Containers are packages of software that contain all of the necessary elements to run in any environment. In this way, containers virtualize the operating system and run anywhere, from a private data center to the public cloud or even on a developer’s personal laptop. From Gmail to YouTube to Search, everything at Google runs in containers. Containerization allows our development teams to move fast, deploy software efficiently, and operate at an unprecedented scale.
Containers defined as:
Containers are lightweight packages of your application code together with dependencies such as specific versions of programming language runtimes and libraries required to run your software services.
Containers make it easy to share CPU, memory, storage, and network resources at the operating systems level and offer a logical packaging mechanism in which applications can be abstracted from the environment in which they actually run.
Why Do We Need Containers?
The main advantage of containers is that they are lightweight and portable and thus helps the developer a lot in configuring and deploying their application. There are many reasons for using Containers but only some of them are listed below:
Lightweight: Containers share the machine OS kernel and therefore they don’t need a full OS instance per application. This makes the container files smaller and This is the reason why Containers are smaller in size, especially compared to virtual machines. As they are lightweight, thus they can spin up quickly and can be easily scaled horizontally.
Portable: Containers are a package having all their dependencies with them, this means that we have to write the software once and the same software can be run across different laptops, cloud, and on-premises computing environments without the need of configuring the whole software again.
Supports CI/CD: Due to a combination of their deployment portability/consistency across platforms and their small size, containers are an ideal fit for modern development and application patterns—such as DevOps, serverless, and microservices.
Improves utilization: Containers enable developers and operators to improve CPU and memory utilization of physical machines.
Different Types of Containers
The very growth and expansion in container technology bring a large set of choices to choose from. Docker is the best known and most widely used container platform by far. But there are some more technologies on the container landscape, each with their own individual use cases and advantages.
Docker
Docker is one of the most popular and widely used container platforms. It enables the creation and use of Linux containers. Docker is a tool which makes the creation, deployment and running of applications easier by using containers. Not only the Linux powers like Red Hat and Canonical have embraced Docker, but the companies like Microsoft, Amazon, and Oracle have also done it. Today, almost all IT and cloud companies have adopted Docker.
LXC LXC is an open-source project of LinuxContainers.org. The aim of LXC is to provide isolated application environments that closely resemble virtual machines (VMs) but without the overhead of running their own kernel. LXC follows the Unix process model, in which there is no central daemon. So, instead of being managed by one central program, each container behaves as if it’s managed by a separate program. LXC works in a number of different ways from Docker. For example, we can run more than one process in an LXC container, whereas Docker is designed in such a way that running a single process in each container is better.
CRI-O
CRI-O is an open-source tool which is an implementation of the Kubernetes CRI (Container Runtime Interface) to enable using OCI (Open Container Initiative) compatible runtimes. Its goal is to replace Docker as the Container engine for Kubernetes. It allows Kubernetes to use any OCI-compliant runtime as the container runtime for running pods. Today, it supports runc and Kata Containers as the container runtimes but any OCI-conformant runtime can be used.
What are the benefits of containers?
Separation of responsibility
Containerization provides a clear separation of responsibility, as developers focus on application logic and dependencies, while IT operations teams can focus on deployment and management instead of application details such as specific software versions and configurations.
Workload portability
Containers can run virtually anywhere, greatly easing development and deployment: on Linux, Windows, and Mac operating systems; on virtual machines or on physical servers; on a developer’s machine or in data centers on-premises; and of course, in the public cloud.
Application isolation
Containers virtualize CPU, memory, storage, and network resources at the operating system level, providing developers with a view of the OS logically isolated from other applications.
What are containers used for?
Containers offer a logical packaging mechanism in which applications can be abstracted from the environment in which they actually run. This decoupling allows container-based applications to be deployed easily and consistently, regardless of whether the target environment is a private data center, the public cloud, or even a developer’s personal laptop.
Agile development
Containers allow your developers to move much more quickly by avoiding concerns about dependencies and environments.
Efficient operations
Containers are lightweight and allow you to use just the computing resources you need. This lets you run your applications efficiently.
Run anywhere
Containers are able to run virtually anywhere. Wherever you want to run your software, you can use containers.