[WIP] Add httpclient as alternative HTTP library

README.md

@@ -420,6 +420,20 @@ We try to support the last 3 minor versions, matching the [official support poli
 Kubernetes 1.2 and below have known issues and are unsupported.
 Kubernetes 1.3 presumed to still work although nobody is really testing on such old versions...
 
+### Changing the underlying HTTP library
+
+Kubeclient uses [rest_client](https://github.com/rest-client/rest-client) by default to perform HTTP requests. You can change this by specifying the `http_client_type` option when initializing `Kubeclient::Client`. Currently the only other option is [httpclient](https://github.com/nahi/httpclient).
+
+To use a different HTTP library, specify the `http_client_type` option when initializing `Kubeclient::Client`:
+
+```ruby
+client = Kubeclient::Client.new(
+  'https://localhost:8443/api/', "v1", http_client_type: 'httpclient'
+)
+```
+
+Using a different underlying HTTP library might have various advantages. For example, the `httpclient` gem is able to re-use HTTP connections between requests, as opposed to `rest_client`, which closes the HTTP connection after each request (see <https://github.com/rest-client/rest-client/issues/453>).
+
 ## Supported actions & examples:
 
 Summary of main CRUD actions:
@@ -548,7 +562,7 @@ Other formats are:
  - `:ros` (default) for `RecursiveOpenStruct`
  - `:parsed` for `JSON.parse`
  - `:parsed_symbolized` for `JSON.parse(..., symbolize_names: true)`
- - a class of your choice (this will instantiate a new instance of that class with the raw value of the response body) 
+ - a class of your choice (this will instantiate a new instance of that class with the raw value of the response body)
 
 ### Watch — Receive entities updates
 

kubeclient.gemspec

@@ -30,6 +30,7 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency 'googleauth', '~> 0.5.1'
   spec.add_development_dependency('mocha', '~> 1.5')
   spec.add_development_dependency 'openid_connect', '~> 1.1'
+  spec.add_development_dependency 'httpclient', '~> 2.0'
 
   spec.add_dependency 'jsonpath', '~> 1.0'
   spec.add_dependency 'rest-client', '~> 2.0'

lib/kubeclient.rb

@@ -8,10 +8,12 @@
 require 'kubeclient/exec_credentials'
 require 'kubeclient/gcp_auth_provider'
 require 'kubeclient/http_error'
+require 'kubeclient/httpclient_wrapper'
 require 'kubeclient/missing_kind_compatibility'
 require 'kubeclient/oidc_auth_provider'
 require 'kubeclient/resource'
 require 'kubeclient/resource_not_found_error'
+require 'kubeclient/rest_client_wrapper'
 require 'kubeclient/version'
 require 'kubeclient/watch_stream'
 

lib/kubeclient/common.rb

@@ -36,6 +36,8 @@ module ClientMixin
     DEFAULT_HTTP_PROXY_URI = nil
     DEFAULT_HTTP_MAX_REDIRECTS = 10
 
+    DEFAULT_HTTP_CLIENT_TYPE = 'rest_client'.freeze
+
     SEARCH_ARGUMENTS = {
       'labelSelector'   => :label_selector,
       'fieldSelector'   => :field_selector,
@@ -68,7 +70,8 @@ def initialize_client(
       timeouts: DEFAULT_TIMEOUTS,
       http_proxy_uri: DEFAULT_HTTP_PROXY_URI,
       http_max_redirects: DEFAULT_HTTP_MAX_REDIRECTS,
-      as: :ros
+      as: :ros,
+      http_client_type: DEFAULT_HTTP_CLIENT_TYPE
     )
       validate_auth_options(auth_options)
       handle_uri(uri, path)
@@ -86,6 +89,7 @@ def initialize_client(
       @http_proxy_uri = http_proxy_uri ? http_proxy_uri.to_s : nil
       @http_max_redirects = http_max_redirects
       @as = as
+      @http_client_type = http_client_type
 
       if auth_options[:bearer_token]
         bearer_token(@auth_options[:bearer_token])
@@ -282,6 +286,7 @@ def self.underscore_entity(entity_name)
         .downcase
     end
 
