Containerization is the technology that allows you to package an application and its dependencies together in a container, which can then be run on any machine that has a container runtime installed. This allows you to deploy and run applications in a predictable and consistent manner, regardless of the underlying infrastructure.
Containers are isolated from each other and the host operating system, which makes them lightweight and portable. This makes them an attractive alternative to traditional virtualization, which requires a full operating system installed on each virtual machine.
Containers are often used in conjunction with microservices, which are small, modular units of code that can be developed, tested and deployed independently of each other. This allows for faster development cycles and easier maintenance and updates of complex applications. Containers are also the usual way to implement serverless computing. In this model, you package your application and its dependencies into a container, and the cloud provider runs the container on demand. This allows you to take advantage of the benefits of containerization, such as portability and isolation, while also taking advantage of the pay-per-use model of serverless computing in public clouds. Open-source solutions are also available for serverless architectures.
Containers vs Virtual Machines (VMs)
Containers and VMs are both technologies that allow you to run applications in an isolated environment. However, there are some key differences between the two:
- Isolation: Both containers and VMs provide isolation, but they do it in different ways. VMs use hardware virtualization to create a separate environment for each application, which includes its own operating system, system libraries, and application code. Containers, on the other hand, share the host operating system and use namespaces and cgroups to provide isolation. This means that containers are generally lighter weight and use fewer resources than VMs.
- Portability: Containers are generally more portable than VMs because they do not include a full operating system and are therefore more lightweight. This makes it easier to move containers between environments, such as from a developer’s laptop to a staging environment to production. VMs, on the other hand, are more complex and include a full operating system, which makes them less portable.
- Performance: VMs can offer better performance than containers because they have their own dedicated operating system and hardware resources. However, containers can still provide good performance in many cases, especially if the host system has sufficient resources.
- Scalability: Containers are generally easier to scale than VMs because they are lightweight and do not require a full operating system. This makes it easier to add or remove containers as needed to meet changing demands.
To summarize, containers and VMs are both technologies that allow you to run applications in an isolated environment, but they differ in terms of isolation, portability, performance, and scalability. The right choice for your needs will depend on your specific requirements and use case.
Key takeaways for Containers
- Portability. Containers are portable, meaning that they can be easily moved from one environment to another. This makes it easier to deploy applications on different platforms, such as from a developer’s laptop to a staging environment to production.
- Isolation. Containers are isolated from each other and the host operating system, which means that they do not interfere with each other or with the host system. This makes it easier to run multiple applications on a single machine without worrying about conflicts.
- Resource efficiency. Containers are lightweight and use fewer resources than traditional virtualization. This makes it possible to run more applications on a single machine, which can be useful in environments where resources are limited.
- Ease of deployment. Containerization tools like Docker make it easy to build, manage, and deploy containers, which can be useful in environments where there are frequent updates or new applications are being added frequently.
- Security. Containers are isolated, but they are not entirely secure. It is important to carefully manage access to containers and to ensure that they are properly patched and updated to prevent security vulnerabilities.
- Complexity. Containerization can add complexity to an application, especially if you are using multiple containers or orchestrating them with a tool like Kubernetes. It can take time to learn how to use these tools effectively.
- Performance. While containers are generally lightweight and efficient, they may not provide the same level of performance as a dedicated physical machine. This can be a concern in environments where high performance is critical.
Several tools and technologies are available to help you get started with containerization. The most popular container engine is Docker, an open-source tool for building, deploying, and managing containers via a simple command-line interface, making it easy to use and widely adopted by developers. Rkt, Containerd, and LXC are alternatives to Docker. Other open-source tools, more focused on the orchestration of containers, include Kubernetes, OpenShift, and Nomad. Containerization platforms are also available in the public cloud, like Amazon Elastic Container Service (ECS) or Google Kubernetes Engine (GKE) to manage your containers when deployed in the cloud.