1.2 Test Agent Configuration

Once you’ve updated the configuration, you’re ready to proceed to running the OpenTelemetry Collector with your new setup. This exercise sets the foundation for understanding how data flows through the OpenTelemetry Collector.

Exercise

Find your Agent terminal window:

Change into the [WORKSHOP]/1-agent folder
Run the following command:

../otelcol --config=agent.yaml

In this workshop, we use macOS/Linux commands by default. If you’re using Windows, adjust the commands as needed i.e. use ./otelcol.exe.

Note

On Windows, a dialog box may appear asking if you want to grant public and private network access to otelcol.exe. Click “Allow” to proceed.

Exercise

Verify debug output: If everything is set up correctly, the first and last lines of the output should display:

2025/01/13T12:43:51 settings.go:478: Set config to [agent.yaml]
<snip to the end>
2025-01-13T12:43:51.747+0100 info service@v0.117.0/service.go:261 Everything is ready. Begin running and processing data.

Create a test span file: Instead of instrumenting an application, we will simulate sending trace data to the OpenTelemetry Collector using cURL. The trace data, formatted in JSON, represents what an instrumentation library would typically generate and send.

Find your Tests Terminal window and change into the [WORKSHOP]/1-agent directory.
Copy and paste the following span data into a new file named trace.json:

This file will allow us to test how the OpenTelemetry Collector processes and send spans that are part of a trace, without requiring actual application instrumentation.

{"resourceSpans":[{"resource":{"attributes":[{"key":"service.name","value":{"stringValue":"my.service"}},{"key":"deployment.environment","value":{"stringValue":"my.environment"}}]},"scopeSpans":[{"scope":{"name":"my.library","version":"1.0.0","attributes":[{"key":"my.scope.attribute","value":{"stringValue":"some scope attribute"}}]},"spans":[{"traceId":"5B8EFFF798038103D269B633813FC60C","spanId":"EEE19B7EC3C1B174","parentSpanId":"EEE19B7EC3C1B173","name":"I'm a server span","startTimeUnixNano":"1544712660000000000","endTimeUnixNano":"1544712661000000000","kind":2,"attributes":[{"key":"user.name","value":{"stringValue":"George Lucas"}},{"key":"user.phone_number","value":{"stringValue":"+1555-867-5309"}},{"key":"user.email","value":{"stringValue":"george@deathstar.email"}},{"key":"user.account_password","value":{"stringValue":"LOTR>StarWars1-2-3"}},{"key":"user.visa","value":{"stringValue":"4111 1111 1111 1111"}},{"key":"user.amex","value":{"stringValue":"3782 822463 10005"}},{"key":"user.mastercard","value":{"stringValue":"5555 5555 5555 4444"}}]}]}]}]}

[WORKSHOP]
├── 1-agent         # Module directory
│   └── agent.yaml  # OpenTelemetry Collector configuration file
│   └── trace.json  # Sample trace data
└── otelcol         # OpenTelemetry Collector binary

Send a test span: Run the following command to send a span to the agent:

 curl -X POST -i http://localhost:4318/v1/traces -H "Content-Type: application/json" -d "@trace.json"

HTTP/1.1 200 OK
Content-Type: application/json
Date: Mon, 27 Jan 2025 09:51:02 GMT
Content-Length: 21

{"partialSuccess":{}}%

Info

HTTP/1.1 200 OK: Confirms the request was processed successfully.
{"partialSuccess":{}}: Indicates 100% success, as the field is empty. In case of a partial failure, this field will include details about any failed parts.

Note

On Windows, you may encounter the following error:

Invoke-WebRequest : Cannot bind parameter ‘Headers’. Cannot convert the “Content-Type: application/json” …

To resolve this, use curl.exe instead of just curl.

Exercise

Verify Debug Output:

Find the Agent terminal window and check the collector’s debug output. You should see the Debug entries related to the span you just sent.
We are showing the first and last lines of the debug log for that span. To get the full context, Use the Complete Debug Output Button to review.

2025-02-03T12:46:25.675+0100    info ResourceSpans #0
<snip>
        {"kind": "exporter", "data_type": "traces", "name": "debug"}

Complete Debug Output

2025-02-03T12:46:25.675+0100    info ResourceSpans #0  
Resource SchemaURL:
Resource attributes:
     -> service.name: Str(my.service)
     -> deployment.environment: Str(my.environment)
ScopeSpans #0
ScopeSpans SchemaURL:
InstrumentationScope my.library 1.0.0
InstrumentationScope attributes:
     -> my.scope.attribute: Str(some scope attribute)
Span #0
    Trace ID       : 5b8efff798038103d269b633813fc60c
    Parent ID      : eee19b7ec3c1b173
    ID             : eee19b7ec3c1b174
    Name           : I'm a server span
    Kind           : Server
    Start time     : 2018-12-13 14:51:00 +0000 UTC
    End time       : 2018-12-13 14:51:01 +0000 UTC
    Status code    : Unset
    Status message :
Attributes:
     -> user.name: Str(George Lucas)
     -> user.phone_number: Str(+1555-867-5309)
     -> user.email: Str(george@deathstar.email)
     -> user.account_password: Str(LOTR>StarWars1-2-3)
     -> user.visa: Str(4111 1111 1111 1111)
     -> user.amex: Str(3782 822463 10005)
     -> user.mastercard: Str(5555 5555 5555 4444)
        {"kind": "exporter", "data_type": "traces", "name": "debug"}