Brief History of Containers
Containers running on a single machine all share the same operating system kernel so they start instantly and make more efficient use of RAM. Images are constructed from layered filesystems so they can share common files, making disk usage and image downloads much more efficient. Docker containers are based on open standards allowing containers to run on all major Linux distributions and Microsoft operating systems.
Containers include the application and all of its dependencies, but share the kernel with other containers. They run as an isolated process in userspace on the host operating system.
Docker is a natural fit for microservice-based architectures
Due to the fundamental differences in architecture (namely the ESXi hypervisor used by VMs versus the shared kernel space leveraged by containers), Linux containers will not achieve the same level of isolation and security. Furthermore, the toolsets available in the VM ecosystem are battle-tested and Enterprise-grade, enabling scores of benefits (stability, compliance, integrated operations, etc) that are indispensable to operations and infrastructure teams.
While containers are certainly a very popular topic right now, containers themselves are
not new. They have existed for many years. FreeBSD, Solaris Zones, LXC...there are
many incarnations of containerization technology.
You may ask - then why is Docker so popular ? For a few good reasons, but mainly
because Docker created a very easy to use framework for deploying and sharing
containers on standard Linux builds.
There are still many challenges to address in this space, however! Security, isolation
and data persistence are areas that are arguably not ready for the Enterprise just yet.
What are Containers?
Containers are an OS-level virtualization method in which the kernel of an operating system allows for multiple isolated user-space instances, instead of just one. The primary benefits of using containers include limited overhead, increased flexibility and efficient use of storage; the container looks like a regular OS instance from the user's perspective. Changes to the image can be made very quickly and pushed to a repository to share with others for further development and utilization.
What is Docker?
Docker containers wrap up a piece of software in a complete filesystem that contains everything it needs to run: code, runtime, system tools, system libraries – anything you can install on a server. This guarantees that it will always run the same, regardless of the environment it is running in.
Containers running on a single machine all share the same operating system kernel so they start instantly and make more efficient use of RAM. Images are constructed from layered filesystems so they can share common files, making disk usage and image downloads much more efficient. Docker containers are based on open standards allowing containers to run on all major Linux distributions and Microsoft operating systems.
Containers include the application and all of its dependencies, but share the kernel with other containers. They run as an isolated process in userspace on the host operating system.
Docker is a natural fit for microservice-based architectures
Virtual machines and containers: better together
Containers provide great application portability, enabling the consistent provisioning of the application across infrastructures. However, applications and data alone are rarely the major barrier to workload mobility. Instead, operational requirements such as performance and capacity management, security, and various management tool integrations can make redeploying workloads to new environments a significant challenge. So while containers help with portability, they’re again only a piece of a bigger puzzle.
Due to the fundamental differences in architecture (namely the ESXi hypervisor used by VMs versus the shared kernel space leveraged by containers), Linux containers will not achieve the same level of isolation and security. Furthermore, the toolsets available in the VM ecosystem are battle-tested and Enterprise-grade, enabling scores of benefits (stability, compliance, integrated operations, etc) that are indispensable to operations and infrastructure teams.
