Managing Environment-Specific application.properties Files

Spring Boot allows the use of multiple application.properties files to manage different environments such as local development, Docker deployment, and testing. This document explains how to configure and structure application.properties files for each environment and utilize profiles to switch between them.

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1. Local Development Configuration

This configuration is used during local development. It connects to a MySQL database hosted locally (e.g., via Docker) and uses sensitive credentials stored in a .env file.

application-local.properties

# Import configuration from .env
spring.config.import=optional:file:.env[.properties]

# Database configuration for MySQL (hosted locally)
spring.datasource.url=jdbc:mysql://localhost:3307/crowdfund_db
spring.datasource.username=${MYSQL_USERNAME}
spring.datasource.password=${MYSQL_PASSWORD}
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver

# JPA configuration (Hibernate)
spring.jpa.hibernate.ddl-auto=update
spring.jpa.open-in-view=false
spring.jpa.show-sql=true
spring.jpa.properties.hibernate.connection.autocommit=false

# JWT secret
jwt.secret=${JWT_SECRET}

Key Points:

• Database: Connects to a locally running MySQL database on port 3307.
• Environment Variables: Credentials (MYSQL_USERNAME, MYSQL_PASSWORD, JWT_SECRET) are loaded from an .env file.
• Hibernate: Automatically updates the schema and logs SQL queries for debugging.

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2. Docker Deployment Configuration

This configuration is tailored for a Dockerized environment, where the application communicates with other containers (e.g., a MySQL container).

application-docker.properties

# Import configuration from .env
spring.config.import=optional:file:.env[.properties]

# Database configuration for MySQL (hosted in Docker)
spring.datasource.url=jdbc:mysql://raisehub_database:3306/crowdfund_db
spring.datasource.username=${MYSQL_USERNAME}
spring.datasource.password=${MYSQL_PASSWORD}
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver

# JPA configuration (Hibernate)
spring.jpa.hibernate.ddl-auto=update
spring.jpa.open-in-view=false
spring.jpa.show-sql=true
spring.jpa.properties.hibernate.connection.autocommit=false
spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.MySQL8Dialect

# Server configuration
server.port=8080

# Connection pool settings
spring.datasource.hikari.maximum-pool-size=10
spring.datasource.hikari.connection-timeout=30000
spring.datasource.hikari.idle-timeout=600000
spring.datasource.hikari.max-lifetime=1800000

# Logging configuration
logging.level.root=INFO
logging.level.org.springframework=DEBUG
logging.file.name=/tmp/spring-docker.log

# JWT secret
jwt.secret=${JWT_SECRET}

Key Points:

• Database: Connects to a MySQL container (raisehub_database) via the Docker network.
• Connection Pooling: Tuned for containerized environments using HikariCP.
• Logging: Logs application events to /tmp/spring-docker.log.
• Port: The application listens on port 8080.

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3. Testing Configuration

This configuration is used for unit tests and integration tests. It relies on an in-memory H2 database for fast and isolated testing.

application-test.properties

# H2 in-memory database configuration
spring.datasource.url=jdbc:h2:mem:public
spring.datasource.driverClassName=org.h2.Driver
spring.datasource.username=sa
spring.datasource.password=password
spring.jpa.database-platform=org.hibernate.dialect.H2Dialect
spring.jpa.hibernate.ddl-auto=create
spring.jpa.show-sql=true
spring.jpa.defer-datasource-initialization=true
spring.sql.init.mode=always

# JWT secret
jwt.secret=${JWT_SECRET}

Key Points:

• In-Memory Database: H2 is used for lightweight and temporary database operations during testing.
• Schema Initialization: The schema is recreated for every test run (ddl-auto=create).
• Fast Execution: No external dependencies; everything runs in memory.

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4. Switching Between Configurations

Using Spring Profiles

Spring Boot profiles allow you to load different configuration files based on the active profile. Profile-specific files must follow the naming convention application-{profile}.properties.

1. Set Active Profile:

   • Use the spring.profiles.active property to specify the profile:

     spring.profiles.active=local
   • In Docker, set spring.profiles.active=docker.

2. Profile-Specific Files:

   • application-local.properties for local development.
   • application-docker.properties for Docker environments.
   • application-test.properties for testing.

How Profiles Work:

• The spring.profiles.active property determines which profile-specific file Spring Boot uses.
• For example:
  • spring.profiles.active=local loads application-local.properties.
  • spring.profiles.active=docker loads application-docker.properties.
  • Default behavior loads the base application.properties if no profile is specified.

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Summary

Environment	File Name	Key Configuration
Local Development	application-local.properties	Connects to a locally hosted MySQL database.
Docker Deployment	application-docker.properties	Uses Dockerized MySQL database.
Testing	application-test.properties	Uses an in-memory H2 database for fast and isolated testing.

This setup ensures that the application is flexible and maintains environment-specific configurations in an organized and maintainable way.