# Tail sampling with OpenTelemetry using Docker compose Copy as Markdown[Open in ChatGPT](https://chatgpt.com/?q=Read%20https%3A%2F%2Fdocs-docusaurus.kinsta.page%2Fopentelemetry%2Ftail-sampling%2Ftail-sampling-with-opentelemetry-using-docker-compose.md%20and%20help%20me%20with%20my%20question%20about%20this%20Coralogix%20documentation%20page.)[Open in Claude](https://claude.ai/new?q=Read%20https%3A%2F%2Fdocs-docusaurus.kinsta.page%2Fopentelemetry%2Ftail-sampling%2Ftail-sampling-with-opentelemetry-using-docker-compose.md%20and%20help%20me%20with%20my%20question%20about%20this%20Coralogix%20documentation%20page.) The following tutorial demonstrates how to configure a Docker Compose environment, deploy OpenTelemetry to collect traces, and enable trace sampling. We will cover an example of enabling tail samples using the small trace generating application. ## Prerequisites[​](#prerequisites "Direct link to Prerequisites") * Docker installed * Docker Compose installed * Coralogix [Send-Your-Data API key](https://docs-docusaurus.kinsta.page/user-guides/account-management/api-keys/send-your-data-api-key/.md) ## How it Works[​](#how-it-works "Direct link to How it Works") [![](/assets/images/docker-flow-daig-7f76968413b868fed4c5569833e82d37.webp)](https://docs-docusaurus.kinsta.page/assets/images/docker-flow-daig-7f76968413b868fed4c5569833e82d37.webp) 1. Traces from the application are sent to an OpenTelemetry Collector. 2. The Collector, acting as a load balancer, forwards traces to one or more OpenTelemetry gateways. This ensures that traces with the same ID always go to the same gateway, irrespective of span or order. 3. The gateway uses the TraceID to group traces and applies tail sampling. It then forwards the traces to the Coralogix backend. ## Setup Demo Application[​](#setup-demo-application "Direct link to Setup Demo Application") ### 1. Create an `.env` file[​](#1-create-an-env-file "Direct link to 1-create-an-env-file") Create a file named `.env` and include the following content: ``` CORALOGIX_DOMAIN= CORALOGIX_APP_NAME=otel CORALOGIX_SUBSYS_NAME=otel-demo CORALOGIX_PRIVATE_KEY= OTEL_IMAGE=otel/opentelemetry-collector-contrib:0.94.0 ``` These values will configure the Coralogix backend and the OpenTelemetry Collector and Gateway. ### 2. Create OpenTelemetry Collector Configuration[​](#2-create-opentelemetry-collector-configuration "Direct link to 2. Create OpenTelemetry Collector Configuration") Create a file named `otel-collector-config.yaml` with the following content: ``` receivers: otlp: protocols: grpc: exporters: loadbalancing: protocol: otlp: tls: insecure: true timeout: 1s resolver: static: hostnames: - otel-col-gateway-1:4317 - otel-col-gateway-2:4317 processors: batch/traces: send_batch_size: 1024 send_batch_max_size: 2048 timeout: "1s" resourcedetection: detectors: [system, env] timeout: 5s override: true connectors: spanmetrics: service: pipelines: traces: receivers: [ otlp ] processors: [ batch/traces ] exporters: [ loadbalancing ] ``` This configuration sets up the OpenTelemetry Collector to receive traces and forward them to the OpenTelemetry Gateway, using a load balancing exporter. ### 3. Create OpenTelemetry Gateway Configuration[​](#3-create-opentelemetry-gateway-configuration "Direct link to 3. Create OpenTelemetry Gateway Configuration") Create a file named `otel-gateway-config.yaml` with the following content: ``` extensions: health_check: receivers: otlp: protocols: grpc: endpoint: 0.0.0.0:4317 processors: batch/traces: send_batch_size: 1024 send_batch_max_size: 2048 timeout: "1s" resourcedetection: detectors: [system, env] timeout: 5s override: true