blueswen / flask-monitoring

Monitor Flask application through custom StatsD metrics with Prometheus and Grafana.

Flask Monitoring

Monitor Flask application through custom StatsD metrics with Prometheus and Grafana.

1. Flask app sends StatsD format metrics by UDP to statsd_exporter
2. Prometheus scrapes prometheus format metrics from statsd_exporter
3. Grafana queries data from Prometheus

+-----------------+                     +-------------------+                        +--------------+               +-----------+
|  Flask(StatsD)  |---(UDP repeater)--->|  statsd_exporter  |<---(scrape /metrics)---|  Prometheus  | <---(query)---|  Grafana  |
+-----------------+                     +-------------------+                        +--------------+               +-----------+

Quick Start

1. Build application image and start all service with docker-compose

   docker-compose build
   docker-compose up -d

2. Send requests with siege to flask app

   bash request-script.sh

3. Check predefined dashboard flask monitoring on Grafana http://localhost:3000/

   Dashboard screenshot:

   

   Dashboard is also available on Grafana Dashboards.

Details

Flask

1. Use Datadog Python library to send StatsD format metrics in flask_app/utils.py.
   1. setting_statsd: Register StatsD host and port with environment variable STATSD_HOST, STATSD_PORT
   2. StatsdMiddleware: Add custom metrics
2. Initial statsd with setting_statsd, and add StatsdMiddleware to flask app in flask_app/app.py.

Statsd Exporter

statsd exporter receives StatsD-style metrics and exports them as Prometheus metrics.

Ports:

1. 9125: default StatsD request listen port, send StatsD request to this port
2. 9102: Web expose port, get prometheus metrics from this port

Prometheus metrics is available on http://localhost:9102/metrics.

Prometheus

Setting scrape job of statsd-exporter with config file etc/prometheus/prometheus.yml.

scrape_configs:
  - job_name: 'statsd-exporter'
    static_configs:
      - targets: ['statsd-exporter:9102']

Prometheus build-in web UI is available on http://localhost:9090.

Grafana

Add prometheus to data source with config file etc/grafana/datasource.yml.

datasources:
  # <string, required> name of the datasource. Required
  - name: Prometheus
    # <string, required> datasource type. Required
    type: prometheus
    # <string, required> access mode. proxy or direct (Server or Browser in the UI). Required
    access: proxy
    # <int> org id. will default to orgId 1 if not specified
    orgId: 1
    # <string> custom UID which can be used to reference this datasource in other parts of the configuration, if not specified will be generated automatically
    # uid: my_unique_uid
    # <string> url
    url: http://prometheus:9090
    # <bool> mark as default datasource. Max one per org
    isDefault: true
    version: 1
    # <bool> allow users to edit datasources from the UI.
    editable: false

Load predefined dashboard with etc/dashboards.yaml and etc/dashboards/flask-monitoring.json.

# grafana in docker-compose.yaml
grafana:
    image: grafana/grafana:8.4.3
    volumes:
      - ./etc/grafana/:/etc/grafana/provisioning/datasources
      - ./etc/dashboards.yaml:/etc/grafana/provisioning/dashboards/dashboards.yaml # dashboard setting
      - ./etc/dashboards:/etc/grafana/dashboards # dashboard json files directory

Dashboard

Flask monitoring dashboard from etc/dashboards/flask-monitoring.json

This dashboard follows RED method proposed by Weaveworks, and monitors three key metrics:

1. Rate: requests rate, request count over past 24 hours
2. Errors: 2xx rate, 5xx rate, cumulative number of each status code over past 24 hours
3. Duration: average request duration, request duration distribution (PR50, PR90, PR99)

Reference

1. Monitoring Gunicorn with Prometheus
2. Gunicorn Dashboard Sample
3. Gunircorn worker type in different scenario [Chinese]
4. Grafana datasource provisioning
5. The RED Method: key metrics for microservices architecture