Docker Crash Course for DevOps Engineers

 

Introduction to Docker:

            Containerization is a lightweight method of running applications in isolated environments using shared OS kernels, while virtualization uses full virtual machines with separate operating systems to achieve isolation.

Containerization:

    Running applications in isolated user spaces (containers) on the same operating system kernel.

• Technology: Docker, Podman, containerd
• Isolation Level: Process-level isolation using namespaces and cgroups
• Resource Usage: Lightweight — shares OS kernel, faster startup, lower overhead
• Portability: Highly portable across environments (dev, test, prod)
• Use Case: Microservices, CI/CD pipelines, cloud-native apps.

Virtualization:

    Running multiple operating systems on a single physical machine using a hypervisor.

• Technology: VMware, VirtualBox, KVM, Hyper-V
• Isolation Level: Full OS-level isolation — each VM has its own OS and kernel
• Resource Usage: Heavy — requires more CPU, RAM, and disk space
• Portability: Less portable due to OS dependencies
• Use Case: Legacy applications, multi-OS testing, infrastructure-level isolation