Sarvesh Kumar Singh sarveshseri

Lets assume that you have a cluster with the name - awesome_cluster.

How to enable a `HDFS View`

On a fresh Ambari cluster, we need to follow following steps to create the HDFS view.

Allow the superuser to impersonate other users.

Well... Ambari tries to impersonate the current logged in user with the superuser, and thus the simplest ( but not the best ) thing is to allow the superuser to imperonate all users. Similarily we also need to tell Ambari the name of the host from which the superuser can connect ( simplest is to allow all hosts ).

On Ambari dashboard go to Services > HDFS > Config > Advanced > Custom Core Site and add following new paramters

Fix corrupt file system

First of all switch to the hdfs user

sudo su hdfs

Check file system health

hdfs -fsck /
# or
hdfs fsck hdfs://hdfsHost:port/

Install Oracle Java 8

Ubuntu

sudo add-apt-repository ppa:webupd8team/java
sudo apt-get update
sudo apt-get install oracle-java8-installer

OSX

Our new project

lets say we want to start a new scala project.

cd ~/Works
mkdir ScalaProject

So... the base directory for our project is ~/Work/ScalaProject.

The sbt convention for sources

Now, sbt will follow convention to try to find the following automatically,

First of all, lets understand few date-time standard definitions.

ISO Time String

The standard that we are talking about is formally named ISO 8601:1988 but is popularly also called ISO 8601

ISO 8601 also has support for

years before 0 AD or after 9999
Week based dates
Ordinal dates

mongodump \ 
--host mongo_host \
--username username \
--password password\
--authenticationDatabase auth_db_name \
--db db_name \
--out dump_path

	import org.joda.time.DateTime

	import scala.annotation.tailrec
	import scala.util.Random

	object RANStream {
	val randomAlphaNumIterator = Random.alphanumeric.iterator

	@tailrec
	def getRandomString(length: Int, acc: String = ""): String = {

	import scala.collection.mutable.Stack

	case class Tower(name: String, disks: Stack[Int])

	case class TohState(src: String, tgt: String, tmp: String)
	case class TohStep(move: String, before: TohState, after: TohState)

	object LazyToh {

	val srcName = "SRC"

	object Main {

	def main(args: Array[String]): Unit = {
	println("---------")
	println("Hi,")
	println("I am Sbt and I am simple. :D")
	println("---------")
	}

	}

	realm=my maven repo
	host=my-maven-repo-host.com
	user=xxxx
	password=yyyy