Ansible for Bigtop

This repo is a collection of Ansible roles and playbooks for the deployment of a Hadoop cluster using packages built by Apache Bigtop. These scripts are eventually intended to be submitted to that project, as currently there are only recipes for Puppet.

Usage

Assuming that this repo has been cloned to /etc/ansible on a machine that can reach your cluster:

$ ansible-playbook hadoop-playbook.yml

This command should be suitable to install and configure the following Hadoop components:

• Zookeeper
• HDFS
• YARN
• Hive

Also included in the utils directory are playbooks to ease administration tasks (i.e. starting, stopping, and restarting services). In particular, the start-hadoop.yml playbook can fully bootstrap a cluster by formatting HDFS and starting all necessary services.

$ ansible-playbook utils/start-hadoop.yml

You can start specific services using Ansible tags:

$ ansible-playbook --tags 'zookeeper,hdfs' utils/start-hadoop.yml

You can also start, stop, or restart specific subcomponents of each service (e.g. just HDFS NameNodes, or just the Hive Metastore):

$ ansible-playbook --tags 'namenodes' utils/restart-hadoop.yml

OR

$ ansible-playbook --tags 'namenodes' utils/services/hdfs/restart-hdfs.yml

$ ansible-playbook --tags 'hive-metastore' utils/restart-hadoop.yml

OR

$ ansible-playbook --tags 'hive-metastore' utils/services/hive/restart-hive.yml

Requirements

OS: CentOS 7 (fully tested on 7.4, 7.5, and 7.6)
Hadoop: 2.x
Java > 1.6 (but < 1.9)

Starting at the top, the following variables must properly defined in group_vars/all/all:

• cluster_name: name of your cluster (this will be your default HDFS namespace)
• dns_domain: domain name of your cluster

Also of note is that these playbooks have only been tested using Java 1.8 (OpenJDK). To use Oracle Java, change the names of these packages in the java_pkgs variable.

Limitations

Currently, only RedHat-based distributions are supported. There are plans to support Debian-based distributions in the future. Fair warning, however: that particular task is not necessarily high priority. Other limitations:

• can only build a cluster that uses HDFS HA
• can only build a cluster that uses non-HA YARN

...amongst others

TODO

Add roles for:

• ResourceManagers
• NodeManagers
• Hadoop Clients
• Hive Metastore
• Hive Server
• Hive Clients

Once these are done, move on to other services

Also, add support for:

• non-HA HDFS
• HA YARN
• Debian-bases OSes

Need documentation for all roles!