Why does my Spring Boot App always shutdown immediately after starting?

Resolution: the app is not a webapp because it doesn’t have an embedded container (e.g. Tomcat) on the classpath. Adding one fixed it. If you are using Maven, then add this in pom.xml:

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>

For Gradle (build.gradle) it looks like

dependencies {
    compile 'org.springframework.boot:spring-boot-starter-web'
}