What is Docker ?
Docker is a platform that allows you to easily develop, deploy, and run applications by using containers. Containers are a way to package software in a format that can run consistently on any system, ensuring that your application will always run the same, regardless of the environment it is running in.
To set up Docker, you’ll first need to install the Docker Engine on your system. Docker Engine is the underlying technology that runs containers. You can find the instructions for installing Docker Engine on the Docker website.
Docker Commands
Once you have Docker Engine installed, you can start using Docker by running Docker commands in a terminal or command prompt. Here are some of the most commonly used Docker commands:
docker run: Runs a command in a new container.docker start: Starts one or more stopped containers.docker stop: Stops one or more running containers.docker build: Builds an image from a Dockerfile.docker images: Lists images.
Docker with example:
Here’s an example of using Docker to run a simple Java application:
- Create a file named “Dockerfile” and add the following content to it:
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FROM openjdk:8-jdk-alpine COPY . /app WORKDIR /app RUN javac Main.java CMD ["java", "Main"] |
- Create a file named “Main.java” and add the following Java code to it:
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public class Main { public static void main(String[] args) { System.out.println("Hello, Docker!"); } } |
- Run the following command to build the Docker image:
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docker build -t my-java-app . |
- Finally, run the following command to run the Docker container:
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docker run my-java-app |
This will run the Java application inside a Docker container, and you should see the output “Hello, Docker!” printed to the console.
Note that this is just a simple example to demonstrate the basic usage of Docker with a Java application. In a real-world scenario, you would need to handle things like networking, volumes, and environment variables in a more sophisticated way.