Testing OpenTelemetry configuration pipelines without resorting to instrumented applications, particularly for traces, can be a bit of a pain. Typically, you just want to validate you can get an exported/generated signal through your pipeline, which may not be the OpenTelemetry Collector (e.g., FluentBit or commercial solutions such as DataDog). This led to the creation of Tracegen, and then the larger Telementrygen.

You can use Tracegen or Telemetrygen by either downloading and running the Go app from GitHub or using the Docker file. But there are a couple of challenges:

• On initial investigation, these utilities appear wrapped up in the larger opentelemetry-collector-contrib. While potentially useful, shaking out your OTel pipelining is somewhat overkill.
• We can install the app locally with the following command, but then we need to set up Golang in the environment.

go install github.com/open-telemetry/opentelemetry-collector-contrib/cmd/telemetrygen@latest

• Fortunately, there is a Docker image that just contains the tool, but to use it, we need to know what the parameters are to override the container defaults. The only irritant is that you either need to mess about with the container to get at the information (i.e., run the — help options) or install the utility (the parameters are not in the GitHub docs), so we’ve teased out all the options into the following table.

The following table’s Signal column All means it can be applied to Metrics, Traces, or Logs. Otherwise we’ve named the signal type that the parameter can be used with.

Signal	Parameter/Flag	Description
Trace	–batch	Whether to batch traces (default true)
All	–ca-cert string	Trusted Certificate Authority to verify server certificate
Traces	–child-spans int	Client certificate file
All	–client-key string	Client private key file
All	–duration duration	For how long to run the test
All	-h, –help {traces|metrics|logs}	help – with give you the basic help if no parameter is passed. Or the signal type help when used with the signal name e.g. telemetrygen traces --help
All	–interval duration	Reporting interval (default 1s)
Traces	–marshal	Whether to marshal trace context via HTTP headers
All	–mtls	Whether to require client authentication for mTLS
All	–otlp-attributes map[string]string	Custom resource attributes to use. The value is expected in the format key=”value”. Note you may need to escape the quotes when using the tool from a cli. Flag may be repeated to set multiple attributes (e.g --otlp-attributes key1=\"value1\" --otlp-attributes key2=\"value2\")
All	–otlp-endpoint string	Destination endpoint for exporting logs, metrics and traces
All	–otlp-header map[string]string	Custom header to be passed along with each OTLP request. The value is expected in the format key=”value”. Note you may need to escape the quotes when using the tool from a cli. Flag may be repeated to set multiple headers (e.g --otlp-header key1=\"value1\" --otlp-header key2=\"value2\")
All	–otlp-http	Whether to use HTTP exporter rather than a gRPC one
All	–otlp-http-url-path string	Which URL path to write to (default "/v1/traces")
All	–otlp-insecure	Whether to enable client transport security for the exporter’s grpc or http connection
All	–rate int	Approximately how many metrics per second each worker should generate. Zero means no throttling.
Traces	–service string	Service name to use (default "telemetrygen")
Traces	–size int	Desired minimum size in MB of string data for each trace generated. This can be used to test traces with large payloads, i.e. when testing the OTLP receiver endpoint max receive size.
Traces	–span-duration duration	The duration of each generated span. (default 123µs)
Traces	–status-code string	Status code to use for the spans, one of (Unset, Error, Ok) or the equivalent integer (0,1,2) (default “0”)
All	–telemetry-attributes map[string]string	Number of traces to generate in each worker (ignored if the duration is provided) (default 1)
Traces	–traces int	Number of traces to generate in each worker (ignored if duration is provided) (default 1)
All	–workers int	Number of workers (goroutines) to run (default of 1)
Metrics	–metric-type metricType	Number of metrics to generate in each worker (ignored if the duration is provided) (default 1)
Metrics	–metrics int	Number of logs to generate in each worker (ignored if the duration is provided) (default 1)
Logs	–body string	Body of the log (default “the message”)
Logs	–logs int	The severity number of the log ranges from 1 to 24 (inclusive) (default 9)
Logs	–severity-number int32	The severity number of the log ranges from 1 to 24 (inclusive) (default 9)
Logs	–severity-text string	Severity text of the log (default “Info”)

It is worth noting that while Tracegen has similar configuration parameters, they aren’t exactly the same in the CLI, often one dash rather than two in the name for example.

The following is a simple Docker compose file that can help you use the container to conduct local testing of your collector. In this configuration, we’re sending a trace to the host machine with HTTPS disabled.

services:
  web:
    image: ghcr.io/open-telemetry/opentelemetry-collector-contrib/telemetrygen:latest
    network_mode: host
    entrypoint:
      [
        "/telemetrygen",
        "traces",
        "--otlp-insecure",
        "--otlp-endpoint",
        "host.docker.internal:4317",
      ]