title: Three Step Demo

weight: 1

This tutorial shows the quickest way to get started with the Prometheus Python library.

**One**: Install the client:

**Two**: Paste the following into a Python interpreter:

from prometheus_client import start_http_server, Summary

import random

import time

REQUEST_TIME = Summary('request_processing_seconds', 'Time spent processing request')

@REQUEST_TIME.time()

def process_request(t):

"""A dummy function that takes some time."""

time.sleep(t)

if __name__ == '__main__':

# Start up the server to expose the metrics.

start_http_server(8000)

# Generate some requests.

while True:

process_request(random.random())

**Three**: Visit [http://localhost:8000/](http://localhost:8000/) to view the metrics.

From one easy to use decorator you get:

* `request_processing_seconds_count`: Number of times this function was called.

* `request_processing_seconds_sum`: Total amount of time spent in this function.

Prometheus's `rate` function allows calculation of both requests per second,

and latency over time from this data.

In addition if you're on Linux the `process` metrics expose CPU, memory and

other information about the process for free!