Osm_ElasticSearch_Cluster

This repo controls the Ansible Role for ElasticSearch cluster installation.

Key Features

Standalone setup Cluster setup TLS encryption

Supported os

Redhat 7 Ubuntu 14/16/18 Amazon Linux

Dependencies

python
Java 1.8 or greater

Role Variables

We have categorized variables into two part i.e. Manadatory and Optional

Mandatory Variables

Variable	Default Value	Possible Values	Description
elasticsearch_version	7.16.2	Any es version as required	Exact es version which we need to install
elasticsearch_series	7	6/7/8 etc	Es major version
cluster_name	es-cluster	Cluster name	Cluster name
http_port	9200	Any Linux port	Assign a port to connect with es
tcp_port	9300	Any Linux port	Port through es node will communicate between them
tls_enable	no	Yes or no	This variable will enable or disable tls encryption
key_name	node1.key	Key name	Key name if tls encryption is enabled
certificate_name	node1.crt	Certificate name	Certificate name if tls encryption is enabled
certificate_authorities_name	ca.crt	Certificate authorities name	Certificate authorities name if tls encryption is enabled
nofile_limit	65536	65536	This limits the number of file descriptors any process owned by the specified domain can have open at any one time
nproc_limit	5000	5000	Nproc is defined at OS level to limit the number of processes per user
swapness	1	0 to 100	Swappiness is the kernel parameter that defines how much (and how often) your Linux kernel will copy RAM contents to swap. This parameter's default value is “60” and it can take anything from “0” to “100”. The higher the value of the swappiness parameter, the more aggressively your kernel will swap.
vm_max_count	2621444	2621444	Elasticsearch uses a mmapfs directory by default to store its indices. The default operating system limits on mmap counts is likely to be too low, which may result in out of memory exceptions.
m_lock	false	False or true	When the JVM does a major garbage collection it touches every page of the heap. If any of those pages are swapped out to disk they will have to be swapped back in to memory. That causes lots of disk thrashing that Elasticsearch would much rather use to service requests. There are several ways to configure a system to disallow swapping. One way is by requesting the JVM to lock the heap in memory through mlockall (Unix) or virtual lock (Windows). This is done via the Elasticsearch setting bootstrap.memory_lock
standalone	no	Yes or no	This variable is to mention standalone setup

Optional Variables

Variable	Default Value	Possible Values	Description
es_url	"elasticsearch/elasticsearch-{{ elasticsearch_version }}"	Url for es	Url for es
es_service	elasticsearch.service	Service file name	Service file name
es	elasticsearch	elasticsearch	Es name
es_jvm_dump	/var/lib/elasticsearch/heap	Any path	Path to jvm dump
log_path	/var/log/elasticsearch	Any path	Es log path
data_path	/var/lib/elasticsearch	Any path	Path to es data
systemd_path	/usr/lib/systemd/system	/usr/lib/systemd/system	service file path
conf	/etc/elasticsearch/	/etc/elasticsearch/	es config file path

Node defination:

Define your type of nodes in host/inventory file based on the below format. Can increase the node counts as much you want.

[es]
es1 ansible_host=127.0.0.1 ansible_ssh_user=root
es2 ansible_host=127.0.0.2 ansible_ssh_user=root
es3 ansible_host=127.0.0.3 ansible_ssh_user=root
[esm]
esm1 ansible_host=127.0.0.1 ansible_ssh_user=root
esm2 ansible_host=127.0.0.2 ansible_ssh_user=root
[esd]
esd1 ansible_host=127.0.0.1 ansible_ssh_user=root
esd2 ansible_host=127.0.0.2 ansible_ssh_user=root
[esc]
esc1 ansible_host=127.0.0.3 ansible_ssh_user=root

Where,
es: all es servers esm: is master node information
esd: is data node information
esc: is client node information

add all es servers IP under group es. The add the specific server ip whom u want to be a master node in the group [esm], special mention this server need to be present in [es] group.do the same for data node and client node.

Remember that one same server can be used for data and master node but for clients we need a specific server.

Example Playbook

---
- hosts: all
  become: true
  roles:
    - osm_elasticsearch_cluster

Usage

There are multiple ways of executing the playbook according to your environment

To run the complete role

ansible-playbook -i hosts site.yml

To run with TLS encryption and vault

ansible-playbook -i host --ask-vault-pass site.yml

TLS encryption enable

To enable tls encryption first got to the vars/main.yml file and change tls_enable variable value to “yes” then keep all certs in files directory and enter their name in vars/main.yml file. After that encrypt the certs with the vault. Run the bellow command and encrypt the certs and set a password.

ansible-vault encrypt ca.crt

Then run the role with the bellow command and u have provide the password that u have used to encrypt the certs.

ansible-playbook -i host --ask-vault-pass site.yml

you can use this password to encrypt and decrypt the certs

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Author

Moulendu Ghosh