Play Microservices: Integration via docker-compose

This is the 8th part of a series of articles under the name "Play Microservices". Links to other parts:
Part 1: Play Microservices: Bird's eye view
Part 2: Play Microservices: Authentication
Part 3: Play Microservices: Scheduler service
Part 4: Play Microservices: Email service
Part 5: Play Microservices: Report service
Part 6: Play Microservices: Api-gateway service
Part 7: Play Microservices: client-web service
Part 8: You are here
Part 9: Play Microservices: Security

The source code for the project can be found here:

Contents:

• Summary
• Tools
• Integration via Docker-compose
• To do

Summary

In the parts 1 to 7, we have developed our microservice application services independently. Those services are:

• Auth service (plus a database and a cache service)
• Job Scheduler service (plus a database, a kafka broker and a database for kafka broker)
• Email job executor service
• Report service (plus a database, a kafka broker and a database for kafka broker)
• An api-gateway service which acts as an entry-point to all other services.
• A client-web service

Now it's time to bring everything together. But before, lets have a look at the tools we need.

Tools

The tools required In the host machine:

• Docker: Containerization tool
• Git

Integration via Docker-compose

If you have followed the previous sessions, you should now have the following folder structure for all our services.

• Inside play-microservices folder, create a file named .env and set the contents to:

AUTH_SERVICE_PORT=9001
AUTH_POSTGRES_PORT=5432
AUTH_REDIS_PORT=6379
ZOOKEEPER_PORT=2181
KAFKA1_PORT=9092
SCHEDULER_MONGODB_PORT=27017
SCHEDULER_SERVICE_PORT=9002
EMAIL_SERVICE_PORT = 9003
POSTFIX_PORT=25
REPORT_SERVICE_PORT = 9004
REPORT_MONGODB_PORT=27018
API_GATEWAY_PORT=5010
CLIENT_PORT = 3000

• This file make it easier for us to handle the ports used by different services.
• Now, let's create a file called docker-compose.yml inside the play-microservices folder. This file will be used to integrate all the services. The contents of the docker-compose file can be found here.

Some notes on the docker-compose.yml file

As depicted in the services diagram, the services exhibit a hierarchical dependency tree. Therefore, inside the docker-compose file, we need to orchestrate the services in such a way that when a service starts, its dependencies are started and running in advance. To achieve this, we use healthcheckof docker compose. for example, for auth-db, which is a postgres service, for the healthcheckpart we have:

    healthcheck:
      test: ["CMD-SHELL", "pg_isready"]
      interval: 10s
      timeout: 1s
      retries: 5

• Auth service has dependency to auth-db service. For the depends_on condition we have:

    depends_on:
      auth-db:
        condition: service_healthy

• Seting condition to service_healthy guarantee that auth service will not run unless the auth-db is ready and running.
• We have other healthcheck definitions for zookeeper, kafka and mongodb services.
• One other thing to consider in our docker-compose file is the secrets. Each service may have a secret that need to be passed to other services. We use docker-compose secrets capability. When we define a secret for a service, Docker will create a file for that secret inside the container at /run/secrets/secret-name path. for example, We have defined a secret for auth-access-public-key. We pass this secret to other services that may need authentication service public key for verifying tokens signed by authentication service.

secrets:
  auth-access-public-key:
    file: auth/auth-service/keys/access_token.public.pem

• Open a terminal, cd to play-microservices folder and run docker-compose up -d --build. Wait until all services run. Go to http://localhost:3000/ and voila! Our application is ready to be tested.

To do

• deploy to a CI/CD environment via Jenkins
• Add and run tests