+    # *DEPRECATED:* Use +create_http_client+ instead.
     def create_rest_client(path = nil)
       path ||= @api_endpoint.path
       options = {
@@ -300,9 +305,44 @@ def create_rest_client(path = nil)
       RestClient::Resource.new(@api_endpoint.merge(path).to_s, options)
     end
 
+    # *DEPRECATED:* Use +http_client+ instead.
     def rest_client
-      @rest_client ||= begin
-        create_rest_client("#{@api_endpoint.path}/#{@api_version}")
+      http_client
+    end
+
+    # Returns the instance of the HTTP library used for making HTTP requests.
+    # By default this will be an instance of RestClient from `rest_client` gem.
+    # You can select a different HTTP library when creating and instance of +Kubeclient::Client+,
+    # see the +http_client_type+ option on +Kubeclient::Client.new+.
+    def http_client
+      http.client
+    end
+
+    # Creates and returns a new instance of a class that implements the interface
+    # defined by +HTTPWrapper+ class.
+    def create_http_client(url = nil, options = nil, http_client_type = nil)
+      url = "#{@api_endpoint}/#{@api_version}" if url.nil?
+      if options.nil?
+        options = {
+          ssl_ca_file: @ssl_options[:ca_file],
+          ssl_cert_store: @ssl_options[:cert_store],
+          verify_ssl: @ssl_options[:verify_ssl],
+          ssl_client_cert: @ssl_options[:client_cert],
+          ssl_client_key: @ssl_options[:client_key],
+          proxy: @http_proxy_uri,
+          max_redirects: @http_max_redirects,
+          user: @auth_options[:username],
+          password: @auth_options[:password],
+          open_timeout: @timeouts[:open],
+          read_timeout: @timeouts[:read]
+        }
+      end
+      http_client_type = @http_client_type if http_client_type.nil?
+
+      if http_client_type == 'httpclient'
+        HTTPClientWrapper.new(url, options)
+      else
+        RestClientWrapper.new(url, options)
       end
     end
 
@@ -352,8 +392,7 @@ def get_entities(entity_type, resource_name, options = {})
 
       ns_prefix = build_namespace_prefix(options[:namespace])
       response = handle_exception do
-        rest_client[ns_prefix + resource_name]
-          .get({ 'params' => params }.merge(@headers))
+        http.get(ns_prefix + resource_name, params: params, headers: @headers)
       end
       format_response(options[:as] || @as, response.body, entity_type)
     end
@@ -365,8 +404,7 @@ def get_entities(entity_type, resource_name, options = {})
     def get_entity(resource_name, name, namespace = nil, options = {})
       ns_prefix = build_namespace_prefix(namespace)
       response = handle_exception do
-        rest_client[ns_prefix + resource_name + "/#{name}"]
-          .get(@headers)
+        http.get(ns_prefix + resource_name + "/#{name}", headers: @headers)
       end
       format_response(options[:as] || @as, response.body)
     end
@@ -377,14 +415,10 @@ def delete_entity(resource_name, name, namespace = nil, delete_options: {})
       ns_prefix = build_namespace_prefix(namespace)
       payload = delete_options_hash.to_json unless delete_options_hash.empty?
       response = handle_exception do
-        rs = rest_client[ns_prefix + resource_name + "/#{name}"]
-        RestClient::Request.execute(
-          rs.options.merge(
-            method: :delete,
-            url: rs.url,
-            headers: { 'Content-Type' => 'application/json' }.merge(@headers),
-            payload: payload
-          )
+        http.delete(
+          ns_prefix + resource_name + "/#{name}",
+          body: payload,
+          headers: { 'Content-Type' => 'application/json' }.merge(@headers)
         )
       end
       format_response(@as, response.body)
@@ -403,8 +437,11 @@ def create_entity(entity_type, resource_name, entity_config)
       hash[:kind] = entity_type
       hash[:apiVersion] = @api_group + @api_version
       response = handle_exception do
-        rest_client[ns_prefix + resource_name]
-          .post(hash.to_json, { 'Content-Type' => 'application/json' }.merge(@headers))
+        http.post(
+          ns_prefix + resource_name,
+          body: hash.to_json,
+          headers: { 'Content-Type' => 'application/json' }.merge(@headers)
+        )
       end
       format_response(@as, response.body)
     end
@@ -413,20 +450,23 @@ def update_entity(resource_name, entity_config)
       name      = entity_config[:metadata][:name]
       ns_prefix = build_namespace_prefix(entity_config[:metadata][:namespace])
       response = handle_exception do
-        rest_client[ns_prefix + resource_name + "/#{name}"]
-          .put(entity_config.to_h.to_json, { 'Content-Type' => 'application/json' }.merge(@headers))
+        http.put(
+          ns_prefix + resource_name + "/#{name}",
+          body: entity_config.to_h.to_json,
+          headers: { 'Content-Type' => 'application/json' }.merge(@headers)
+        )
       end
       format_response(@as, response.body)
     end
 
