DDTrace Python

Install Dependencies¶

Install the DDTrace SDK:

pip install ddtrace

Running the Application¶

Host ApplicationKubernetes

Note: Here, ddtrace-run is used to start the Python application.

DD_SERVICE="<YOUR-SERVICE-Name>" \
  DD_ENV="<YOUR-ENV-NAME>" \
  DD_LOGS_INJECTION=true \
  ddtrace-run python my_app.py

apiVersion: apps/v1
kind: Deployment
spec:
  template:
    spec:
      containers:
        - name: <CONTAINER_NAME>
          image: <CONTAINER_IMAGE>/<TAG>
          env:
            - name: DD_AGENT_HOST
              value: "datakit-service.datakit.svc"
            - name: DD_TRACE_AGENT_PORT
              value: "9529"
            - name: DD_ENV
              value: <YOUR-ENV-NAME>
            - name: DD_SERVICE
              value: <YOUR-SERVICE-NAME>
            - name: DD_LOGS_INJECTION
              value: "true"

In addition, the following other common options can be enabled.

Profiling¶

DD_PROFILING_ENABLED=true \
  ddtrace-run python my_app.py

Sampling Rate¶

Set a sampling rate of 0.8, so only 80% of the traces will be retained.

DD_TRACE_SAMPLE_RATE="0.8" \
  ddtrace-run python my_app.py

Enable Python Runtime Metrics Collection¶

The statsd collector needs to be enabled here.

DD_RUNTIME_METRICS_ENABLED=true \
  ddtrace-run python my_app.py

Code Example¶

service_a.py

from flask import Flask, request
import requests, os
from ddtrace import tracer

app = Flask(__name__)

def shutdown_server():
    func = request.environ.get('werkzeug.server.shutdown')
    if func is None:
        raise RuntimeError('Not running with the Werkzeug Server')
    func()

@app.route('/a',  methods=['GET'])
def index():
    requests.get('http://127.0.0.1:54322/b') 
    return 'OK', 200

@app.route('/stop',  methods=['GET'])
def stop():
    shutdown_server()
    return 'Server shutting down...\n'

# Start service A: HTTP service starts on port 54321
if __name__ == '__main__':
    app.run(host="0.0.0.0", port=54321, debug=True)

service_b.py

from flask import Flask, request
import os, time, requests
from ddtrace import tracer

app = Flask(__name__)

def shutdown_server():
    func = request.environ.get('werkzeug.server.shutdown')
    if func is None:
        raise RuntimeError('Not running with the Werkzeug Server')
    func()

@app.route('/b',  methods=['GET'])
def index():
    time.sleep(1)
    return 'OK', 200

@app.route('/stop',  methods=['GET'])
def stop():
    shutdown_server()
    return 'Server shutting down...\n'

# Start service B: HTTP service starts on port 54322
if __name__ == '__main__':
    app.run(host="0.0.0.0", port=54322, debug=True)

Run¶

Here, we take the commonly used Python Web Server Flask application as an example. In the example, SERVICE_A provides an HTTP service and calls the SERVICE_B HTTP service.

Run SERVICE_A

DD_SERVICE=SERVICE_A \
DD_SERVICE_MAPPING=postgres:postgresql,defaultdb:postgresql \
DD_TAGS=project:your_project_name,env:test,version:v1 \
DD_AGENT_HOST=localhost \
DD_AGENT_PORT=9529 \
ddtrace-run python3 service_a.py &> a.log &

Run SERVICE_B

DD_SERVICE=SERVICE_B \
DD_SERVICE_MAPPING=postgres:postgresql,defaultdb:postgresql \
DD_TAGS=project:your_project_name,env:test,version:v1 \
DD_AGENT_HOST=localhost \
DD_AGENT_PORT=9529 \
ddtrace-run python3 service_b.py &> b.log &

Call service A to prompt it to call service B, which will generate corresponding trace data (this can be executed multiple times to trigger)

curl http://localhost:54321/a

Stop both services respectively

curl http://localhost:54321/stop
curl http://localhost:54322/stop

Environment Variable Support¶

The common environment variables supported are as follows. For a complete list of Python environment variables, refer to the DataDog Official Documentation.

DD_ENV: Sets the environment variable for the service.
DD_VERSION: The version number of the APP.
DD_SERVICE: Used to set the application's service name. When integrating with web frameworks such as Pylons, Flask, or Django, this value is passed. For Tracing without web integration, it is recommended to set the service name in the code.
DD_SERVICE_MAPPING: Defines service name mappings for renaming services in Tracing.
DD_TAGS: Adds default Tags to each Span in the format key:val,key:val.
DD_AGENT_HOST: The hostname where Datakit is listening, default is localhost.
DD_AGENT_PORT: The port number where Datakit is listening, default is 9529.
DD_TRACE_SAMPLE_RATE: Sets the sampling rate from 0.0 (0%) to 1.0 (100%).