@@ -21,12 +21,12 @@ are VMWare's vmdk, Oracle Virtualbox's vdi, and Amazon EC2's ami. In theory thes
automatically package their application into a "machine" for easy distribution and deployment. In practice, that almost never
happens, for a few reasons:
* *Size*: VMs are very large which makes them impractical to store and transfer.
* *Performance*: running VMs consumes significant CPU and memory, which makes them impractical in many scenarios, for example local development of multi-tier applications, and
large-scale deployment of cpu and memory-intensive applications on large numbers of machines.
* *Portability*: competing VM environments don't play well with each other. Although conversion tools do exist, they are limited and add even more overhead.
* *Hardware-centric*: VMs were designed with machine operators in mind, not software developers. As a result, they offer very limited tooling for what developers need most:
building, testing and running their software. For example, VMs offer no facilities for application versioning, monitoring, configuration, logging or service discovery.
**Size*: VMs are very large which makes them impractical to store and transfer.
**Performance*: running VMs consumes significant CPU and memory, which makes them impractical in many scenarios, for example local development of multi-tier applications, and
large-scale deployment of cpu and memory-intensive applications on large numbers of machines.
**Portability*: competing VM environments don't play well with each other. Although conversion tools do exist, they are limited and add even more overhead.
**Hardware-centric*: VMs were designed with machine operators in mind, not software developers. As a result, they offer very limited tooling for what developers need most:
building, testing and running their software. For example, VMs offer no facilities for application versioning, monitoring, configuration, logging or service discovery.
By contrast, Docker relies on a different sandboxing method known as *containerization*. Unlike traditional virtualization,
containerization takes place at the kernel level. Most modern operating system kernels now support the primitives necessary
