There are a lot of companies which still use legacy technologies and whenever a new person joins the company he has to set up everything in his system so that he can contribute. I am not only talking about the codebase, it’s all about the softwares, environments needed to run the codebase. If the steps for configuring is not documented well (after all we are humans) then it might take days for him to get started. This is where Docker can help the companies which are using newer or older technologies so that they create a package of any application to be used in any system.
In simple terms, Docker is a tool designed which makes it quite easy to create, deploy, and run applications by using containers. Containers allow a developer to package up an application with all of the parts it needs, such as libraries and other dependencies, and ship it all out as one package.
By using containers, developers can be sure that their applications will work on any other machine, regardless of any customized settings that machine might have installed. This makes it easier to develop and test applications. And every team memebers can have the same containers and thus they all will be on the same page.
If we envision a container, it contains things like
- source code
- project dependencies (maven or nuget packages)
- environment files
- database setup
- runtime environment
So it contains almost everything using which you can use to run your project without worrying about anything. So to create any container or manage it we need Docker.
To get started with Docker, you’ll need to install the Docker Engine on your machine. You can then start creating and running Docker containers.
To create a Docker container, you’ll need to write a
Dockerfile, which is a text file that contains instructions for building the image. The image is the executable package that contains your application and all of its dependencies.
A simple docker file creating a redis-server.
FROM redis COPY redis.conf /usr/local/etc/redis/redis.conf CMD [ "redis-server", "/usr/local/etc/redis/redis.conf" ]
Once you have an image, you can use the
docker run command to create and start a container from the image. You can also use the
docker stop, and
docker rm commands to manage the lifecycle of your containers.
Why Use Docker
Isolation: Each container runs in its own environment and is isolated from other containers. This means that containers do not interfere with each other, and you can run multiple containers on the same host (like a windows or linux virtual machine) without any conflicts.
Ease of use: Docker makes it easy to package and deploy applications. You can use pre-built images from Docker Hub, a registry of Docker images, or create your own images. This is where a new developer can start his work as quickly as possible.
Efficiency: Because containers share the host operating system and its kernel, they are lightweight and start up quickly. This makes it easy to scale applications horizontally across a fleet of hosts.
Portability: Docker containers can run on any machine that has the Docker Engine installed, regardless of the operating system or infrastructure. This makes it easy to move containers between environments, such as from development to production.
Version control: Docker makes it easy to version and roll back changes to your applications. You can use tags to mark specific versions of an image and use them to deploy your applications.
Start Using Docker For Legacy Applications
Docker can be a useful tool for modernizing legacy applications. By packaging a legacy application in a Docker container, you can take advantage of the benefits of containerization, such as isolation, portability, and ease of deployment.
Here are a few ways that Docker can be used to modernize legacy applications:
Ease of deployment: One of the main benefits of Docker is that it makes it easy to deploy applications. With a legacy application, you might have to worry about installing and configuring various dependencies and libraries on each host. With Docker, you can package the application and its dependencies in a single container, and then deploy the container to any host that has the Docker Engine installed.
Testing and continuous integration: Docker can be used to set up a continuous integration (CI) pipeline for a legacy application. You can use Docker to build and test the application in a consistent environment, and then deploy the container to production. This can help to reduce the risk of issues arising when deploying the application to different environments.
Scaling and resource management: Docker allows you to run multiple containers on a single host, which can be useful for legacy applications that might not be designed to scale horizontally. You can also use Docker to manage resource allocation for your legacy applications, so that they do not consume too many resources on the host.
Overall, Docker can be a useful tool for modernizing legacy applications by making them easier to deploy, test, and scale. It can also help to isolate the legacy application from the rest of the system, reducing the risk of conflicts or issues arising.