     def patch_entity(resource_name, name, patch, strategy, namespace)
       ns_prefix = build_namespace_prefix(namespace)
       response = handle_exception do
-        rest_client[ns_prefix + resource_name + "/#{name}"]
-          .patch(
-            patch.to_json,
-            { 'Content-Type' => "application/#{strategy}+json" }.merge(@headers)
-          )
+        http.patch(
+          ns_prefix + resource_name + "/#{name}",
+          body: patch.to_json,
+          headers: { 'Content-Type' => "application/#{strategy}+json" }.merge(@headers)
+        )
       end
       format_response(@as, response.body)
     end
@@ -435,11 +475,11 @@ def apply_entity(resource_name, resource, field_manager:, force: true)
       name = "#{resource[:metadata][:name]}?fieldManager=#{field_manager}&force=#{force}"
       ns_prefix = build_namespace_prefix(resource[:metadata][:namespace])
       response = handle_exception do
-        rest_client[ns_prefix + resource_name + "/#{name}"]
-          .patch(
-            resource.to_json,
-            { 'Content-Type' => 'application/apply-patch+yaml' }.merge(@headers)
-          )
+        http.patch(
+          ns_prefix + resource_name + "/#{name}",
+          body: resource.to_json,
+          headers: { 'Content-Type' => 'application/apply-patch+yaml' }.merge(@headers)
+        )
       end
       format_response(@as, response.body)
     end
@@ -471,8 +511,11 @@ def get_pod_log(pod_name, namespace,
 
       ns = build_namespace_prefix(namespace)
       handle_exception do
-        rest_client[ns + "pods/#{pod_name}/log"]
-          .get({ 'params' => params }.merge(@headers))
+        http.get(
+          ns + "pods/#{pod_name}/log",
+          params: params,
+          headers: @headers
+        )
       end
     end
 
@@ -503,14 +546,17 @@ def proxy_url(kind, name, port, namespace = '')
           @entities[kind.to_s].resource_name
         end
       ns_prefix = build_namespace_prefix(namespace)
-      rest_client["#{ns_prefix}#{entity_name_plural}/#{name}:#{port}/proxy"].url
+      "#{@api_endpoint}/#{@api_version}/#{ns_prefix}#{entity_name_plural}/#{name}:#{port}/proxy"
     end
 
     def process_template(template)
       ns_prefix = build_namespace_prefix(template[:metadata][:namespace])
       response = handle_exception do
-        rest_client[ns_prefix + 'processedtemplates']
-          .post(template.to_h.to_json, { 'Content-Type' => 'application/json' }.merge(@headers))
+        http.post(
+          ns_prefix + 'processedtemplates',
+          body: template.to_h.to_json,
+          headers: { 'Content-Type' => 'application/json' }.merge(@headers)
+        )
       end
       JSON.parse(response)
     end
@@ -523,12 +569,19 @@ def api_valid?
     end
 
