In this article, we will discuss application.yml vs bootstrap.yml in Spring Boot and how application.yml or bootstrap.yml are useful in Application development. The application.yml is auto-configured by the Spring Boot framework to handle the development but for the bootstrap.yml we need to configure it externally in Spring Boot. The application.yml or application.properties file configures the application context and bootstrap.yml file is used to configure the bootstrap context.

Usage of application.yml

• This is the main configuration file used by the Spring Boot application.
• It contains configuration properties specific to the application.
• Properties are defined here as loaded after bootstrap.yml is loaded.

Usage of bootstrap.yml

• It is particularly used for setting external configurations like Environment-specific properties.
• Properties are defined here as loaded before application.yml is loaded.
• It is mostly used in microservices architectures to manage independently from the application code.

Example:

Below we provide example configuration properties in both application.yml and bootstrap.yml in Spring Boot.

• It is very useful to understand the difference.
• And we provide the configuration details only.
• After creating Spring Boot project in resource folder, we need to create application.yml and bootstrap.yml files then define your own configuration properties for the project.

Note: Below we provide example structure of application.yml and bootstrap.yml, based on your project, you need modify it.

application.yml:

spring:
  application:
    name: my-service
  datasource:
    url: jdbc:mysql://localhost:3306/mydatabase
    username: myuser
    password: mypassword
  logging:
    level:
      org.springframework: INFO
      com.example: DEBUG
  security:
    oauth2:
      client:
        clientId: my-client-id
        clientSecret: my-client-secret
        accessTokenUri: http://auth-server/oauth/token
        userAuthorizationUri: http://auth-server/oauth/authorize
  cache:
    caffeine:
      spec: maximumSize=100,expireAfterAccess=300s
  messaging:
    kafka:
      bootstrap-servers: kafka:9092
      consumer:
        groupId: my-group
  myapp:
    greeting: Hello from MyApp!

bootstrap.yml:

spring:
  profiles:
    active: dev
  cloud:
    config:
      uri: http://config-server:8888
      profile: dev
  retry:
    maxAttempts: 3
    initialInterval: 1000
    multiplier: 1.5
    maxInterval: 5000
  feign:
    client:
      config:
        default:
          connectTimeout: 5000
          readTimeout: 5000

Difference between application.yml and bootstrap.yml