This guide provides an overview of various methods to access and collect metrics from Hadoop components such as HDFS, MapReduce, YARN, and ZooKeeper. It covers collecting metrics via APIs and JMX for NameNodes and DataNodes, obtaining MapReduce counters, using Apache Ambari and Cloudera Manager for monitoring purposes, and gathering ZooKeeper metrics through Jmxterm or the four-letter words method. Additionally, it highlights Datadog's integrations with Hadoop components for comprehensive monitoring solutions.