Docker Workflow

Docker is a containerization platform that allows you to package an application and its dependencies into a standardized unit called a container. This container can then be run consistently across different environments, providing a predictable and isolated environment for your application to run.

How Docker Work

Step 1: Develop and build your application: Start by developing your application code using your preferred programming language and tools. Once you have a working application, you’ll need to create a Dockerfile. A Dockerfile is a text file that contains a set of instructions for building a Docker image. It defines the base image, adds any necessary dependencies, copies your application code into the image, and specifies the commands to run when the container is started.

Step 2: Build a Docker image: Use the Docker CLI (Command Line Interface) or a build tool like Docker Compose or a CI/CD (Continuous Integration/Continuous Deployment) system to build a Docker image based on your Dockerfile. The Docker image is a standalone package that includes your application code, runtime environment, and any required dependencies.

$ docker build -t myapp:latest .

The above command builds an image using the Dockerfile located in the current directory represented by (`.`) and tags it as `myapp:latest`.

Step 3: Run Docker containers: Once you have a Docker image, you can create and run Docker containers from it. Containers are instances of Docker images that can be started, stopped, and managed independently. You can run containers locally on your development machine or deploy them to a production environment.

$ docker container run -d -p 8080:80 myapp:latest

The docker container run -d -p 8080:80 myapp:latest command starts a container based on the `myapp:latest` image, maps port 8080 on the host to port 80 inside the container (`-p 8080:80`), and runs the container in detached mode (`-d`). You can use ‘-P ’ which will mount a random port to the hsot inside the container.

Step 4:Manage Docker containers: Docker provides a set of commands to manage running containers. You can view running containers, stop containers, start stopped containers, and remove containers when they are no longer needed.

 $ docker ps      
 $ docker ps -a       
 $ docker stop <container_id>
 $ docker start <container_id>
 $ docker rm <container_id>

# The `docker ps` command lists all running containers, 
# `docker ps -a` show all containers (default shows just running)
# `docker stop` stops a running container, 
# `docker start` starts a stopped container
# `docker rm` removes a container.

When you run dokcer container --help you will see all the ways you can manage your command.

Step 5: Use Docker Compose for multi-container applications: Docker Compose is a tool for defining and running multi-container Docker applications. It uses a YAML file to define the services, networks, and volumes required for your application. With Docker Compose, you can start and stop multiple containers at once, define network connections between them, and manage their configurations.

Step 6: Publish and distribute Docker images: Docker images can be published to a registry, such as Docker Hub or a private registry. Publishing your images allows others to use them or deploy them to different environments. You can also distribute your images by sharing the Docker image file or pushing it to a version control system.

 $ docker push myregistry/myapp:latest
This command pushes the `myapp:latest` image to the `myregistry` registry.

Step 7: Update and iterate: As you continue to develop and enhance your application, you can iterate on your Docker image by updating the Dockerfile and rebuilding the image. This allows you to easily distribute and deploy new versions of your application.

Conclusion:

Docker’s methodology for containerizing and deploying applications is quite powerful. Its workflow entails developing and building your application, creating Docker images with Dockerfiles, executing containers based on those images, controlling containers with Docker commands, and, for multi-container applications, possibly utilizing Docker Compose.

Docker makes it easier to package apps and their dependencies, assuring consistency and portability across environments. Docker allows developers to concentrate on developing code while knowing that their applications will execute safely and consistently, regardless of the underlying infrastructure. Docker’s workflow speeds the process of constructing, running, and managing containers, making it a vital tool in modern software development and deployment, whether for local development, testing, or production deployment.