Containers brief intro

Containers are a solution to the problem of how to get software to run reliably when moved from one computing environment to another.

This could be from a developer's laptop to a test environment, from a staging environment into production and perhaps from a physical machine in a data center to a virtual machine in a private or public cloud.

Problems arise when the supportiing software environment is not identical.

Example: You're going to test using Python 2.7, and then it's going to run on Python 3 in production and something weird will happen. Or you'll rely on the behavior of a certaing version of an SSL llibrary and another one will be installed.

The network topology might be different, or the security polices and storage might be different but the software has to run on it.

A container consists of an entire runtime environment: an application, plus all its dependencies, libraries and other binaries, and configuration files needed to run it, bundled into one package.

By containerizing the application platform and its dependecies, differeces in OS distributions and underlying infrastructure are abstracted away.