Docker is an open platform for developing, shipping, and running applications. Docker enables you to separate your applications from your infrastructure so you can deliver software quickly. With Docker, you can manage your infrastructure in the same ways you manage your applications. By taking advantage of Docker’s methodologies for shipping, testing, and deploying code, you can significantly reduce the delay between writing code and running it in production.

Docker is an open-source software platform that enables developers to create, deploy, and manage applications in a wide variety of computing environments. It provides a container-based virtualization system that allows developers to package their applications into isolated containers, which can then be deployed on any operating system or cloud platform.

Docker is an opensource centralized platform designed to create, deploy and run applications.

Docker uses container on the host OS to run applications. It allows applications to use same Linux kernel as a system on the host computer rather than creating a whole virtual OS.

We can install docker on any OS but docker engine runs natively on Linux distributions.

Docker written in “GO” programming language.

Docker is a tool that performs OS level virtualization also known as Containerization.

Before docker many users face the problem that a particular code is running in the developer’s system but not in the user’s system.

Docker was first release in march 2013. It is developed by Solomon Hykes and Sebastian Pahl.

Docker is a set of Platform-as-a-Service that uses OS level virtualization whereas VMWare uses hardware level of virtualization.

👉 Why Docker?

1. Containerization Technology:Docker leverages containerization, allowing developers to encapsulate applications and their dependencies into lightweight, portable containers. Containers offer a consistent and isolated environment, ensuring that applications run consistently across different environments.

2. Portability and Compatibility: Docker containers can run on any system with Docker installed, regardless of the underlying operating system. This portability simplifies the development process, making it easy to move applications between different stages of the development lifecycle and across diverse deployment environments.

3. Resource Efficiency: Containers share the host OS kernel, making them more resource-efficient compared to traditional virtual machines. This efficiency allows for a higher density of applications on a single host, reducing infrastructure costs and improving overall system performance.

4. Isolation and Security: Docker containers provide process and filesystem isolation, enhancing security by isolating applications from each other and from the host system. This isolation prevents conflicts between applications and helps create a more secure runtime environment.

5. Reproducibility and Versioning: Docker uses Dockerfiles to define the steps needed to build a Docker image. This approach ensures that the development environment is reproducible, making it easy to recreate the same environment for testing, deployment, and scaling. Docker images can also be versioned, facilitating rollbacks and minimizing deployment issues.

6. Microservices Architecture Support: Docker is well-suited for microservices architectures, where applications are composed of small, independently deployable services. Each service can run in its own container, promoting scalability, flexibility, and easier maintenance.

7. DevOps Integration: Docker supports DevOps practices by providing a consistent environment for both developers and operations teams. This streamlines collaboration, reduces deployment inconsistencies, and facilitates the “Build Once, Run Anywhere” paradigm.

8. Docker Hub and Registries: Docker Hub, the default public registry, allows developers to share and distribute Docker images easily. Organizations can also set up private registries to securely store and manage their proprietary images.

9. Community and Ecosystem: Docker has a large and active community that contributes to its development and supports users through forums, documentation, and other resources. The extensive ecosystem of tools and integrations further enhances its usability.

👉 Advantages of Docker:

• No pre allocation of RAM.
• CI efficiency: — docker enables you to build a container image and use that same image across every step of the deployment process.
• Less cost.
• It is light in weight.
• It can run on physical h/w / virtual h/w or on cloud.
• You can reuse this image.
• It took very less time to create container.

👉 Disadvantages of Docker:

• Docker is not a good solution for application that requires rich GUI.
• Difficult to manage large number of containers.
• Docker doesn’t provide cross platform compatibility means if an application is designed to run in a docker container in windows than it can’t run in Linux or vice-versa.
• Docker is suitable when the development O.S and testing O.S are same. If the O.S are different then we should use VM.
• No solution for data recovery and backup.

