Add support for PUT _ccr/follow

README.md

@@ -164,6 +164,11 @@ ES 8
 ES_PORT=9208 rake test
 ```
 
+CCR tests:
+```
+ES_PORT=9208 ES_REPLICA_PORT=9209 rake test
+```
+
 ES 5
 ```
 ES_PORT=9205 rake test

lib/elastomer_client/client/ccr.rb

@@ -0,0 +1,41 @@
+# frozen_string_literal: true
+
+module ElastomerClient
+  class Client
+
+    # Returns a CCR instance
+    def ccr
+      Ccr.new(self)
+    end
+
+    class Ccr
+      # Create a new Ccr for initiating requests for cross cluster replication.
+      # More context: https://www.elastic.co/guide/en/elasticsearch/reference/current/ccr-apis.html
+      #
+      # client     - ElastomerClient::Client used for HTTP requests to the server
+      def initialize(client)
+        @client = client
+      end
+
+      attr_reader :client
+
+      # Creates a new follower index for the provided leader index on the remote cluster.
+      #
+      # follower_index - String name of the follower index to create
+      # body           - Hash of the request body
+      #   :remote_cluster - String name of the remote cluster. Required.
+      #   :leader_index   - String name of the leader index. Required.
+      # params         - Hash of query parameters
+      #
+      # Examples
+      #
+      #   ccr.follow("follower_index", { leader_index: "leader_index", remote_cluster: "leader" })
+      #
+      # See https://www.elastic.co/guide/en/elasticsearch/reference/current/ccr-put-follow.html
+      def follow(follower_index, body, params = {})
+        response = client.put "/#{follower_index}/_ccr/follow", params.merge(body:, action: "follow", rest_api: "ccr")
+        response.body
+      end
+    end
+  end
+end

script/setup-ccr

@@ -65,7 +65,7 @@ case "$1" in
       "persistent": {
         "cluster": {
           "remote": {
-            "cluster_one": {
+            "leader": {
               "seeds": ["es8.13:9300"]
             }
           }

test/client/ccr_test.rb

@@ -0,0 +1,39 @@
+# frozen_string_literal: true
+
+require_relative "../test_helper"
+
+describe ElastomerClient::Client::Ccr do
+  before do
+    skip "Cannot test Ccr API without a replica cluster" unless $replica_client.available?
+
+    @leader_index = $client.index("leader_index")
+    @follower_index = $replica_client.index("follower_index")
+    if @leader_index.exists?
+      @leader_index.delete
+    end
+    if @follower_index.exists?
+      @follower_index.delete
+    end
+    @leader_index.create(default_index_settings)
+    wait_for_index(@leader_index.name, "green")
+
+    @leader_index.docs.index(document_wrapper("book", { _id: 1, title: "Book 1" }))
+    @leader_index.refresh
+  end
+
+  after do
+    @leader_index.delete if @leader_index.exists?
+    @follower_index.delete if @follower_index.exists?
+  end
+
+  it "successfully follows a leader index" do
+    ccr = $replica_client.ccr
+
+    ccr.follow(@follower_index.name, { leader_index: @leader_index.name, remote_cluster: "leader" })
+    wait_for_index(@follower_index.name, "green")
+    doc = @follower_index.docs.get(id: 1, type: "book")
+
+    assert_equal "Book 1", doc["_source"]["title"]
+  end
+
+end

test/test_helper.rb

@@ -46,6 +46,19 @@
 
 puts "Elasticsearch version is #{$client.version}"
 
+# Create client instance for replica cluster
+$replica_client_params = {
+  port: ENV.fetch("ES_REPLICA_PORT", 9201),
+  read_timeout: 10,
+  open_timeout: 1,
+  opaque_id: false,
+  strict_params: true,
+  compress_body: true
+}
+$replica_client = ElastomerClient::Client.new(**$replica_client_params)
+
+puts "Replica server is unavailable at #{$replica_client.url}" unless $replica_client.available?
+
 # remove any lingering test indices from the cluster
 Minitest.after_run do
   $client.cluster.indices.keys.each do |name|