Spring Boot application.yml / application.yaml

1. Introduction

Spring Boot supports configuration using:

• application.properties

• application.yml / application.yaml

YAML files are used to define configuration in a structured and readable format.

2. Why Use application.yml

• Hierarchical structure

• Easy to read

• Less repetition

• Better for large applications

• Common in microservices

3. File Location

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src/main/resources

4. Server Configuration

Change default port:

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server:
  port: 8989

5. Application Name

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spring:
  application:
    name: my-app

6. Database Configuration

MySQL Example

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spring:
  datasource:
    url: jdbc:mysql://localhost:3306/mydb
    username: root
    password: 1234
    driver-class-name: com.mysql.cj.jdbc.Driver

H2 Database Example

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spring:
  datasource:
    url: jdbc:h2:mem:testdb
    username: sa
    password: ""
  h2:
    console:
      enabled: true

MongoDB Example

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spring:
  data:
    mongodb:
      uri: mongodb://localhost:27017/mydb

7. Eureka Server Configuration

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eureka:
  client:
    service-url:
      defaultZone: http://localhost:8761/eureka/
    register-with-eureka: true
    fetch-registry: true

8. application.yml vs application.properties

Format

• properties: key=value

• yaml: hierarchical

Readability

• properties: less readable for large config

• yaml: more readable

Structure

• properties: flat

• yaml: nested

Usage

• properties: simple configuration

• yaml: complex configuration

9. Key Points

• YAML uses indentation

• No semicolons or brackets

• Better for complex setups

• Widely used in microservices

10. Conclusion

• application.yml is modern and readable

• Preferred for large applications

• Helps organize configuration clearly