Micro services for noobs

This repo contains the resources used during a workshop with my students to provide a minimal demonstration of containerization and the use of microservices.

This project illustrate the use of docker with Dockerfiles and docker-compose.yml

Before or after reading

For a better understanding of this very minimal demo project take a look at these ressources :

• https://microservices.io/patterns/index.html : This site is not at all appealing, but these pages on various types of open microservices patterns will allow you to discover new terms you might not know

• https://docker-curriculum.com/ : Docker for beguinners

Requirements

• Install docker : https://docs.docker.com/engine/install/

Project Structure

• ./serviceA/: Contains the files for Service A
• ./serviceB/: Contains the files for Service B
• docker-compose.yml: Docker Compose configuration file

Dockerfiles

Service A

FROM node:18
WORKDIR /app
COPY package*.json ./
RUN npm install
COPY . .
EXPOSE 3000
CMD [ "node", "server.js" ]

Service B

FROM node:18
WORKDIR /app
COPY package*.json ./
RUN npm install
COPY . .
EXPOSE 3001
CMD [ "node", "server.js" ]

These Dockerfiles define the environment, copy the necessary files, and run the servers.

docker-compose.yml

services:
  service-a:
    build: './serviceA'
    ports:
      - "3000:3000"
    networks:
      - some-net
      
  service-b:
    build: './serviceB'
    ports:
      - "3001:3001"
    networks:
      - some-net

networks:
  some-net:
    driver: bridge

This file orchestrates the services and defines a shared network some-net.

Inter-Service Communication

In serviceA/server.js, Service A can communicate with Service B using:

await fetch("http://service-b:3001")

This is possible because both services are on the same network defined in docker-compose.yml.

graph TD;
    A[service-a] --> | fetch service-b:3001 | B[service-b];
    B --> | Responds | A;

Loading

Execution

Run the following command to start the services:

docker-compose up --build

Shutdown

To shut down the services, use:

docker-compose down

Demo

When you call : GET http://localhost:3000/check-service-b

It should respond with 'ok'

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That's all folks !