HYPERVISOR AND CONTAINER
What are Virtual Machines?
A virtual machine can be described as a "software computer" according to VMware's information. A virtual machine is a computer operating system or other computing environment that operates on top of software (a hypervisor) rather than bare metal computer hardware (a server).
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What is Hypervisor?
A hypervisor is a sort of operating system that allows you to operate many virtual machines with various operating systems on a single physical computer or server. The virtual machines are logically separated from one another, and the hypervisor virtualizes the underlying hardware and provides virtual computational resources (CPU, RAM, Storage, and so on) to the virtual machines.Windows HyperV and VMware's ESXi are two of the most used hypervisors nowadays.In short, hypervisors abstract away the hardware layer so virtual machines can run independent of the underlying hardware resources. This technology has gained huge importance in virtualization and cloud computing.
Courtesy:Google Images
What are containers, exactly?
A container encapsulates an application and all of its dependencies into a single unit that can operate everywhere the container engine is installed. To understand this, we may compare what a container engine performs for containers to what a hypervisor does for virtual machines. Similar to how a hypervisor abstracts away hardware for virtual machines so they can run an operating system, a container engine abstracts away an operating system so containers can execute applications.
Some important concepts-
Docker: One of the most important actors in the container field and the creator of the Docker Engine. However, there are a variety of additional container options, like LXC Linux Containers and CoreOS rocket.
Kubernetes: A popular system for managing containers. Other less popular tools include Docker Swarm and Apache Marathon.
Cluster: A group of containers which have a “master” machine that enables orchestration and one or more worker machines which run pods.
Pods: Pods are one or more containers in a cluster that share resources which are deployed for a specific purpose.
We abstract away the hardware that a server would normally offer and run your operating system on virtual PCs.
We utilize containers to abstract away your virtual machine's (or server's) operating system and run your application (e.g. MySQL, Apache, NGINX, etc.).
Container Advantages:
Containers are small and light: Containers only use the libraries that they require. As a result, they start up much faster than virtual machines. Being more lightweight also implies using less hardware and operating systems.
Containers are easily transportable: A container engine can be used. This means that disputes about the environment being the source of a problem with an app should be minimized.
Containers enable microservices: Microservices are small services that communicate with one another to create larger applications or services.
When Should You Use Containers vs. Virtual Machines?
Virtual machines are frequently appropriate for use cases such as:
1)Maintaining consistency and compatibility in existing environments: Servers are already run as virtual machines, and there may be no compelling reasons to change.
2)Using a server or computer to run several apps: There are instances when we simply require a server or computer to run numerous programmes. Virtual machines, as expected, meet this demand.
3)Containers placed on the same host operating system share the kernel, ensuring perfect logical isolation. As a result, they are not as logically separated as virtual computers in terms of security. If isolation is crucial and we must choose between virtual machines and containers, virtual machines may be the better option.
Use of Containers-
1)Containers can be used for a variety of things, including enabling microservices and DevOps. DevOps and microservices are built on containers. Containers may be useful in an environment that adopts DevOps practices. This is due to their portability and speed.
2)Microservice architectures are being adopted by a large number of online applications. If you're designing web apps, switching to a microservices architecture that leverages containers has a number of advantages.
3)Environments in which speed is critical: Containers boot up considerably faster than virtual machines in general. When a reboot is required, this allows for speedier testing and recovery. If we need something quick and light, a container is the way to go.
Where does Docker come in?
Docker is a Linux container-based open-source project. It creates containers on top of an operating system by utilising Linux Kernel capabilities such as namespaces and control groups.
So why is Docker gaining importance?
1. Ease of use: Docker has made it more easier for everyone, including developers, system administrators, and architects, to use containers to swiftly design and test portable apps. Anyone can package a programme on their laptop, which can then operate unchanged on any public cloud, private cloud, or even bare metal. It can be called as “Build once, Run Anywhere.”
2. Speed: Docker containers are small, light, and quick. Containers use lower resources since they are simply environments operating on the kernel. In comparison to virtual machines, which may take longer to generate and run because they must boot up a full virtual operating system every time, Docker containers may be created and launched in seconds.
3. Docker Hub: Docker users also benefit from Docker Hub's growing ecosystem, which may be thought of as a "app store for Docker images." Many images generated by the community are easily available for usage on Docker Hub. It's really simple to find photographs that fit your requirements, ready to download and use with little to no alteration.
4. Modularity and Scalability: Docker makes it simple to separate the functionality of our application into distinct containers. For example, we could run our Postgres database in one container, your Redis server in another, and our Node.js app in still another. Docker makes it easier to connect these containers or build our application, allowing us to scale and update components separately.
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