tail_sampling: decision_wait: 10s num_traces: 100 expected_new_traces_per_sec: 10 policies: [ { name: errors-policy, type: status_code, status_code: {status_codes: [ERROR]} }, { name: randomized-policy, type: probabilistic, probabilistic: {sampling_percentage: 25} }, ] attributes/shipper: actions: - key: shipper action: insert value: '${SHIPPER_NAME}' exporters: logging: coralogix: domain: "${CORALOGIX_DOMAIN}" private_key: "${CORALOGIX_PRIVATE_KEY}" application_name: "${CORALOGIX_APP_NAME}" subsystem_name: "${CORALOGIX_SUBSYS_NAME}" timeout: 30s service: extensions: [health_check] pipelines: traces: receivers: [otlp] processors: [attributes/shipper, tail_sampling, batch/traces, resourcedetection] exporters: [coralogix, logging] ``` This configuration sets up the OpenTelemetry Gateway to receive traces from the OpenTelemetry Collector, apply tail sampling, and forward the traces to the Coralogix backend. ### 4. Create a Docker Compose File[​](#4-create-a-docker-compose-file "Direct link to 4. Create a Docker Compose File") ``` version: "3" services: go-otel-traces-demo: container_name: go-otel-traces-demo image: public.ecr.aws/c1s3k2h4/go-otel-traces-demo:latest environment: - CX_ENDPOINT=otelcol:4317 otelcol: image: otel/opentelemetry-collector-contrib:0.94.0 container_name: otel-col deploy: resources: limits: memory: 100M restart: unless-stopped command: [ "--config=/etc/otelcol-config.yml" ] volumes: - ./otelcol-config.yml:/etc/otelcol-config.yml ports: - "4317" - "4318:4318" depends_on: - otelcol_gateway_1 - otelcol_gateway_2 otelcol_gateway_1: image: otel/opentelemetry-collector-contrib:0.94.0 container_name: otel-col-gateway-1 deploy: resources: limits: memory: 100M restart: unless-stopped command: [ "--config=/etc/otelcol-config.yml" ] volumes: - ./otel-gateway.yml:/etc/otelcol-config.yml ports: - "4317" - "4318" environment: - CORALOGIX_DOMAIN - CORALOGIX_APP_NAME - CORALOGIX_SUBSYS_NAME - CORALOGIX_PRIVATE_KEY - SHIPPER_NAME=gateway-1 otelcol_gateway_2: image: otel/opentelemetry-collector-contrib:0.94.0 container_name: otel-col-gateway-2 deploy: resources: limits: memory: 100M restart: unless-stopped command: [ "--config=/etc/otelcol-config.yml" ] volumes: - ./otel-gateway.yml:/etc/otelcol-config.yml ports: - "4317" - "4318" environment: - CORALOGIX_DOMAIN - CORALOGIX_APP_NAME - CORALOGIX_SUBSYS_NAME - CORALOGIX_PRIVATE_KEY - SHIPPER_NAME=gateway-2 ``` This Docker Compose file sets up the application, OpenTelemetry Collector, and OpenTelemetry Gateway. The application sends traces to the Collector, which forwards them to the Gateway. The Gateway applies tail sampling and forwards the traces to the Coralogix backend. Note: The `otelcol` service mounts `otel-collector-config.yaml`, and the `otelcol_gateway_1` and `otelcol_gateway_2` services mount `otel-gateway-config.yaml`. These files must be in the same directory as the Docker Compose file. Also, `CORALOGIX_DOMAIN`, `CORALOGIX_APP_NAME`, `CORALOGIX_SUBSYS_NAME`, and `CORALOGIX_PRIVATE_KEY` environment variables configure the Coralogix backend. ### 5. Start the Docker Compose Environment[​](#5-start-the-docker-compose-environment "Direct link to 5. Start the Docker Compose Environment") Run the following command to start the Docker Compose environment: ``` docker-compose up -d ``` ## Validation[​](#validation "Direct link to Validation") Check your Coralogix dashboard for telemetry data. Traces should appear from the configured gateways. [![](/assets/images/traces-console-1024x608-80fdde34ff08ff35db205130c591d1d9.jpg)](https://docs-docusaurus.kinsta.page/assets/images/traces-console-1024x608-80fdde34ff08ff35db205130c591d1d9.jpg)