Learn how to override and customize Spring Boot’s default configuration using properties, custom beans, profiles, and auto-configuration exclusions.

Ramesh Fadatare

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2 min read

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Mar 25, 2025

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Introduction

Spring Boot offers opinionated defaults that make setup fast. But what if you need different settings?

The good news: Spring Boot lets you override or extend these defaults easily — without disabling everything.

Let’s explore 5 common and powerful ways to customize Spring Boot’s default configuration.

🔹 1. Customize with application.properties or application.yml

This is the most common way to tweak default values.

🔧 Example: Change server port

server.port=9090

🔧 Example: Configure datasource

spring.datasource.url=jdbc:mysql://localhost:3306/mydb
spring.datasource.username=root
spring.datasource.password=secret

📌 Use this for:

• Server settings
• DB connections
• Logging
• Caching
• JPA & Hibernate settings

🗂️ You can also use application.yml if you prefer YAML syntax.

🔹 2. Customize with Profiles (application-dev.properties, etc.)

You can define different configs for different environments using Spring Profiles.

🔧 Example:

• application-dev.properties for dev
• application-prod.properties for production

Then activate the profile in your application.properties:

spring.profiles.active=dev

Or use CLI:

java -jar app.jar --spring.profiles.active=prod

🔁 Great for customizing behavior by environment.

🔹 3. Override AutoConfigured Beans

Spring Boot only configures beans if they don’t already exist (thanks to @ConditionalOnMissingBean).