---
title: Connecting services with Docker Compose
linkTitle: Connecting services with Docker Compose
weight: 30 #
keywords: go, golang, prometheus, grafana, containerize, monitor
description: Learn how to connect services with Docker Compose to monitor a Golang application with Prometheus and Grafana.
---

Now that you have containerized the Golang application, you will use Docker Compose to connect your services together. You will connect the Golang application, Prometheus, and Grafana services together to monitor the Golang application with Prometheus and Grafana.

## Creating a Docker Compose file

Create a new file named `compose.yml` in the root directory of your Golang application. The Docker Compose file contains instructions to run multiple services and connect them together.

Here is a Docker Compose file for a project that uses Golang, Prometheus, and Grafana. You will also find this file in the `go-prometheus-monitoring` directory.

```yaml
services:
  api:
    container_name: go-api
    build:
      context: .
      dockerfile: Dockerfile
    image: go-api:latest
    ports:
      - 8000:8000
    networks:
      - go-network
    healthcheck:
      test: ["CMD", "curl", "-f", "http://localhost:8000/health"]
      interval: 30s
      timeout: 10s
      retries: 5
    develop:
      watch:
        - path: .
          action: rebuild
      
  prometheus:
    container_name: prometheus
    image: prom/prometheus:v2.55.0
    volumes:
      - ./Docker/prometheus.yml:/etc/prometheus/prometheus.yml
    ports:
      - 9090:9090
    networks:
      - go-network
  
  grafana:
    container_name: grafana
    image: grafana/grafana:11.3.0
    volumes:
      - ./Docker/grafana.yml:/etc/grafana/provisioning/datasources/datasource.yaml
      - grafana-data:/var/lib/grafana
    ports:
      - 3000:3000
    networks:
      - go-network
    environment:
      - GF_SECURITY_ADMIN_USER=admin
      - GF_SECURITY_ADMIN_PASSWORD=password

volumes:
  grafana-data:

networks:
  go-network:
    driver: bridge
```

## Understanding the Docker Compose file

The Docker Compose file consists of three services:

- **Golang application service**: This service builds the Golang application using the Dockerfile and runs it in a container. It exposes the application's port `8000` and connects to the `go-network` network. It also defines a health check to monitor the application's health. You have also used `healthcheck` to monitor the health of the application. The health check runs every 30 seconds and retries 5 times if the health check fails. The health check uses the `curl` command to check the `/health` endpoint of the application. Apart from the health check, you have also added a `develop` section to watch the changes in the application's source code and rebuild the application using the Docker Compose Watch feature.

- **Prometheus service**: This service runs the Prometheus server in a container. It uses the official Prometheus image `prom/prometheus:v2.55.0`. It exposes the Prometheus server on port `9090` and connects to the `go-network` network. You have also mounted the `prometheus.yml` file from the `Docker` directory which is present in the root directory of your project. The `prometheus.yml` file contains the Prometheus configuration to scrape the metrics from the Golang application. This is how you connect the Prometheus server to the Golang application.

    ```yaml
    global:
      scrape_interval: 10s
      evaluation_interval: 10s

    scrape_configs:
      - job_name: myapp
        static_configs:
          - targets: ["api:8000"]
    ```

    In the `prometheus.yml` file, you have defined a job named `myapp` to scrape the metrics from the Golang application. The `targets` field specifies the target to scrape the metrics from. In this case, the target is the Golang application running on port `8000`. The `api` is the service name of the Golang application in the Docker Compose file. The Prometheus server will scrape the metrics from the Golang application every 10 seconds.