrics = PrometheusMetrics(app)
+
+
+@app.route('/test')
+def index():
+    return 'Hello world'
+
+
+@app.route('/ping')
+@metrics.do_not_track()
+def ping():
+    return 'pong'
+
+
+if __name__ == '__main__':
+    app.run('0.0.0.0', 4000, debug=True)

examples/reload/run_tests.sh

@@ -0,0 +1,76 @@
+#!/bin/bash
+
+cd "$(dirname "$0")"
+
+_fail() {
+    docker rm -f reload-sample > /dev/null 2>&1
+    exit 1
+}
+
+docker build -f Dockerfile -t reload-sample ../../. > /dev/null || _fail
+docker run -d --name reload-sample -p 4000:4000 reload-sample > /dev/null || _fail
+
+echo 'Waiting for the server to start...'
+
+for _ in $(seq 1 10); do
+    if curl -fs http://localhost:4000/ping > /dev/null; then
+        break
+    else
+        sleep 0.2
+    fi
+done
+
+echo 'Starting the initial tests...'
+
+for _ in $(seq 1 10); do
+    curl -s http://localhost:4000/test > /dev/null
+    if [ "$?" != "0" ]; then
+        echo 'Failed to request the test endpoint'
+        _fail
+    fi
+done
+
+curl -s http://localhost:4000/metrics \
+  | grep 'flask_http_request_duration_seconds_count{method="GET",path="/test",status="200"} 10.0' \
+  > /dev/null
+
+if [ "$?" != "0" ]; then
+    echo 'The expected metrics are not found'
+    _fail
+fi
+
+echo 'Changing the server...'
+docker exec -it reload-sample sed -i "s#@app.route('/test')#@app.route('/changed')#" /var/flask/example.py
+docker exec -it reload-sample sed -i "s#@app.route('/ping')#@app.route('/ping2')#" /var/flask/example.py
+
+echo 'Waiting for the server to apply the changes...'
+
+for _ in $(seq 1 10); do
+    if curl -fs http://localhost:4000/ping2 > /dev/null; then
+        break
+    else
+        sleep 0.2
+    fi
+done
+
+echo 'Starting the changed tests...'
+
+for _ in $(seq 1 12); do
+    curl -s http://localhost:4000/changed > /dev/null
+    if [ "$?" != "0" ]; then
+        echo 'Failed to request the test endpoint'
+        _fail
+    fi
+done
+
+curl -s http://localhost:4000/metrics \
+  | grep 'flask_http_request_duration_seconds_count{method="GET",path="/changed",status="200"} 12.0' \
+  > /dev/null
+
+if [ "$?" != "0" ]; then
+    echo 'The expected metrics are not found'
+    _fail
+fi
+
+docker rm -f reload-sample > /dev/null
+echo 'OK, all done'

prometheus_flask_exporter/__init__.py

@@ -146,7 +146,7 @@ def register_endpoint(self, path, app=None):
             (by default it is the application registered with this class)
         """
 
-        if is_running_from_reloader():
+        if is_running_from_reloader() and not os.environ.get('DEBUG_METRICS'):
             return
 
         if app is None:
@@ -522,4 +522,4 @@ def info(self, name, description, labelnames=None, labelvalues=None, **labels):
         return gauge
 
 
-__version__ = '0.5.0'
+__version__ = '0.5.1'

setup.py

@@ -6,15 +6,15 @@
 setup(
     name='prometheus_flask_exporter',
     packages=['prometheus_flask_exporter'],
-    version='0.5.0',
+    version='0.5.1',
     description='Prometheus metrics exporter for Flask',
     long_description=long_description,
     long_description_content_type='text/markdown',
     license='MIT',
     author='Viktor Adam',
     author_email='rycus86@gmail.com',
     url='https://github.com/rycus86/prometheus_flask_exporter',
-    download_url='https://github.com/rycus86/prometheus_flask_exporter/archive/0.5.0.tar.gz',
+    download_url='https://github.com/rycus86/prometheus_flask_exporter/archive/0.5.1.tar.gz',
     keywords=['prometheus', 'flask', 'monitoring', 'exporter'],
     classifiers=[
         'Development Status :: 4 - Beta',