Add GDSMetrics package

As per instructions https://github.com/alphagov/gds_metrics_python

The celery workers don't have an HTTP endpoint so no point in trying to
get prometheus to scrape them.

app/__init__.py

@@ -7,6 +7,7 @@ from flask import _request_ctx_stack, request, g, jsonify, make_response
 from flask_sqlalchemy import SQLAlchemy as _SQLAlchemy
 from flask_marshmallow import Marshmallow
 from flask_migrate import Migrate
+from gds_metrics import GDSMetrics
 from time import monotonic
 from notifications_utils.clients.zendesk.zendesk_client import ZendeskClient
 from notifications_utils.clients.statsd.statsd_client import StatsdClient
@@ -54,6 +55,7 @@ statsd_client = StatsdClient()
 redis_store = RedisClient()
 performance_platform_client = PerformancePlatformClient()
 document_download_client = DocumentDownloadClient()
+metrics = GDSMetrics()
 
 clients = Clients()
 
@@ -86,6 +88,7 @@ def create_app(application):
     performance_platform_client.init_app(application)
     document_download_client.init_app(application)
     clients.init_app(sms_clients=[firetext_client, mmg_client], email_clients=[aws_ses_client])
+    metrics.init_app(application)
 
     register_blueprint(application)
     register_v2_blueprints(application)

gunicorn_config.py

@@ -3,6 +3,8 @@ import sys
 import traceback
 import gunicorn
 
+from gds_metrics.gunicorn import child_exit  # noqa
+
 workers = 4
 worker_class = "eventlet"
 worker_connections = 256

manifest.yml.j2

@@ -65,6 +65,9 @@ applications:
     services:
       - notify-db
       - logit-ssl-syslog-drain
+      {% if CF_APP == 'notify-api' %}
+      - notify-prometheus
+      {% endif %}
 
     env:
       NOTIFY_APP_NAME: {{ app.get('NOTIFY_APP_NAME', CF_APP.replace('notify-', '')) }}

requirements-app.txt

@@ -27,3 +27,5 @@ notifications-python-client==5.5.1
 awscli-cwlogs>=1.4,<1.5
 
 git+https://github.com/alphagov/notifications-utils.git@37.0.1#egg=notifications-utils==37.0.1
+
+gds-metrics==0.2.0

requirements.txt

@@ -30,18 +30,21 @@ awscli-cwlogs>=1.4,<1.5
 
 git+https://github.com/alphagov/notifications-utils.git@37.0.1#egg=notifications-utils==37.0.1
 
+gds-metrics==0.2.0
+
 ## The following requirements were added by pip freeze:
 alembic==1.4.2
 amqp==1.4.9
 anyjson==0.3.3
 attrs==19.3.0
-awscli==1.18.40
+awscli==1.18.41
 bcrypt==3.1.7
 billiard==3.3.0.23
 bleach==3.1.4
+blinker==1.4
 boto==2.49.0
 boto3==1.10.38
-botocore==1.15.40
+botocore==1.15.41
 certifi==2020.4.5.1
 chardet==3.0.4
 click==7.1.1
@@ -62,6 +65,7 @@ mistune==0.8.4
 monotonic==1.5
 orderedset==2.0.1
 phonenumbers==8.11.2
+prometheus-client==0.2.0
 pyasn1==0.4.8
 pycparser==2.20
 PyPDF2==1.26.0

tests/app/test_route_authentication.py

@@ -6,7 +6,11 @@ def test_all_routes_have_authentication(client):
     blueprint_names = set(client.application.blueprints.keys())
     assert blueprint_names == before_req_funcs
 
+    routes_blueprint_names = set([x.split('.')[0] for x in client.application.view_functions.keys()])
+
     # The static route is always available by default for a Flask app to serve anything in the static folder.
-    routes_blueprint_names = set(
+    routes_blueprint_names.remove('static')
-        [x.split('.')[0] for x in client.application.view_functions.keys() if x.split('.')[0] != 'static'])
+
+    # The metrics route is not protected by auth as it's available to be scraped by Prometheus
+    routes_blueprint_names.remove('metrics')
     assert sorted(blueprint_names) == sorted(routes_blueprint_names)