Add new file exporters: The routing connector requires different targets for routing. In the Gateway terminal create two new file exporters, file/traces/route1-regular and file/traces/route2-security, to ensure data is directed correctly in the exporters section of the gateway.yaml:

  file/traces/route1-regular:                     # Exporter for regular traces
    path: "./gateway-traces-route1-regular.out"   # Path for saving trace data
    append: false                                 # Overwrite the file each time
  file/traces/route2-security:                    # Exporter for security traces
    path: "./gateway-traces-route2-security.out"  # Path for saving trace data
    append: false                                 # Overwrite the file each time 

Enable Routing by adding the routing connector. In OpenTelemetry configuration files, connectors have their own dedicated section, similar to receivers and processors.

Find and uncomment the #connectors: section. Then, add the following below the connectors: section:

  routing:
    default_pipelines: [traces/route1-regular]  # Default pipeline if no rule matches
    error_mode: ignore                          # Ignore errors in routing
    table:                                      # Define routing rules
      # Routes spans to a target pipeline if the resourceSpan attribute matches the rule
      - statement: route() where attributes["deployment.environment"] == "security-applications"
        pipelines: [traces/route2-security]     # Security target pipeline 

Update the original traces pipeline to use routing:

1. To enable routing, update the original traces pipeline to use routing as the only exporter. This ensures all span data is sent through the Routing Connector for evaluation and then onwards to connected pipelines. Also, remove all processors and replace it with an empty array ([]) as this will now behandeld in the traces/route1-regular and traces/route2-security pipelines, allowing for custom behaviour for each route. Your traces: configuration should look like this:

   traces:                       # Traces pipeline
     receivers:
     - otlp                      # OTLP receiver
     processors: []              # Processors for traces
     exporters:
     - routing

Add both the route1-regular and route2-security traces pipelines below the existing traces pipeline:

1. Configure Route1-regular pipeline: This pipeline will handle all spans that have no match in the routing table in the connector. Notice this uses routing as its only receiver and will recieve data thought its connection from the original traces pipeline.

       traces/route1-regular:         # Default pipeline for unmatched spans
         receivers: 
         - routing                    # Receive data from the routing connector
         processors:
         - memory_limiter             # Memory Limiter Processor
         - resource/add_mode          # Adds collector mode metadata
         - batch
         exporters:
         - debug                      # Debug Exporter 
         - file/traces/route1-regular # File Exporter for unmatched spans 

2. Add the route2-security pipeline: This pipeline processes all spans that do match our rule "[deployment.environment"] == "security-applications" in the the routing rule. This pipeline is also using routing as its receiver. Add this pipline below the traces/route1-regular one.

       traces/route2-security:         # Default pipeline for unmatched spans
         receivers: 
         - routing                     # Receive data from the routing connector
         processors:
         - memory_limiter              # Memory Limiter Processor
         - resource/add_mode           # Adds collector mode metadata
         - batch
         exporters:
         - debug                       # Debug exporter
         - file/traces/route2-security # File exporter for unmatched spans

In this section, we will test the routing rule configured for the Gateway. The expected result is that a span generated by the loadgen that match the "[deployment.environment"] == "security-applications" rule will be sent to the gateway-traces-route2-security.out file.

Start the Gateway: In your Gateway terminal window start the Gateway.

../otelcol --config gateway.yaml

Start the Agent: In your Agent terminal window start the Agent.

../otelcol --config agent.yaml

Send a Regular Span: In the Loadgen terminal window send a regular span using the loadgen:

../loadgen -count 1

Both the Agent and Gateway will display debug information. The gateway will also generate a new gateway-traces-route1-regular.out file, as this is now the designated destination for regular spans.

Send a Security Span: In the Loadgen terminal window send a security span using the security flag:

../loadgen -security -count 1

Again, both the Agent and Gateway should display debug information, including the span you just sent. This time, the Gateway will write a line to the gateway-traces-route2-security.out file, which is designated for spans where the deployment.environment resource attribute matches "security-applications".

jq -c '.resourceSpans[] as $resource | $resource.scopeSpans[].spans[] | {spanId: .spanId, deploymentEnvironment: ($resource.resource.attributes[] | select(.key == "deployment.environment") | .value.stringValue)}' gateway-traces-route2-security.out

{"spanId":"cb799e92e26d5782","deploymentEnvironment":"security-applications"}

You can repeat this scenario multiple times, and each trace will be written to its corresponding output file.