deploy spring boot on docker

Deploying a Spring Boot application on Docker involves several steps, from creating a Docker image to running the containerized application. Here’s a step-by-step guide to help you through the process.

Prerequisites

1. Docker Installed: Ensure Docker is installed on your system. You can download it from the Docker website.
2. Spring Boot Application: A Spring Boot application ready for deployment.
3. Maven or Gradle: Ensure you have either Maven or Gradle configured in your Spring Boot project.

Step 1: Create a Dockerfile

A Dockerfile is a script that contains a series of instructions on how to build a Docker image for your application.

1. Navigate to your Spring Boot project directory.

2. Create a Dockerfile in the root directory of your project:

   # Use an official Java runtime as a parent image FROM openjdk:17-jdk-alpine # Set the working directory in the container WORKDIR /app # Copy the project’s jar file into the container at /app COPY target/myapp.jar /app/myapp.jar # Expose the port your Spring Boot app runs on EXPOSE 8080 # Run the jar file ENTRYPOINT ["java", "-jar", "myapp.jar"]

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   # Use an official Java runtime as a parent image FROM openjdk:17-jdk-alpine   # Set the working directory in the container WORKDIR /app   # Copy the project’s jar file into the container at /app COPY target/myapp.jar /app/myapp.jar   # Expose the port your Spring Boot app runs on EXPOSE 8080   # Run the jar file ENTRYPOINT ["java", "-jar", "myapp.jar"]

   • Replace target/myapp.jar with the actual path to your JAR file.
   • If you’re using a different JDK version, replace openjdk:17-jdk-alpine with your desired base image.

Step 2: Build Your Application

1. Build the application JAR using Maven or Gradle.

   For Maven:

   mvn clean package

   1	mvn clean package

   For Gradle:

   ./gradlew build

   1	./gradlew build

2. Ensure the JAR file is generated in the target directory (for Maven) or build/libs directory (for Gradle).

Step 3: Build the Docker Image

1. Open a terminal in your project directory where the Dockerfile is located.

2. Build the Docker image using the following command:

   docker build -t my-spring-boot-app .

   1	docker build -t my-spring-boot-app .

   • -t my-spring-boot-app tags your Docker image with the name my-spring-boot-app.
   • The . at the end indicates that the Dockerfile is in the current directory.

Step 4: Run the Docker Container

1. Run the Docker container with the following command:

   docker run -p 8080:8080 my-spring-boot-app

   1	docker run -p 8080:8080 my-spring-boot-app

   • -p 8080:8080 maps port 8080 on your local machine to port 8080 on the Docker container.
   • my-spring-boot-app is the name of the image you just built.

2. Access your application by navigating to http://localhost:8080 in your web browser.

Step 5: Pushing to Docker Hub (Optional)

If you want to share your Docker image or deploy it to a cloud provider, you can push it to Docker Hub.

1. Log in to Docker Hub:

   docker login

   1	docker login

2. Tag your image for Docker Hub:

   docker tag my-spring-boot-app your-dockerhub-username/my-spring-boot-app

   1	docker tag my-spring-boot-app your-dockerhub-username/my-spring-boot-app

3. Push the image to Docker Hub:

   docker push your-dockerhub-username/my-spring-boot-app

   1	docker push your-dockerhub-username/my-spring-boot-app

4. Pull the image and run it on any machine with Docker:

   docker pull your-dockerhub-username/my-spring-boot-app docker run -p 8080:8080 your-dockerhub-username/my-spring-boot-app

   1 2	docker pull your-dockerhub-username/my-spring-boot-app docker run -p 8080:8080 your-dockerhub-username/my-spring-boot-app

Step 6: Clean Up (Optional)

To stop the running container:

To remove the container and image:

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Tips and Best Practices

• Multi-Stage Builds: For smaller image sizes, you can use multi-stage builds in your Dockerfile.

  # Build stage FROM maven:3.8.5-openjdk-17-slim AS build WORKDIR /app COPY . . RUN mvn clean package # Run stage FROM openjdk:17-jdk-alpine WORKDIR /app COPY --from=build /app/target/myapp.jar /app/myapp.jar EXPOSE 8080 ENTRYPOINT ["java", "-jar", "myapp.jar"]

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  # Build stage FROM maven:3.8.5-openjdk-17-slim AS build WORKDIR /app COPY . . RUN mvn clean package   # Run stage FROM openjdk:17-jdk-alpine WORKDIR /app COPY --from=build /app/target/myapp.jar /app/myapp.jar EXPOSE 8080 ENTRYPOINT ["java", "-jar", "myapp.jar"]

• Environment Variables: Use Docker environment variables for configuring your application dynamically.

• Docker Compose: Use Docker Compose to manage multi-container applications (e.g., app container + database container).

• CI/CD Pipelines: Integrate Docker build and deploy steps into your CI/CD pipeline using tools like Jenkins, GitHub Actions, or GitLab CI.

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By following these steps, you can easily deploy your Spring Boot application using Docker, making it more portable and easier to manage in different environments.