Elastic Search Give an error No alive nodes found in your cluster

I have found this error and solved it by following steps:

1. Comments the plugin setting on app/etc/env.php file.

   'system' => [
   'default' => [
     /* 'smile_elasticsuite_core_base_settings' => [
    'es_client' => [
     'servers' => 'node-1:9200,node-2:9200',
     'enable_https_mode' => '0',
     'enable_http_auth' => '0',
     'http_auth_user' => '',
     'http_auth_pwd' => ''
      ]
     ] */
    ]
   ]
   

2. Start the server.

3. upgrade magento

   php bin/magento setup:upgrade 
   

I also facing the same problem. I was specified in host 'myhostaddress:9200'. Change it with IP of your Elasticsearch host server like '127.0.0.1:9200' . It resolve my problem.

I found the error.Error is coming due to space before node.name and cluster.name.Remove the space and its working fine.

Updated elasticsearch.yml file

# ======================== Elasticsearch Configuration =========================
#
# NOTE: Elasticsearch comes with reasonable defaults for most settings.
#       Before you set out to tweak and tune the configuration, make sure you
#       understand what are you trying to accomplish and the consequences.
#
# The primary way of configuring a node is via this file. This template lists
# the most important settings you may want to configure for a production cluster.
#
# Please see the documentation for further information on configuration options:
# <http://www.elastic.co/guide/en/elasticsearch/reference/current/setup-configuration.html>
#
# ---------------------------------- Cluster -----------------------------------
#
# Use a descriptive name for your cluster:
#
cluster.name: my-application-shakedeal
#
# ------------------------------------ Node ------------------------------------
#
# Use a descriptive name for the node:
#
node.name: shakedeal-1
#
# Add custom attributes to the node:
#
# node.rack: r1
#
# ----------------------------------- Paths ------------------------------------
#
# Path to directory where to store the data (separate multiple locations by comma):
#
# path.data: /path/to/data
#
# Path to log files:
#
# path.logs: /path/to/logs
#
# ----------------------------------- Memory -----------------------------------
#
# Lock the memory on startup:
#
# bootstrap.memory_lock: true
#
# Make sure that the `ES_HEAP_SIZE` environment variable is set to about half the memory
# available on the system and that the owner of the process is allowed to use this limit.
#
# Elasticsearch performs poorly when the system is swapping the memory.
#
# ---------------------------------- Network -----------------------------------
#
# Set the bind address to a specific IP (IPv4 or IPv6):
#
network.host: 127.0.0.1
network.bind_host: IP_ADDRESS
#
# Set a custom port for HTTP:
#
# http.port: 9200
#
# For more information, see the documentation at:
# <http://www.elastic.co/guide/en/elasticsearch/reference/current/modules-network.html>
#
# --------------------------------- Discovery ----------------------------------
#
# Pass an initial list of hosts to perform discovery when new node is started:
# The default list of hosts is ["127.0.0.1", "[::1]"]
#
# discovery.zen.ping.unicast.hosts: ["host1", "host2"]
#
# Prevent the "split brain" by configuring the majority of nodes (total number of nodes / 2 + 1):
#
# discovery.zen.minimum_master_nodes: 3
#
# For more information, see the documentation at:
# <http://www.elastic.co/guide/en/elasticsearch/reference/current/modules-discovery.html>
#
# ---------------------------------- Gateway -----------------------------------
#
# Block initial recovery after a full cluster restart until N nodes are started:
#
# gateway.recover_after_nodes: 3
#
# For more information, see the documentation at:
# <http://www.elastic.co/guide/en/elasticsearch/reference/current/modules-gateway.html>
#
# ---------------------------------- Various -----------------------------------
#
# Disable starting multiple nodes on a single system:
#
# node.max_local_storage_nodes: 1
#
# Require explicit names when deleting indices:
#
# action.destructive_requires_name: true

PHP Code

 <?php
    require 'vendor/autoload.php';
    $indexParams = [
        'index' => 'my_index',
        'body' => [
            'settings' => [
                'number_of_shards' => 5,
                'number_of_replicas' => 1
            ]
        ]
    ];

    $client = Elasticsearch\ClientBuilder::create()
        ->setSSLVerification(false)
        ->setHosts(["IP_ADDRESS:9200"])->build();  
    $response = ''; 
    try {
        /* Create the index */
        $response = $client->indices()->create($indexParams);
        print_r($response);

        print_r($response);

    } catch(Exception $e) {
        echo "Exception : ".$e->getMessage();
    }
    die('End : Elastic Search');

?>

Success Response :

 Array
 (
    [acknowledged] => 1
 )