python-flask-app

Instrumented Python Flask application

In this sandbox, a Prometheus instance scrapes metrics from a simple Python Flask web application.

Usage

To start the sandbox:

# In the foreground
make run # docker-compose up --build

# In detached mode
make run-detached # docker-compose up --build --detach

This will start up two services:

Service	Description
prometheus	A Prometheus instance that's configured to scrape metrics from the Go application running on port 2112
myapp	A simple Python Flask web application exports a LATENCY_HISTOGRAM and a REQUEST_COUNTER

Create some example web traffic to the app:

for n in {1..100}; do
    curl http://localhost:5000/test-endpoint
done

Once the sandbox is up and running, navigate to http://localhost:9090/graph in your browser and enter myapp_request_count_total into the expression bar to see the most up-to-date value of the counter.

You can also see this metrics by "scraping" the Flask web server's /metrics endpoint:

curl localhost:5000/metrics | grep myapp_request_count_total
# HELP myapp_request_count_total myapp HTTP request count
# TYPE myapp_request_count_total counter
myapp_request_count_total{endpoint="/metrics",method="GET",status="200"} 17.0

Here are some example metrics to explore in the Prometheus expression browser:

• myapp_request_count_total{endpoint="/test-endpoint"}
• myapp_request_latency_seconds_bucket{endpoint="/test-endpoint",le="0.1"}