OpenCensus

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Run it locally
How does it work?
Configure Exporter
Configure Sampler
Using the Tracer
Create a span
Create a child span
References

Run it locally

Clone the example repository: git clone https://github.com/opencensus-otherwork/opencensus-quickstarts
Change to the example directory: cd opencensus-quickstarts/python/tracing-to-zipkin
Install dependencies: pip install opencensus opencensus-ext-zipkin
Download Zipkin: curl -sSL https://zipkin.io/quickstart.sh | bash -s
Start Zipkin: java -jar zipkin.jar
Run the code: python tracingtozipkin.py
Navigate to Zipkin Web UI: http://localhost:9411
Click Find Traces, and you should see a trace.
Click into that, and you should see the details.

# 1a. Setup the exporter
ze = ZipkinExporter(service_name="python-quickstart",
                                host_name='localhost',
                                port=9411,
                                endpoint='/api/v2/spans')
# 1b. Set the tracer to use the exporter
# 2. Configure 100% sample rate, otherwise, few traces will be sampled.
# 3. Get the global singleton Tracer object
tracer = Tracer(exporter=ze, sampler=AlwaysOnSampler())

def main():
    # 4. Create a scoped span. The span will close at the end of the block.
    with tracer.span(name="main") as span:
        for i in range(0, 10):
            doWork()

#!/usr/bin/env python

import os
from datetime import datetime
import time
import sys

from opencensus.trace.tracer import Tracer
from opencensus.trace import time_event as time_event_module
from opencensus.ext.zipkin.trace_exporter import ZipkinExporter
from opencensus.trace.samplers import AlwaysOnSampler

# 1a. Setup the exporter
ze = ZipkinExporter(service_name="python-quickstart",
                                host_name='localhost',
                                port=9411,
                                endpoint='/api/v2/spans')
# 1b. Set the tracer to use the exporter
# 2. Configure 100% sample rate, otherwise, few traces will be sampled.
# 3. Get the global singleton Tracer object
tracer = Tracer(exporter=ze, sampler=always_on.AlwaysOnSampler())

def main():
    # 4. Create a scoped span. The span will close at the end of the block.
    with tracer.span(name="main") as span:
        for i in range(0, 10):
            doWork()

def doWork():
    # 5. Start another span. Because this is within the scope of the "main" span,
    # this will automatically be a child span.
    with tracer.span(name="doWork") as span:
        print("doing busy work")
        try:
            time.sleep(0.1)
        except:
            # 6. Set status upon error
            span.status = Status(5, "Error occurred")

        # 7. Annotate our span to capture metadata about our operation
        span.add_annotation("invoking doWork")

if __name__ == "__main__":
    main()

Configure Exporter

OpenCensus can export traces to different distributed tracing stores (such as Zipkin, Jeager, Stackdriver Trace). In (1), we configure OpenCensus to export to Zipkin, which is listening on localhost port 9411, and all of the traces from this program will be associated with a service name python-quickstart.

# 1a. Setup the exporter
ze = ZipkinExporter(service_name="python-quickstart",
                                host_name='localhost',
                                port=9411,
                                endpoint='/api/v2/spans')
# 1b. Set the tracer to use the exporter
tracer = Tracer(exporter=ze, sampler=always_on.AlwaysOnSampler())

Configure Sampler

Configure 100% sample rate, otherwise, few traces will be sampled.

# 2. Configure 100% sample rate, otherwise, few traces will be sampled.
tracer = Tracer(exporter=ze, sampler=always_on.AlwaysOnSampler())

Using the Tracer

To start a trace, you first need to get a reference to the Tracer (3). It can be retrieved as a global singleton.

# 3. Get the global singleton Tracer object
tracer = Tracer(exporter=ze, sampler=always_on.AlwaysOnSampler())

Create a span

To create a span in a trace, we used the Tracer to start a new span (4). A span will automatically close at the end of the block.

# 4. Create a scoped span. The span will close at the end of the block.
with tracer.span(name="main") as span:

Create a child span

The main method calls doWork a number of times. Each invocation also generates a child span. Take a look at the doWork method.

def doWork():
    # 5. Start another span. Because this is within the scope of the "main" span,
    # this will automatically be a child span.
    with tracer.span(name="doWork") as span:
        print("doing busy work")
        try:
            time.sleep(0.1)
        except:
            # 6. Set status upon error
            span.status = Status(5, "Error occurred")

        # 7. Annotate our span to capture metadata about our operation
        span.add_annotation("invoking doWork")

Set the Status of the span

We can set the status of our span to create more observability of our traced operations.

# 6. Set status upon error
span.status = Status(5, "Error occurred")

Create an Annotation

An annotation tells a descriptive story in text of an event that occurred during a span’s lifetime.

# 7. Annotate our span to capture metadata about our operation
span.add_annotation("invoking doWork")

References

Resource	URL
Zipkin project	https://zipkin.io/
Setting up Zipkin	Zipkin Codelab
Python exporters	Python exporters

Tracing