How To Create And Deploy Docker Applications
A brief overview of Docker
What is Docker? Docker is a tool that enables developers to create, deploy, and run applications in containers. Simply put, Docker removes the endless environmental configuration conflicts that can occur during collaboration. Docker can be used to run and maintain applications, side by side, in isolated containers. Development teams can use it to complement existing agile and DevOps delivery practices. As a platform, Docker can run securely on Linux and Windows environments.
Docker saves developers time and automates repetitive tasks often associated with provisioning new development environments, which allow developers to focus on writing code.
Docker makes it easy to run applications in any environment that has Docker running. There are three main Docker variants:
- Docker Enterprise Edition (Docker EE)
- Docker Community Edition (Docker CE)
- Docker Cloud
The choice of a variant depends on the type of environment you are setting up.
Creating a Docker image
Docker Containers are created from Docker images. To get your application distributed to different machines, you must create a Docker image to send to each. You can do this using a Dockerfile. To build the image, you will use the build command. Proceed to host your docker image on a registry, then pull and run the image on the target machine.
Below is an example of a simple Dockerfile from the Docker documentation:
FROM docker/whalesay:latestRUN apt-get -y update && apt-get install -y fortunesCMD /usr/games/fortune -a | cowsay
Setting up the Environment
To easily distribute your applications, you will need somewhere to share them. You will thus need to get your Docker environment ready to run your application. You do this by using the command line and a few tools.
These virtual machines are responsible for setting up the Containers we have discussed. Setting up your local machine will be different from creating Dockerized cloud servers.
Deploying on a server
Now that you have your Docker machines running, the Docker Hub repository set up, and the Docker image built, you can now deploy the application across your machines.
First, push your application to the repository. Next, pull your application from your repository to the other machines. You can do this with the docker run command. The command will automatically find, pull, and run your new application.
Automating the Docker deployment process
So that you don‘t have to run all of those commands every time you make a change to an application, luckily, there are many tools to use to streamline your workflow and automate the whole Docker application deployment process.
You can follow this docker tutorial to see the complete automation process:
Kubernetes Vs. Docker
A container holds all of an application’s code, dependencies, libraries, and other necessary configurations. The container can then be run as its process on top of a machine using a tool such as Docker.
Containers are good at packaging an application with its dependencies so that you can run it anywhere easily. However, they have some limitations. When building a scalable application using containers, you need some way to manage the containers in the most efficient way possible. That‘s where container orchestration tools come into play.
Google Kubernetes and Docker Swarm are powerful tools to run your application in a distributed, highly resilient environment while appearing as one application to anyone using it.
Docker Swarm is the native clustering and container management tool for Docker. Kubernetes, on the other hand, is Google‘s take on container orchestration. It‘s open-source and works with Docker containers. It‘s one of the most feature-rich and powerful frameworks.
Docker is a game-changer and has greatly altered the application development world. Containerization is the use of Linux containers to deploy applications. Docker is one tool that lets developers create, deploy, and run applications in containers.
As we have seen, Docker lets you get many more individual applications running on the same number of servers as other technologies. It makes developing encapsulated, ready-to-run applications a breeze — delivering everything in ’containers‘ that hold all libraries and dependencies for an app. It makes managing your applications and deploying them to live servers much easier. You can edit an application, push the new docker image to a repository, then instantly run that application anywhere. We have also briefly discussed Kubernetes vs Docker.