Minimal Docker image using custom JRE

Category : Kubernetes | Sub Category : Kubernetes With Java | By Prasad Bonam Last updated: 2023-11-21 10:42:32 Viewed : 221

Creating a minimal Docker image for a Java application involves using a custom JRE (Java Runtime Environment) and optimizing the image to reduce its size. One popular choice for creating minimal Java images is to use AdoptOpenJDK with a base Alpine Linux image. The Alpine Linux distribution is known for its small size, making it a good choice for minimal Docker images.

Here is an example of a Dockerfile for creating a minimal Java image using AdoptOpenJDK and Alpine Linux:

DockerfileCopy code
# Use AdoptOpenJDK with Alpine Linux as the base image
FROM adoptopenjdk:11-jre-hotspot-alpine3.14

# Set the working directory
WORKDIR /app

# Copy the JAR file into the container
COPY target/your-application.jar .

# Specify the command to run your application
CMD ["java", "-jar", "your-application.jar"]

In this Dockerfile:

• adoptopenjdk:11-jre-hotspot-alpine3.14 is used as the base image. This base image contains only the minimal packages required to run Java applications, and it is based on Alpine Linux.

• The working directory is set to /app.

• The application JAR file (replace your-application.jar with the actual name of your JAR) is copied into the container.

• The CMD instruction specifies the command that will be executed when the container starts. In this case, it runs the Java application using the JAR file.

To build your minimal Docker image, use the following command:

bashCopy code
docker build -t your-image-name:tag .

Replace your-image-name:tag with the desired name and tag for your Docker image.

Building minimal Docker images is essential for reducing the image size, optimizing deployment speed, and minimizing the attack surface of your application. Using Alpine Linux as the base and AdoptOpenJDK helps achieve a balance between a small image size and a functional Java runtime environment.