EMS

Multi-Service Application with Kafka and Zookeeper

This repository contains a multi-service application using Docker Compose, featuring the following components:

• Zookeeper: Manages the Kafka cluster.
• Kafka: Messaging broker for communication between microservices.
• Auth Service: Handles user authentication and authorization.
• User Management Service: Manages user data and profiles.

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Prerequisites

Before running the application, ensure you have the following installed:

1. Docker: Install Docker
2. Docker Compose: Install Docker Compose

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Services Overview

1. Zookeeper

• Purpose: Manages the Kafka cluster's metadata.
• Port: 2181
• Image: confluentinc/cp-zookeeper:latest

2. Kafka

• Purpose: Message broker used for communication between microservices.
• Port: 9092
• Image: confluentinc/cp-kafka:latest

3. Auth Service

• Purpose: Handles user authentication and authorization.
• Port: 9000
• Custom Image: viraj179/auth-service:latest

4. User Management Service

• Purpose: Manages user profiles and data.
• Port: 9010
• Custom Image: viraj179/user-management-service:latest

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How to Run

Step 1: Clone the Repository

Clone the repository and navigate to the project directory:

git clone https://github.com/SoftGrid2/ems.git
cd ems

docker pull confluentinc/cp-zookeeper:latest
docker pull confluentinc/cp-kafka:latest
docker pull viraj179/nlss-auth-service:latest
docker pull viraj179/nlss-user-management-service:latest

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## Step 1: Start the application
docker-compose up -d

### Step 2: Verify Running Containers
docker ps

### Step 3: You should see the following containers:

zookeeper
kafka
auth-service
user-management

### Notes
Ensure Zookeeper starts before Kafka.
Kafka must be running for auth-service and user-management-service to work properly.
The services communicate internally through the kafka-network defined as a bridge network.

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Querying Databases in Docker Containers for auth-service and user-management

This guide provides steps to query databases running in Docker containers for both auth-service and user-management services.

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Prerequisites

• Docker and Docker Compose installed on your machine.
• PostgreSQL client installed locally (optional for direct host access).
• Databases auth-service and user-management running in Docker containers.

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Querying the auth-service Database

Accessing the Docker Container

1. Find the running container for auth-service:

   docker ps

2. Access the PostgreSQL database inside the auth-service container:

   docker exec -it postgres-auth-service psql -U postgres -d auth-service

3. Verify tables in the database:

   \dt

Common SQL Queries

• View data in the users table:

  SELECT * FROM users LIMIT 10;

• Count total users:

  SELECT COUNT(*) FROM users;

• Insert a sample user:

  INSERT INTO users (email, password, role, name, created_at, updated_at)
  VALUES ('example@example.com', 'securepassword', 'Admin', 'John Doe', NOW(), NOW());

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Querying the user-management Database

Accessing the Docker Container

1. Find the running container for user-management:

   docker ps

2. Access the PostgreSQL database inside the user-management container:

   docker exec -it postgres-user-management psql -U postgres -d user-management

3. Verify tables in the database:

   \dt

Common SQL Queries

• View data in the users table:

  SELECT * FROM users LIMIT 10;

• Insert a sample user:

  INSERT INTO users (email, password, name, created_at, updated_at)
  VALUES ('jane.doe@example.com', 'securepassword', 'Jane Doe', NOW(), NOW());

• Delete a user by ID:

  DELETE FROM users WHERE id = 1;

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Tips for Managing Databases

• Exporting a Database:

  docker exec -it postgres-auth-service pg_dump -U postgres auth-service > auth-service.sql

• Restoring a Database:

  docker exec -i postgres-auth-service psql -U postgres auth-service < auth-service.sql

• Backup for user-management:

  docker exec -it postgres-user-management pg_dump -U postgres user-management > user-management.sql

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Troubleshooting

• Error: Relation does not exist

  • Verify the correct database is selected.
  • Check if the tables were created properly using \dt.

• Connection Issues

  • Ensure environment variables (DB_HOST, DB_PORT, DB_USER, DB_PASSWORD, DB_NAME) are correctly set.
  • Restart containers to apply changes:

    docker-compose restart

• Check Logs

  docker logs postgres-auth-service
  docker logs postgres-user-management

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Useful Commands

• List all databases:

  \l

• Describe a table:

  \d table_name

• Exit PostgreSQL:

  \q

• Exit docker_container:

  exit

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