.env

ELASTICSEARCH_URL=https://****
AWS_REGION=****
AWS_ACCESS_KEY_ID=****
AWS_SECRET_ACCESS_KEY=****

elasticsearch_access_policy.json

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Principal": {
        "AWS": "arn:aws:iam::XXXXXXXX:user/XXXXXXXX"
      },
      "Action": "es:*",
      "Resource": "arn:aws:es:us-east-2:XXXXXXXX:domain/XXXXXXXX/*"
    },
    {
      "Sid": "",
      "Effect": "Allow",
      "Principal": {
        "AWS": "*"
      },
      "Action": "es:*",
      "Resource": "arn:aws:es:us-east-2:XXXXXXXX:domain/XXXXXXXX/*",
      "Condition": {
        "IpAddress": {
          "aws:SourceIp": "***.***.***.***"
        }
      }
    }
  ]
}

elasticsearch_config.rb

if ENV['ELASTICSEARCH_URL'].present?
  Searchkick.aws_credentials = {
    access_key_id: ENV['AWS_ACCESS_KEY_ID'],
    secret_access_key: ENV['AWS_SECRET_ACCESS_KEY'],
    region: ENV['AWS_REGION']
  }
end

Gemfile

gem 'elasticsearch', '~> 6.2.0'
gem 'searchkick', '~> 3.1'
gem 'faraday_middleware-aws-sigv4', '~> 0.2.4'