Installing Elasticsearch using Ansible – The Quick Way!

Posted in: Open Source, Site Reliability Engineering, Technical Track

This is the first of a series of blog posts related to Elastic Stack and the components around it. This first one covers how to install Elasticsearch using Ansible. The final objective is to deploy and secure a production-ready environment using these freely available tools. 

Elasticsearch is, without any doubt, a very powerful tool that allows us to store a great quantity of data in order to search very efficiently, but it does way more! Very often, due to the complexity of the stack, we struggle to give it a try in order to install it. Even though the official installation documentation is available, it generally doesn’t include the use of a repeatable, quick and efficient process to do so. In order to overcome this issue, I propose to deploy the Elastic Stack using the vendor-provided Ansible tools.

Architecture

For this stack, we’ll consider a basic architecture:

Elasticsearch cluster architecture proposal

Deploying with Ansible

In order to deploy the Elastic Stack using Ansible, there is one official repository with the required Ansible playbook to do the work really fast and easily. Even though the README file is explicit and complete, very often we can get lost in the sea of different options and recommendations. If you want to just deploy a cluster with the following architecture, production-ready* follow this guide!

*Of course, “production-ready” can mean so many different things depending on the person and the situation, can’t it? ;)

Production Ready

“Production Ready” on MonkeyUser.Com. Permission to use the image at https://www.monkeyuser.com/about/index.html

 

To begin with, it’s just a matter of installing a couple of components following these prerequisites:

  • Have Ansible installed and working on a VM or instance that can reach all of your Elastic Stack cluster network components. (Ansible resources are here).
  • Have access to your created VMs for the Elastic cluster you wish to install. (It is out of the scope of this blog post to go through sizing and other advanced considerations, although that is very good material for a further post in the future!)

We need to note that by using Ansible, it doesn’t matter what OS your VMs have. You can have Red Hat Enterprise Linux, CentOS, Ubuntu or any other servers. It really doesn’t matter!

Once you have the above requisites ready and Ansible configured and up and running, it’s just a matter of getting the repository accessible with the following command:

ansible-galaxy install elastic.elasticsearch,7.4.2

YAML config files

Then, you need to create a YAML inventory for your Elasticsearch nodes. (Please remember YAML is very picky when it comes to blank spaces!).

For this example, we’ll deploy three data, three masters and two coordinating nodes. We’ll call this file inventory.yml.

[hosts]
  esdata1
  esdata2
  esdata3
  escoord1
  escoord2
  esmaster1
  esmaster2
  esmaster3
[data]
  esdata1
  esdata2
  esdata3
[masters]
  esmaster1
  esmaster2
  esmaster3
[coordinating]
  escoord1
  escoord2

Then, we’ll create the elastic.yml file in order to have our cluster deployed. We’ll continue with the example above:

(Note: adjust the heap size on the three sections of the file to your RAM requirements!)

- hosts: masters
  roles:
    - role: elastic.elasticsearch
  vars:
    es_heap_size: "8g"
    es_config:
      cluster.name: "esprd"
      network.host: 0
      cluster.initial_master_nodes: "esmaster1,esmaster2,esmaster3"
      discovery.seed_hosts: "esmaster1:9300,esmaster2:9300,esmaster3:9300"
      http.port: 9200
      node.data: false
      node.master: true
      node.ingest: false
      node.ml: false
      cluster.remote.connect: false
      bootstrap.memory_lock: true
- hosts: data
  roles:
    - role: elastic.elasticsearch
  vars:
    es_data_dirs:
      - "/var/lib/elasticsearch"
    es_heap_size: "30g"
    es_config:
      cluster.name: "esprd"
      network.host: 0
      discovery.seed_hosts: "esmaster1:9300,esmaster2:9300,esmaster3:9300"
      http.port: 9200
      node.data: true
      node.master: false
      node.ml: false
      bootstrap.memory_lock: true
      indices.recovery.max_bytes_per_sec: 100mb
- hosts: coordinating
  roles:
    - role: elastic.elasticsearch
  vars:
    es_heap_size: "16g"
    es_config:
      cluster.name: "esprd"
      network.host: 0
      discovery.seed_hosts: "esmaster1:9300,esmaster2:9300,esmaster3:9300"
      http.port: 9200
      node.data: false
      node.master: false
      node.ingest: false
      node.ml: false
      cluster.remote.connect: false
      bootstrap.memory_lock: true

Execute!

Once we have our YAML definition, now it’s just a matter of executing the following command. Do it and watch the magic flow! :

ansible-playbook elastic.yml -i inventory.yml

Review

After a few minutes, the above command should get us a nice Elasticsearch cluster up and running. We can verify its status like this:

$ curl -XGET 'https://esmaster1'
{
  "name" : "esmaster1",
  "cluster_name" : "esprd",
  "cluster_uuid" : "ABC6pGHgRWGhooEjvIElkA",
  "version" : {
    "number" : "7.4.2",
    "build_flavor" : "default",
    "build_type" : "rpm",
    "build_hash" : "7a013de",
    "build_date" : "2019-12-07T14:04:00.380842Z",
    "build_snapshot" : false,
    "lucene_version" : "8.0.0",
    "minimum_wire_compatibility_version" : "6.8.0",
    "minimum_index_compatibility_version" : "6.0.0-beta1"
  },
  "tagline" : "You Know, for Search"
}

Furthermore, we can confirm cluster health as well:

$ curl -XGET 'https://esmaster1:9200/_cluster/health?pretty'
{
  "cluster_name" : "esprd",
  "status" : "green",
  "timed_out" : false,
  "number_of_nodes" : 8,
  "number_of_data_nodes" : 3,
  "active_primary_shards" : 0,
  "active_shards" : 0,
  "relocating_shards" : 0,
  "initializing_shards" : 0,
  "unassigned_shards" : 0,
  "delayed_unassigned_shards" : 0,
  "number_of_pending_tasks" : 0,
  "number_of_in_flight_fetch" : 0,
  "task_max_waiting_in_queue_millis" : 0,
  "active_shards_percent_as_number" : 100.0
}

Final words

Sadly, one thing I find disturbing in this time and age is Elastic Stack’s default behavior. It’s always configured to have all of the messages exchanged between the components in the stack in plain text!

For now, that’s it, this is how we install Elasticsearch using Ansible. The next post explores the topic of securing your installation.

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About the Author

Site Reliability Consultant
Mexican living in France with way too many interests to list here, but in general technology is my passion. I love running, videogames (Final Fantasy series!), Pokémon Go, languages and food! SysAdmin since 1994, sometimes I feel way too old to still be working on this :)

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