> For the complete documentation index, see [llms.txt](https://docs.hackerspot.net/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.hackerspot.net/cheatsheets/cloud-tools/docker.md). # Docker ## Docker CLI ### Basic Commands * **docker --version** * Check Docker version. ```sh docker --version ``` * **docker info** * Display system-wide information. ```sh docker info ``` * **docker help** * Get help on Docker commands. ```sh docker help ``` ### Images * **docker images** * List all Docker images. ```sh docker images ``` * **docker pull \[image]** * Pull an image from a registry. ```sh docker pull ubuntu:latest ``` * **docker rmi \[image\_id]** * Remove a Docker image. ```sh docker rmi ubuntu:latest ``` ### Containers * **docker ps** * List running containers. ```sh docker ps ``` * **docker ps -a** * List all containers (running and stopped). ```sh docker ps -a ``` * **docker run \[options] \[image]** * Run a command in a new container. ```sh docker run -it ubuntu:latest /bin/bash ``` * **docker stop \[container\_id]** * Stop a running container. ```sh docker stop [container_id] ``` * **docker start \[container\_id]** * Start a stopped container. ```sh docker start [container_id] ``` * **docker restart \[container\_id]** * Restart a container. ```sh docker restart [container_id] ``` * **docker rm \[container\_id]** * Remove a stopped container. ```sh docker rm [container_id] ``` ### Networks * **docker network ls** * List all networks. ```sh docker network ls ``` * **docker network create \[network\_name]** * Create a new network. ```sh docker network create my_network ``` * **docker network rm \[network\_name]** * Remove a network. ```sh docker network rm my_network ``` ### Volumes * **docker volume ls** * List all volumes. ```sh docker volume ls ``` * **docker volume create \[volume\_name]** * Create a new volume. ```sh docker volume create my_volume ``` * **docker volume rm \[volume\_name]** * Remove a volume. ```sh docker volume rm my_volume ``` ### Docker Compose * **docker-compose up** * Create and start containers. ```sh docker-compose up ``` * **docker-compose down** * Stop and remove containers, networks, images, and volumes. ```sh docker-compose down ``` * **docker-compose build** * Build or rebuild services. ```sh docker-compose build ``` ### Inspect and Logs * **docker inspect \[container\_id]** * Return low-level information on Docker objects. ```sh docker inspect [container_id] ``` * **docker logs \[container\_id]** * Fetch the logs of a container. ```sh docker logs [container_id] ``` ### Clean Up * **docker system prune** * Remove all unused containers, networks, images (both dangling and unreferenced), and optionally, volumes. ```sh docker system prune ``` * **docker container prune** * Remove all stopped containers. ```sh docker container prune ``` * **docker volume prune** * Remove all unused volumes. ```sh docker volume prune ``` * **docker image prune** * Remove unused images. ```sh docker image prune ``` This cheat sheet covers the basic and most commonly used Docker commands to get you started. Feel free to ask if you need more details or advanced commands! ## Creating a Dockerfile A Dockerfile is a text file that contains a series of instructions on how to build a Docker image. Here's a basic overview and examples of common Dockerfile instructions: ### Basic Structure of a Dockerfile 1. **FROM** * Specifies the base image. ```Dockerfile FROM ubuntu:latest ``` 2. **MAINTAINER** * Sets the author field of the generated images. ```Dockerfile MAINTAINER Your Name ``` 3. **RUN** * Executes commands in a new layer on top of the current image. ```Dockerfile RUN apt-get update && apt-get install -y nginx ``` 4. **COPY** * Copies files from the host machine to the Docker image. ```Dockerfile COPY ./localfile /path/in/container ``` 5. **ADD** * Copies files/directories from the host machine to the Docker image, and also supports extracting tar files. ```Dockerfile ADD ./localfile.tar /path/in/container ``` 6. **CMD** * Specifies the command to run within the container. ```Dockerfile CMD ["nginx", "-g", "daemon off;"] ``` 7. **ENTRYPOINT** * Sets a default application to be used every time a container is created with the image. ```Dockerfile ENTRYPOINT ["nginx", "-g", "daemon off;"] ``` 8. **EXPOSE** * Informs Docker that the container listens on the specified network ports at runtime. ```Dockerfile EXPOSE 80 ``` 9. **ENV** * Sets environment variables. ```Dockerfile ENV ENVIRONMENT production ``` 10. **VOLUME** * Creates a mount point with the specified path and marks it as holding externally mounted volumes from the native host or other containers. ```Dockerfile VOLUME /data ``` ### Example Dockerfile Here's an example Dockerfile for a simple web server using Nginx: ```Dockerfile # Use the official Nginx image from the Docker Hub FROM nginx:latest # Set the maintainer label MAINTAINER Your Name # Copy custom configuration file from the host to the container COPY nginx.conf /etc/nginx/nginx.conf # Copy the content of the website to the container COPY ./html /usr/share/nginx/html # Expose port 80 to the host EXPOSE 80 # Start Nginx when the container launches CMD ["nginx", "-g", "daemon off;"] ``` #### Building and Running the Docker Image 1. **Build the Docker Image** * Use the `docker build` command to create an image from the Dockerfile. ```sh docker build -t my-nginx-image . ``` 2. **Run the Docker Container** * Use the `docker run` command to start a container from the image. ```sh docker run -d -p 80:80 my-nginx-image ``` #### Best Practices * **Keep Dockerfile Instructions Ordered**: Use a logical order such as `FROM`, `MAINTAINER`, `RUN`, `COPY`, `CMD`. * **Use .dockerignore**: Create a `.dockerignore` file to exclude files and directories from the build context to reduce the size of the image. * **Minimize Layers**: Combine multiple `RUN` commands to reduce the number of layers. * **Leverage Caching**: Order the instructions to leverage Docker’s build cache. This should give you a good starting point for creating your own Dockerfiles! If you have any specific questions or need further details, feel free to ask.