OpenTelemetry Traces

Overview

OpenTelemetry Collector is a vendor-neutral service for collecting and processing OpenTelemetry data. In this article, we will introduce how to use OpenTelemetry Collector to write traces data to GreptimeDB.

Quick Start

note

Before starting the OpenTelemetry Collector, please ensure that GreptimeDB is running.

Start OpenTelemetry Collector

You can use the following command to quickly start an OpenTelemetry Collector instance, which will listen on ports 4317 (gRPC) and 4318 (HTTP):

docker run --rm \
  --network host \
  -p 4317:4317 \
  -p 4318:4318 \
  -v $(pwd)/config.yaml:/etc/otelcol-contrib/config.yaml \
  otel/opentelemetry-collector-contrib:0.123.0

The content of the config.yaml file is as follows:

receivers:
  otlp:
    protocols:
      grpc:
        endpoint: 0.0.0.0:4317
      http:
        endpoint: 0.0.0.0:4318

exporters:
  otlphttp:
    endpoint: "http://localhost:4000/v1/otlp" # The OTLP endpoint of GreptimeDB
    headers:
      x-greptime-pipeline-name: "greptime_trace_v1"
    tls:
      insecure: true

service:
  pipelines:
    traces:
      receivers: [otlp]
      exporters: [otlphttp]

Write traces data to OpenTelemetry Collector

You can configure the corresponding exporter to write traces data to the OpenTelemetry Collector. For example, you can use the environment variable OTEL_EXPORTER_OTLP_TRACES_ENDPOINT to configure the endpoint of the exporter:

export OTEL_EXPORTER_OTLP_TRACES_ENDPOINT="http://localhost:4318/v1/otlp"

For convenience, you can use the tool telemetrygen to quickly generate traces data and write it to the OpenTelemetry Collector. For more details, please refer to the OpenTelemetry Collector official documentation.

You can use the following command to install telemetrygen (please ensure you have installed Go):

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

Then you can use the following command to generate traces data and write it to the OpenTelemetry Collector:

telemetrygen traces --otlp-insecure --traces 3

The above command will generate 3 traces data and write it to the OpenTelemetry Collector via gRPC protocol.

Query traces data in GreptimeDB

GreptimeDB will write traces data to the opentelemetry_traces table in the public database by default. You can execute the following SQL statement in GreptimeDB to query traces data:

SELECT * FROM public.opentelemetry_traces \G;

Then you can get the following result(only part of the result is shown here):

*************************** 1. row ***************************
                         timestamp: 2025-04-02 09:58:43.822229
                     timestamp_end: 2025-04-02 09:58:43.822352
                     duration_nano: 123000
                    parent_span_id: NULL
                          trace_id: 1948380e459f4ca69bb4f4274b5db7ba
                           span_id: f179c8dc2171a0a0
                         span_kind: SPAN_KIND_CLIENT
                         span_name: lets-go
                  span_status_code: STATUS_CODE_UNSET
               span_status_message:
                       trace_state:
                        scope_name: telemetrygen
                     scope_version:
                      service_name: telemetrygen
span_attributes.net.sock.peer.addr: 1.2.3.4
      span_attributes.peer.service: telemetrygen-server
                       span_events: []
                        span_links: []
...

You also can use the Jaeger query interface to query traces data. Please refer to the Jaeger documentation for more details.