What are Containers in Docker?

What are Containers?

Docker containers offer a practical solution to the challenge of running an application across multiple environments. By packaging everything an application needs to run into a container, we can make deployment and management much easier. This is especially beneficial when it comes to ensuring consistency between different environments, as all of the application's components and internal dependencies are sorted out before running.

What are the Benefits of Containers?

Solving the challenge of running applications reliably across multiple environments is essential for development teams that want to move quickly, deploy software efficiently, and operate at an unprecedented scale. Containerisation helps achieve it.

Containers is a container runtime that helps manage the life of a container on any physical or virtual machine. It's used by the docker engine to create, start, stop, and destroy containers. Containers can also pull container images from registries, mount storage, and enable networking for a container.

Let's take a look at some of the other benefits of docker containers.

Separation of Responsibility

Containerization is a great way to manage applications because it enables greater separation of responsibility. Splitting a complex application into less complex entities can help to make the application more manageable. This way, each part of the application is a less complex entity, and changes can be made to parts without having to rebuild the entire application.

Workload Portability

Running applications on different operating systems can be a hassle, but docker containers can make it much easier. Docker containers package the software and dependencies together, so they can run anywhere - on Linux, Windows, Mac, the public cloud, or a local machine. This flexibility greatly helps during development and deployment.

Application Isolation

Docker containers virtualize CPU, memory, storage, and network resources at the operating system level. From a security perspective, application isolation helps prevent some attacks. Isolation also provides developers with a view of the OS logically isolated from other applications.

Less Overhead

Docker containers are much lighter in weight than virtual machines, making them much easier to move and scale. With a virtual machine, you're dealing with an entire operating system that can take up several gigabytes. In contrast, a container may only be tens of megabytes in size. This difference in size makes a big difference when it comes to moving and scaling applications.

More Consistent Operation

Docker containers provide Execution consistency by packaging code and processes to fit release and management processes. This way, teams can not only improve release quality but also increase consistency.

Greater Efficiency

Docker containers can be started and deleted as needed, quickly freeing up resources on their hosts. Virtual machines can't do this. A virtual machine takes several minutes to boot up its operating system and begin running the applications it hosts. In this way, docker containers provide a more efficient solution.

Better Application Development

Containerization is a boon for application development as it allows apps to be "written once and run anywhere." This not only helps with vendor compatibility but also offers other benefits like fault isolation, ease of management, and security. In other words, containerization makes it easier to develop and deploy applications.

Containers vs VMs

Let's take a look into each of their Pros & Cons.

Containers

• Containers only virtualize software layers above the operating system level.
• They provide a faster iteration speed due to their lightweight nature.
• With containers, you can quickly and easily test out new ideas without having to worry about setting up a lot of infrastructures.

Virtual Machines

• Virtual machines virtualize an entire machine down to the hardware layers.
• They offer full isolation security, which means that they are unaffected by any outside exploits or interference.
• They are more dynamic and can be developed interactively. The software can be installed manually on the virtual machine, and the virtual machine can be snapshotted to capture the current configuration state.

Virtual machines should be preferred if you have specific hardware requirements for your project. For other use cases, docker containers should be preferred.

What are Containers used for?

Agile Development

Containerization is a method of packaging software that allows developers to create applications that are based on the agile methodology principles of sustainable resource consumption, efficient software delivery, continuous integration, continuous delivery, continuous deployment, and collaboration with end-users.

Therefore, docker containers are used for application development as they can help make software development, testing, delivery, and deployment more agile.

Efficient Operations

Docker containers help to make things more efficient by packing up an entire runtime environment, which includes the application plus all dependencies, libraries, binaries, and configuration files. This makes applications portable, so they can run anywhere. Docker containers are also easy to set up and take down, so they're very flexible.

Run Anywhere

Docker containers offer portability, i.e. the ability to run anywhere. The ability to move applications from a developer's laptop to an organization's internal data center and out to different cloud providers with little trouble.

Apart from this, they start faster and are easier to move around than virtual machines. Right?

Container Use Cases

Docker containers can be used to run any application and database. As long as the application or database does not have any hardware dependencies - it can be containerized and run as docker containers.

How do Docker and Kubernetes relate to Containers?

Docker is a containerization platform and runtime. Kubernetes is a platform for running and managing containers from many container runtimes.

Additional Resources:

1. Interview Questions on Kubernetes