Switch to your Gateway terminal window. Navigate to the [WORKSHOP]/5-dropping-spans directory and open the gateway.yaml and add the following configuration to the processors section:

Add a filter processor: Configure the OpenTelemetry Collector to drop spans with the name "/_healthz":

  
  filter/health:                  # Defines a filter processor
    error_mode: ignore            # Ignore errors
    traces:                       # Filtering rules for traces
      span:                       # Exclude spans named "/_healthz"  
        - 'name == "/_healthz"'

Add the filter processor: Make sure you add the filter to the traces pipeline. Filtering should be applied as early as possible, ideally right after the memory_limiter and before the batch processor:

    traces:
      receivers:                
        - otlp                    # OTLP Receiver
      processors:                
        - memory_limiter          # Manage memory usage
        - filter/health           # Filter Processor. Filter's out Data based on rules
        - resource/add_mode       # Add metadata about collector mode
        - batch                   # Groups Data before send
      exporters:               
        - debug                   # Debug Exporter
        - file/traces             # File Exporter for Trace

Create “noisy” ‘healthz’ span:

1. Create a new file called health.json in the 5-dropping-spans directory.
2. Copy and paste the following JSON into the health.json file.
3. Note the span name is set to {"name":"healthz"} in the json.

{"resourceSpans":[{"resource":{"attributes":[{"key":"service.name","value":{"stringValue":"frontend"}}]},"scopeSpans":[{"scope":{"name":"healthz","version":"1.0.0","attributes":[{"key":"my.scope.attribute","value":{"stringValue":"some scope attribute"}}]},"spans":[{"traceId":"5B8EFFF798038103D269B633813FC60C","spanId":"EEE19B7EC3C1B174","parentSpanId":"EEE19B7EC3C1B173","name":"/_healthz","startTimeUnixNano":"1544712660000000000","endTimeUnixNano":"1544712661000000000","kind":2,"attributes":[]}]}]}]}

WORKSHOP
├── 1-agent
├── 2-gateway
├── 3-filelog
├── 4-resilience
├── 5-dropping-spans
│   ├───checkpoint-dir
│   ├── agent.yaml
│   ├── gateway.yaml
│   ├── health.json
│   ├── log-gen.sh (or .ps1)
│   └── trace.json
└── otelcol

Start the Gateway: In the Gateway terminal window navigate to the [WORKSHOP]/5-dropping-spans directory and run:

../otelcol --config=gateway.yaml

Start the Agent: In the Agent terminal window navigate to the [WORKSHOP]/5-dropping-spans directory and run:

../otelcol --config=agent.yaml

Send the new health.json payload: In the Test terminal window navigate to the [WORKSHOP]/5-dropping-spans directory and run the curl command below. (Windows use curl.exe).

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

Verify Agent Debug output shows the healthz span: Confirm that the span span payload is sent, Check the agent’s debug output to see the span data like the snippet below:

<snip>
Span #0
    Trace ID       : 5b8efff798038103d269b633813fc60c
    Parent ID      : eee19b7ec3c1b173
    ID             : eee19b7ec3c1b174
    Name           : /_healthz
    Kind           : Server
<snip>

The Agent has forward the span to the Gateway.

Check the Gateway Debug output:

1. The Gateway should NOT show any span data received. This is because the Gateway is configured with a filter to drop spans named "/_healthz", so the span will be discarded/dropped and not processed further.
2. Confirm normal span are processed by using the cURL command with the trace.json file again. This time, you should see both the agent and gateway process the spans successfully.