Docker is a free, open-source, and containerized environment used to build, deploy and share applications in containers. Docker is widely used in DevOps project management because it allows developers to focus on writing code rather than worrying about systems and dependencies. For this purpose, Docker provides different components to manage and build applications and projects better, such as Docker containers.
This write-up will discuss the role of containers in Docker.
What is the Role of Containers in Docker?
The Docker container is a building block of Docker to introduce Docker’s containerized concept. The Docker containers are referred to as a lightweight or small executable package. These containers encapsulate or pack the application, dependencies, and configuration settings. This feature of containers maximizes the application’s performance and minimizes the usage of memory and security risk.
Advantages of Containers
Here are some advantages of Docker containers in Docker:
- Less Complex: Docker containers differ from virtual machines in that they use system resources directly rather than requiring a separate operating system, RAM, and storage.
- Consistency: Containerized applications are more consistent because they encapsulate their dependencies and settings. So developers do not need to worry about the deployment of a container and the result on another operating system.
- Portability: Applications executing inside the containers are more portable. These applications can easily share and deploy on any other machine and OS. It does not encounter the dependencies error as well.
- Greater Efficiency: Docker containers are lightly weighted, easy to deploy, start, scale, and patch.
- Easy Development: Containers are more secure for building and deploying applications as it provides us with a fully isolated environment.
How to Create and Use Containers in Docker?
Docker containers are created through images. To create a container, it is required to build an image first. The Docker images are the template or framework of the container. For the demonstration, go through the provided steps.
Step 1: Make Dockerfile
First make a simple Dockerfile to containerize the application. For instance, we have created the Dockerfile to run a simple “index.html” file in containers:
COPY index.html /usr/share/nginx/html/index.html
ENTRYPOINT ["nginx", "-g", "daemon off;"]
Step 2: Make Image
Make an image from the Dockerfile by utilizing the given command. The “-t” flag defines the image name or tag:
Step 3: Create Container in Docker
Create a container using the image through the “docker create” command. Here, the “-p” option is utilized to specify the exposing port, and “–name” specifies the container’s name:
Step 4: Start Container
To run the containerized application, start the container by utilizing the “docker start” command:
Navigate to the assigned port of the container and check if the container is executing or not.
We have successfully deployed the index.html program inside the container:
We have demonstrated the role of Docker and how to use it to containerize the application.
The main role of a container is to containerize the application by encapsulating or packing the application, dependencies, and configuration settings. The pros of containers in Docker are containers are more portable, scalable, have easy development and deployment, and are more efficient. This write-up has demonstrated the role of containers in Docker and how to use them to containerize the application.