"Unable to process PUT" to create ElasticSearch index with remote ElasticSearch

[htchief]

Infos:

• Used Zammad version: 1.5.x
• Used Zammad installation source: (source, package, …) Ubuntu DEB
• Operating system: Ubuntu 16.04
• Browser + version: CLI

Expected behavior:

• ElasticSearch Index should be built

Actual behavior:

• Unable to process PUT at https://**************************************:9243/zammad_production
  #<UserAgent::Result:0x00556d5d3b1a30 @success=false, @body=nil, @data=nil, @code=“400”, @content_type=nil, @error=“Client Error: #<Net::HTTPBadRequest 400 Bad Request readbody=true>!”>

Steps to reproduce the behavior:

Per: https://docs.zammad.org/en/latest/install-elasticsearch.html

• zammad run rails r “Setting.set(‘es_url’, ‘https://**************************************:9243’)”
• zammad run rails r “Setting.set(‘es_user’, ‘elastic’)”
• zammad run rails r “Setting.set(‘es_password’, ‘****************************’)”
• zammad run rails r “Setting.set(‘es_index’, ‘zammad’)”
• zammad run rails r “Setting.set(‘es_attachment_max_size_in_mb’, 50)”
• zammad run rake searchindex:rebuild

NOTE
Private information is obfucscated, but I’m using ElasticSearch version 5.6.4 hosted by ElasticCloud. I’ve ensured that ingest-attachment has been installed:

GET /_nodes?filter_path=.plugins.name,.plugins.version

{
  "nodes": {
    "aryxo0-XQp-WzMqrNE4uFA": {
      "plugins": [
        {
          "name": "found-elasticsearch",
          "version": "5.6.4"
        },
        {
          "name": "ingest-attachment",
          "version": "5.6.4"
        },
        {
          "name": "ingest-geoip",
          "version": "5.6.4"
        },
        {
          "name": "ingest-user-agent",
          "version": "5.6.4"
        },
        {
          "name": "repository-s3",
          "version": "5.6.4"
        },
        {
          "name": "x-pack",
          "version": "5.6.4"
        }
      ]
    },
    "x-19dgDxSsm8Bq1bsRN3nQ": {
      "plugins": [
        {
          "name": "found-elasticsearch",
          "version": "5.6.4"
        },
        {
          "name": "ingest-attachment",
          "version": "5.6.4"
        },
        {
          "name": "ingest-geoip",
          "version": "5.6.4"
        },
        {
          "name": "ingest-user-agent",
          "version": "5.6.4"
        },
        {
          "name": "repository-s3",
          "version": "5.6.4"
        },
        {
          "name": "x-pack",
          "version": "5.6.4"
        }
      ]
    },
    "zgFAZ_MLT-yXjImXd8LLpw": {
      "plugins": [
        {
          "name": "found-elasticsearch",
          "version": "5.6.4"
        },
        {
          "name": "ingest-attachment",
          "version": "5.6.4"
        },
        {
          "name": "ingest-geoip",
          "version": "5.6.4"
        },
        {
          "name": "ingest-user-agent",
          "version": "5.6.4"
        },
        {
          "name": "repository-s3",
          "version": "5.6.4"
        },
        {
          "name": "x-pack",
          "version": "5.6.4"
        }
      ]
    }
  }
}