How to Host a Spring Boot Java Backend

You’ve written a robust Spring Boot application. But how do you get this Java server onto the internet without spending an afternoon configuring Tomcat on an Ubuntu machine?

The Power of Containers

The modern approach to deploying Java applications consists entirely of Docker. Spring Boot perfectly packages its own embedded Tomcat server into a runnable `.jar` file. Docker lets you package that JAR with a specific Java Runtime environment so it runs identically everywhere.

Step 1: Write a Dockerfile

Create a `Dockerfile` in the root of your project repository:

# Build stage using Maven or Gradle
FROM maven:3.8.5-openjdk-17 AS build
COPY src /home/app/src
COPY pom.xml /home/app
RUN mvn -f /home/app/pom.xml clean package -DskipTests

# Package stage
FROM openjdk:17-jdk-slim
COPY --from=build /home/app/target/demo-0.0.1-SNAPSHOT.jar /usr/local/lib/demo.jar
EXPOSE 8080
ENTRYPOINT ["java","-jar","/usr/local/lib/demo.jar"]

Step 2: Connect and Deploy

With this Dockerfile pushed to GitHub, simply link your repository to Remoud via the Dashboard. Remoud automatically parses the Dockerfile, builds your multi-stage container, and publishes your Spring Boot instance to an unmetered, SSL-secured domain.

Managing Application Properties

You can override Spring's `application.properties` cleanly by adding Environment Variables in the Remoud Dashboard, keeping your secrets injected safely at runtime.