Docker: a Container Management Tool

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Are you a developer? And are you worried about the system that will be running on? Take a deep breath and calm down, use the ✨Docker✨

What is Docker?

Docker is a tool designed to make it easy to build, deploy, and run applications using containers. The container allows the developer to package the application with all its parts, such as libraries and other dependencies, and implement it as a single package. This means that developers can focus on writing code without worrying about the system that will eventually run it. It also allows them to start by using one of the thousands of programs already designed to run in Docker containers as part of their application.

What is Container?

Container is an OS virtualization that can wrap an application with its dependencies and environment. Each of these containers has an isolated process so that it doesn’t interfere with the host OS or other containers. Containers provide a highly efficient and highly detailed mechanism for combining software components into application types to keep those software components updated and maintained.

How to use Docker?

Here are several steps that must be passed.

1. Docker Image
   the file that contains guides and information for building a container.
2. Container
   environment or environment for application packaging needs that include system tools, code, runtime, and configuration.
3. Docker Client
   a place where users can send commands such as the Docker run, pull, and build to the Docker Daemon.
4. Docker Host
   responsible for receiving commands from the Docker Client
5. Docker Engine Rest API
   used for interaction with the Docker Daemon
6. Docker Hub
   a service that allows sharing Container Image with the team.
7. Docker Daemon
   responsible for managing Docker Image, Container, Storage Volume and Network.
8. Docker Registry
   a place to store the Docker image which will give the output according to the given command.

Docker architecture — https://docs.docker.com/get-started/overview/

Docker uses a client-server architecture. The Docker client talks to the Docker daemon, which does the heavy lifting of building, running, and distributing your Docker containers. Docker clients and daemons communicate using the REST API, via a UNIX socket or network interface. The Docker client and daemon can run on the same system, or you can connect the Docker client to a remote Docker daemon. Another Docker client is Docker Compose, which lets you work with applications that are composed of a collection of containers.
The Docker daemon will execute commands by managing objects such as images, containers, etc.

Docker Implementation

In PPL projects, my team uses docker to make our work easier. The first step I did was to install the Docker Client. What we need to do next is to create a Dockerfile. Here is the Dockerfile in our PPL project.

Dockerfile

The command beside basically tells docker to :

• FROM — Create an image from a Python 3.8 image
• WORKDIR — Change the working directory to $DockerHOME
• ENV — Set the environment variables
• RUN — Install dependencies
• COPY — Copy the whole project to docker home directory
• EXPOSE — Port where the Django app runs

Dockerfile.web

Next up is Dockerfile.web which sets up the environment and ensures that the Heroku container will do the python commands (makemigrations, migrate, and then runserver).

Update your GitLab configuration to include the docker image. Below is an example of our GitLab configuration for a docker image.

There are common functions that Docker has:

1. Supporting Developer Productivity

The first function is to be able to support performance in carrying out the stages of product application development effectively and achieve optimal production targets. The use of this platform makes it easier to run multiple services at once and is suitable for working on medium to upper-scale projects.

2. Simple Configuration Stage

Docker has the same advantages as virtual machines in general but does not take up the overhead. The existence of a simple configuration process in many environments is able to separate the infrastructure requirements for these applications.

3. Enable Portability

Docker containers run on any machine that supports a container runtime environment so that the application environment and the underlying operating environment can be kept clean and minimal. You can easily move container-based applications from the system to the cloud environment.

Conclusion

Docker is a platform that functions as an open-source container to accommodate various types of applications in one place. The main function of using Docker is to help increase the productivity and work effectiveness of developers in building quality products. The methods used by Docker include Docker Image, Container, Client, Host, Engine Rest API, hub, Daemon, and Registry.

References:

What is Docker?

Docker Tutorial : Pengertian, Fungsi dan Cara Kerjanya

Docker overview

8 Reasons Why Every Developer Should Use Docker — And You Won’t Believe #5!