Docker notes and using Hadoop on container

Docker is a set of platform as a service products that uses OS-level virtualization to deliver software in packages called containers. Containers are isolated from one another and bundle their own software, libraries and configuration files; they can communicate with each other through well-defined channels. (c. Wikipedia) There are a number of sources to learn Docker, but I shall show some useful notes and how to use HDFS using container on Linux.

Useful Notes __ Scala Collections

The Scala collections library involves many classes and traits.The main trait is Iterable, which is the supertrait of both mutable and immutable variations of sequences (Seqs), sets, and maps. Sequences are ordered collections, such as Arrays and Lists. Sets contain at most one of each object, as determined by the == method. Maps contain a collection of keys mapped to values.
All collections are called as immutable by default, to call mutable type you should use scala.collection.mutable package where it is allowed.