👉 𝐅𝐞𝐚𝐭𝐮𝐫𝐞 𝐨𝐟 𝐃𝐨𝐜𝐤𝐞𝐫:

Docker comes with a variety of features that make it a powerful and widely adopted containerization platform. Here are some key features of Docker:-

• 𝐎𝐩𝐞𝐧 𝐒𝐨𝐮𝐫𝐜𝐞 𝐚𝐧𝐝 𝐋𝐚𝐫𝐠𝐞 𝐂𝐨𝐦𝐦𝐮𝐧𝐢𝐭𝐲: Docker is an open-source project with a large and active community. This community contributes to the development of Docker, shares best practices, and provides support through forums and documentation.

• 𝐂𝐨𝐧𝐭𝐚𝐢𝐧𝐞𝐫𝐢𝐳𝐚𝐭𝐢𝐨𝐧: Docker allows applications and their dependencies to be packaged together in a single container. Containers are isolated, lightweight, and provide consistency across different environments.

• 𝐏𝐨𝐫𝐭𝐚𝐛𝐢𝐥𝐢𝐭𝐲: Docker containers can run on any system that has Docker installed, regardless of the underlying operating system. This portability makes it easy to move applications between development, testing, and production environments.

• 𝐕𝐞𝐫𝐬𝐢𝐨𝐧𝐢𝐧𝐠 𝐚𝐧𝐝 𝐑𝐨𝐥𝐥𝐛𝐚𝐜𝐤𝐬: Docker images can be versioned, allowing developers to roll back to previous versions if needed. This versioning capability simplifies the process of testing, deploying, and maintaining applications.

• 𝐄𝐟𝐟𝐢𝐜𝐢𝐞𝐧𝐭 𝐑𝐞𝐬𝐨𝐮𝐫𝐜𝐞 𝐔𝐭𝐢𝐥𝐢𝐳𝐚𝐭𝐢𝐨𝐧: Containers share the host OS kernel and, as a result, are more resource-efficient than traditional virtual machines. Multiple containers can run on a single host without the need for a separate OS instance for each.

• 𝐃𝐨𝐜𝐤𝐞𝐫𝐟𝐢𝐥𝐞 𝐚𝐧𝐝 𝐈𝐦𝐚𝐠𝐞 𝐁𝐮𝐢𝐥𝐝𝐢𝐧𝐠: Docker uses Dockerfiles, which are text files with a set of instructions, to define how to build a Docker image. This enables the creation of reproducible builds and simplifies the process of setting up development environments.

• 𝐌𝐢𝐜𝐫𝐨𝐬𝐞𝐫𝐯𝐢𝐜𝐞𝐬 𝐀𝐫𝐜𝐡𝐢𝐭𝐞𝐜𝐭𝐮𝐫𝐞: Docker is well-suited for a microservices architecture, where applications are composed of small, independently deployable services. Each service can run in its own container, facilitating scalability and maintenance.

• 𝐃𝐨𝐜𝐤𝐞𝐫 𝐇𝐮𝐛 𝐚𝐧𝐝 𝐑𝐞𝐠𝐢𝐬𝐭𝐫𝐢𝐞𝐬: Docker Hub is a public registry where developers can share and distribute Docker images. Organizations can also set up private registries to store and manage their proprietary images.

• 𝐍𝐞𝐭𝐰𝐨𝐫𝐤𝐢𝐧𝐠: Docker provides networking capabilities that enable communication between containers. Users can define custom networks and link containers to specific networks, allowing for controlled and secure communication.

• 𝐎𝐫𝐜𝐡𝐞𝐬𝐭𝐫𝐚𝐭𝐢𝐨𝐧 (𝐒𝐰𝐚𝐫𝐦 𝐚𝐧𝐝 𝐊𝐮𝐛𝐞𝐫𝐧𝐞𝐭𝐞𝐬): Docker Swarm and Kubernetes are tools for orchestrating and managing the deployment of containerized applications at scale. They provide features like load balancing, scaling, rolling updates, and service discovery.