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

java

interview-preparation

best-practices

debugging

byNikita Barsukov·Nov 20, 2024

To quickly address this, ensure your spring-boot-starter-web dependency is present in your pom.xml or build.gradle:

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

Make sure there's nothing in your application properties that's telling your server to do a vanishing act, like server.port=-1. If we still can't stop the disappearing act, throw some duct tape on it with a CommandLineRunner:

@Bean
public CommandLineRunner applicationRunner() {
    return args -> {
        System.out.println("Application's still here, but you're chasing your tail...");
        CountDownLatch hold = new CountDownLatch(1);
        hold.await();  // App: "I shall not pass... away"
    };
}

For now, this can at least prevent the context from biting the dust and may spotlight the real culprit.

Keeping your dependencies in check

Interconflicting dependencies or a misconfigured Maven/Gradle setup could be the villain behind your app's abrupt exits. Make sure there is harmony in your dependencies and correct scoping for the web dependencies in your mighty build.gradle:

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

Also, watch out for any unintended exclusions, like excluding the poor spring-boot-starter-tomcat, which may lead to your app taking the fall:

<exclusions>
    <exclusion>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-tomcat</artifactId>
    </exclusion>
</exclusions>

Save some data lives by removing such exclusions, so your embedded container can live long and prosper.

Don't overlook that pesky spring.main.web-application-type setting in your properties; make sure it's not planning any sabotage and is set right for your app mission type.

Debugging tools and best practices

Everyone's best friend, debugging! Leverage what IDEs offer us, utilize IntelliJ IDEA to easily manage your dependencies and Spring Boot DevTools to avoid unnecessary development heartaches. Still no luck? Purge your local Maven repository or generate a clean build (a fresh start does wonders!) from start.spring.io.

The error might be crying out loud in the build output; don't ignore crying errors!

Configs and settings: a snake in the grass

Certain configuration settings like server.port = -1 can be the silent app killer you never suspected. Make sure none of your property settings are pulling the rug from under your app. Adjust as needed for peaceful coexistence!

Plausible reasons and remedies for a flighty app

Compatibility: Friends or Foes?

Friends don't let friends use incompatible dependencies. A mismatch can lead to your app retiring early. Keep versions in sync across your pom.xml or build.gradle:

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
    <version>2.5.0</version>
</dependency>

Application Runners and Context Loaders: Your Silent Protectors

Beyond our duct tape fix CommandLineRunner, ApplicationRunner can offer insights and stave off premature application exits. These can be especially handy to the Caped Crusader inside every developer, helping him debug startup issues or ensure the ApplicationContext loads without a hitch.

Finessing Troubleshooting

Read Error Logs: They're almost confessions from your app on what's going wrong.
Simulate Environment: It's like a dress rehearsal but for your app's big day.
Community Knows Best: Forums like Stack Overflow and the Spring community are like the Avengers assembling to help you out.

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