Virtual machines virtualize the hardware and containers virtualize the operating system kernels.
- Do not emulate any hardware and do not need to boot up.
- Do not require operating system installation.
- Take up much less space.
- Can run only one app at a time (by design).
- Can interact with their hosts.
- Uses the hypervisor to emulate real hardware.
- Can take up a lot of space.
- Require you to install/configure operating system.
- Can run multiple apps at the same time.
- Cannot interact with their hosts.
Pros of Docker Containers:
- Portability: The containers can run on any system which has Docker installed which makes it easy to move the application from one environment to another.
- Lightweight: The containers take less resources in comparison to virtual machines, which makes it easier to deploy applications in resource-constrained environments.
- Efficiency: A single host can manage multiple containers while launching and stopping containers significantly quicker than virtual machines.
- Isolation: It is feasible to run many containers on the same host without worrying about application conflicts since containers provide an isolation level that is suitable for many applications.
Cons of Docker Containers:
- Security: Containers are vulnerable to security risks that target the host operating system since they rely on the host operating system for security.
- Persistence: Data must be stored in an external storage solution or a separate volume because containers do not by default persist data.
- Complexity: Especially when it comes to network and storage management, managing a large number of containers may be difficult and complex.
Pros of Virtual Machines:
- Isolation: Virtual machines provide a high level of isolation between the host and guest operating systems, enabling multiple virtual machines to run on the same host without risk of application incompatibilities.
- Compatibility: It is feasible to run legacy apps that may not be compatible with the host operating system because virtual machines can run any operating system.
- Security: Applications and data security are made simpler by the ability of virtual machines to be segregated from the host operating system and other virtual machines.
- Persistence: Virtual machines persist data by default, making it easier to manage data for long-term storage.
Cons of Virtual Machines:
- Resource Utilization: Virtual machines consume more resources compared to containers, making them less efficient for resource-constrained environments.
- Management Overhead: Virtual machines require more management overhead compared to containers, making it necessary to install and configure guest operating systems, virtual network interfaces, and virtual storage devices.
- Performance Overhead: Virtual machines introduce a performance overhead compared to running applications directly on the host operating system, making it necessary to balance performance and isolation requirements.