Docker Commands

Docker Commands

==========================================
              Docker Commands
==========================================

1. docker --version
   - Check version.

2. docker images
   - List all Docker images.

3. docker ps
   - List running containers.

4. docker pull {name}:{tag}
   - Pull an image from a registry.

5. docker run {name}:{tag}
   - Creates a container from a given image and starts it.

6. -d or --detach
   - Runs the container in the background and prints the container ID.

7. docker logs {container}
   - View logs from the service running inside the container
     (which are present at the time of execution).

8. docker stop {container}
   - Stop one or more running containers.

9. -p or --publish
   - Publish a container's port to the host.
     -p {HOST_PORT}:{CONTAINER_PORT}

10. -a or --all
    - List all containers (stopped and running).

11. docker start {container}
    - Start one or more stopped containers.

12. --name
    - Assign a name to the container.

==========================================
       Structure of a Dockerfile
==========================================

▶ **Linux operating system**  
▶ **JDK21 installed**  
▶ **Copy application files** from the host into the container.  
▶ **Executing commands**  

- **FROM**  
  Build this image from the specified base image.

- **RUN**  
  Execute any command in a shell inside the container environment.

- **COPY**  
  Copies files or directories from `<src>` and adds them to the container filesystem at `<dest>`.  
  Example: COPY `<src>` on our machine → `<dest>` in the container.

- **WORKDIR**  
  Sets the working directory for all following commands.  
  Example: Like changing into a directory using `cd...`.

- **CMD**  
  The instruction to be executed when a Docker container starts.  
  - There can only be one `CMD` instruction in a Dockerfile.  
  - Example: CMD ["command", "parameter"]

==========================================
         Docker Image Build Command
==========================================

1. docker build {path}
   - Builds a Docker image from a Dockerfile.

2. -t or --tag
   - Sets a name and optionally a tag in the `name:tag` format.

==========================================
         Example for Dockerfile
==========================================

▶ **Linux operating system**  
   Example:  
   FROM ubuntu:20.04  

▶ **JDK21 installed**  
   Example:  
   RUN apt-get update && apt-get install -y openjdk-21-jdk

▶ **Copy application files** from the host into the container.  
   Example:  
   COPY ./app /usr/local/app

▶ **Executing commands**  
   Example:  
   RUN cd /usr/local/app && java -jar myapp.jar