Containers and Virtual Machines

What is a Virtual Machine?

A virtual machine is similar to a hardware server in that it replicates an environment for running applications on actual hardware. It might be system-level, replicating the full operating system, or process-level, running specific apps in a virtual environment.

VMware vSphere

VMware vSphere is server virtualization software developed by VMware. It's a complete solution for managing complicated applications and enabling container-based development.

How does a virtual machine (VM) work?

Virtual machine architecture includes:

• Underlying system (hardware/infrastructure): This includes the physical machine as well as the operating system. Bare metal hypervisors do not require an underlying operating system.
• Hypervisor: Serves as an intermediary between hardware and infrastructure.
• Multiple virtual machines: Use host resources by communicating with the hypervisor.
• Applications and processes: Work with each guest's operating system.

Advantages of Virtual Machine

• Using numerous operating system environments on the same computer.
• Improved system dependability and crash prevention; even if a virtual machine crashes, the host operating system is unaffected due to isolation.
• Added security layer; malware affecting a virtual machine does not compromise the host operating system's security.

Disadvantages of Virtual Machine

• Running several virtual machines can result in an unsteady output.
• Virtual machines are less efficient and slower than actual machines.
• A virtual computer can become infected with the host machine's flaws.

Well-known VM providers

• VMware vSphere
• Oracle VM VirtualBox
• Xen
• Microsoft Hyper-V
• Linux KVM

Where are Virtual Machines and Containers used?

Containers and virtual machines are deployment technologies that let applications run efficiently on servers or devices throughout the software development lifecycle. They handle dependencies, which are inextricably related to the underlying operating system, and create the application environment that connects application code to actual devices.

Similarities between Virtual Machines and Containers

• Containers and virtual machines allow complete application isolation in multi-environment deployments.
• They abstract the underlying infrastructure, reducing user worries.
• Both bundle software into a single image file for simple deployment.
• Image files allow for quick application setup across environments.
• Software processes are responsible for managing system configurations and scaling deployment.
• Roles and usage vary depending on the deployment scenario and application requirements.

Virtual Machines vs. Containers​

• Virtual machines have their own guest OS, which makes them heavier, whereas Docker containers share the host OS, making them lighter.
• VMs provide high isolation, which improves security, whereas containers share the host kernel, which introduces possible safety risks.
• Containers are lighter and use fewer resources, therefore they perform better than virtual machines.
• Containers are easily portable due to the lack of a separate operating system, however, virtual machines are more difficult to migrate due to their standalone operating system.

How can you integrate containers with virtual machines?

• Containers and virtual machines can be used together, although practical applications are limited.
• A virtual machine runs an operating system while simulating specific hardware.
• Installing a container runtime on the VM's operating system enables it to run containers.
• This arrangement is useful for evaluating system-on-chip deployments before hardware use.
• In most cases, containers or virtual machines are sufficient.
• Choosing among them requires an understanding of resource requirements and trade-offs.

Advantages of Containerization over Virtualization

• Lighter and smaller than virtual machines, with a shared operating system kernel for improved resource management and faster boot-up.
• Separate app-specific libraries improve performance and efficiency.
• In comparison to virtualization, this method provides more control and faster implementation.
• Faster boot-up minimizes downtime and increases agility.
• The modular design maximizes resource utilization and facilitates deployment.

Uses of Containers and Virtual Machines

• Choose virtual machines (VMs) for complete OS capability and executing numerous apps on a server.
• Choose Containers to maximize application complexity and resource efficiency.