docker-compose.yml

Overview

The [docker-compose.yml](/projects/291/68791) file defines and configures a multi-container Docker application environment specifically for the `api` service of the Bitcoincash project. This file leverages Docker Compose to simplify the orchestration of service containers, network configuration, and volume mounting, facilitating local development and testing of the Bitcoincash API.

In this context, the file sets up a single service named `api` that runs a Node.js-based backend using a pre-built Docker image. It integrates with Traefik as a reverse proxy for routing HTTP requests and enables live code reloading with `nodemon`. The configuration also connects the service to an external Docker network to allow communication with other related services or infrastructure components.

Detailed Explanation

Services Section

api Service

• Purpose:
  Hosts the Bitcoincash API backend service inside a Docker container.

• Configuration Details:

  • image: unchained-local-node
    Uses a custom Docker image named unchained-local-node which presumably contains the Node.js runtime and the application code environment.

  • env_file: .env
    Loads environment variables from a .env file located alongside the docker-compose.yml, allowing configuration parameters (e.g., database URLs, API keys) to be externalized.

  • labels:
    These labels configure Traefik, the reverse proxy/load balancer:

    • 'traefik.enable=true'
      Enables Traefik proxying for this container.

    • 'traefik.http.routers.bitcoincash-api.rule=Host(api.bitcoincash.localhost)'
      Routes HTTP requests with hostname api.bitcoincash.localhost to this service.

    • 'traefik.http.services.bitcoincash-api.loadbalancer.server.port=3000'
      Specifies that Traefik should forward traffic to container port 3000, where the Node.js server listens.

  • working_dir: /app/node/coinstacks/bitcoincash/api
    Sets the working directory inside the container, pointing to the Bitcoincash API source folder.

  • command: yarn nodemon
    Overrides the default container command to run yarn nodemon, which starts the API with automatic restart on code changes, supporting live development.

  • volumes:

    • ../../..:/app
      Mounts the host directory three levels up into /app inside the container, enabling live code syncing and access to the full project source.

  • networks:

    • bitcoincash
      Connects this container to the external Docker network named bitcoincash_default for inter-service communication.

Networks Section

• bitcoincash Network:
  Defines an external Docker network named bitcoincash_default. This network is expected to be created outside this Compose file (e.g., via docker network create bitcoincash_default) and enables the API container to communicate with other containers on the same network, such as database or caching services.

Usage Example

To start the API service with this configuration, the developer would run:

docker-compose up api

This command will:

• Pull or build the unchained-local-node image (if not present).

• Initialize the container with the working directory and mounted volumes.

• Start the Node.js API with nodemon for live reload.

• Connect the container to the bitcoincash_default network.

• Register the service with Traefik for proper HTTP routing.

Important Implementation Details

• Live Reloading:
  The use of nodemon through the command field facilitates real-time code changes without restarting containers manually, boosting developer productivity.

• Traefik Integration:
  Labels integrate tightly with Traefik's dynamic configuration, enabling hostname-based routing and load balancing without manual proxy setup.

• Volume Mounting:
  Mounting a relative path (../../..) to /app allows the container to run the code from the host machine, essential for local development but not recommended for production due to performance and security considerations.

• External Network Usage:
  The external network allows modular infrastructure scaling by enabling independent container lifecycle management and communication across multiple Docker Compose projects or containers.

Interaction with Other System Components

• Traefik Reverse Proxy:
  This file expects Traefik to be running as a gateway, handling incoming HTTP requests and forwarding them to the API container based on hostname rules.

• Project Source Code:
  The volume mount points to the main project directory, implying that source code management and updates are handled outside the container.

• Other Services on bitcoincash_default:
  By joining the external network, this API can communicate with other services such as databases, caches, or other API components, which are assumed to be configured elsewhere.

Visual Diagram

flowchart TD
    A[Host Machine] -->|Mount ../../.. to /app| B[API Container]
    B -->|Runs| C[yarn nodemon]
    B -->|Listens on port 3000| D[API Server]
    E[Traefik Proxy] -->|Routes Host api.bitcoincash.localhost| D
    B --- F[bitcoincash_default Network]
    F --> G[Other Services (DB, Cache, etc.)]

    style B fill:#f9f,stroke:#333,stroke-width:2px
    style E fill:#bbf,stroke:#333,stroke-width:2px
    style F fill:#dfd,stroke:#333,stroke-width:2px

**Diagram Explanation:**

• The host machine mounts the project code into the API container.

• The container runs the API server with nodemon.

• Traefik proxies incoming HTTP requests with the specified hostname to the container's port 3000.

• The container connects to an external Docker network allowing it to communicate with other backend services.

Summary

This [docker-compose.yml](/projects/291/68791) file is a focused development configuration for the Bitcoincash API service, enabling live reloading, Traefik-based routing, and networked communication. It is primarily targeted at local development environments, emphasizing ease of use and integration with the broader modular project architecture.