     def api
-      response = handle_exception { create_rest_client.get(@headers) }
+      response = handle_exception { create_http_client(@api_endpoint.to_s).get(headers: @headers) }
       JSON.parse(response)
     end
 
     private
 
+    # Returns an object that implements the interface defined by the +HTTPWrapper+ class.
+    def http
+      @http ||= begin
+        create_http_client
+      end
+    end
+
     IRREGULAR_NAMES = {
       # In a few cases, the given kind itself is still plural.
       # https://github.com/kubernetes/kubernetes/issues/8115
@@ -599,7 +652,7 @@ def load_entities
     end
 
     def fetch_entities
-      JSON.parse(handle_exception { rest_client.get(@headers) })
+      JSON.parse(handle_exception { http.get(headers: @headers) })
     end
 
     def bearer_token(bearer_token)

lib/kubeclient/http_wrapper.rb

@@ -0,0 +1,30 @@
+module Kubeclient
+  # Defines the common API for libraries to be used by Kubeclient for making HTTP requests.
+  # To create a wrapper for a library, create a new class that inherits from this class
+  # and override the +request+ method. See +RestClientWrapper+ or +HTTPClientWrapper+ for examples.
+  class HTTPWrapper
+    def delete(path = nil, **options)
+      request(:delete, path, **options)
+    end
+
+    def get(path = nil, **options)
+      request(:get, path, **options)
+    end
+
+    def patch(path = nil, **options)
+      request(:patch, path, **options)
+    end
+
+    def post(path = nil, **options)
+      request(:post, path, **options)
+    end
+
+    def put(path = nil, **options)
+      request(:put, path, **options)
+    end
+
+    def request
+      raise 'Must implement the `request` method.'
+    end
+  end
+end

lib/kubeclient/httpclient_wrapper.rb

@@ -0,0 +1,23 @@
+require_relative 'http_wrapper'
+
+module Kubeclient
+  # Wraps the API of +httpclient+ gem to be used by Kubeclient for making HTTP requests.
+  class HTTPClientWrapper < HTTPWrapper
+    def initialize(url, options)
+      @url = url
+      @options = options
+      @client = HTTPClient.new
+    end
+
+    attr_reader :client
+
+    def request(method, path = nil, **options)
+      uri = [@url, path].compact.join('/')
+      query = options[:params] if options.key?(:params)
+      body = options[:body] if options.key?(:body)
+      headers = options[:headers] if options.key(:headers)
+
+      @client.request(method, uri, query, body, headers)
+    end
+  end
+end

lib/kubeclient/rest_client_wrapper.rb

@@ -0,0 +1,35 @@
+require_relative 'http_wrapper'
+
+module Kubeclient
+  # Wraps the API of +rest_client+ gem to be used by Kubeclient for making HTTP requests.
+  class RestClientWrapper < HTTPWrapper
+    def initialize(url, options)
+      @client = RestClient::Resource.new(url, options)
+    end
+
+    attr_reader :client
+
+    def request(method, path = nil, **options)
+      url = path.nil? ? @client.url : @client[path].url
+      headers_with_params = create_headers_with_params(options[:headers], options[:params])
+      payload = options[:body]
+
+      execute_options = @client.options.merge(
+        method: method,
+        url: url,
+        headers: headers_with_params,
+        payload: payload
+      )
+      RestClient::Request.execute(execute_options)
+    end
+
+    private
+
+    # In RestClient, you pass params hash inside the headers hash, in :params key.
+    def create_headers_with_params(headers, params)
+      headers_with_params = {}.merge(headers || {})
+      headers_with_params[:params] = params if params
+      headers_with_params
+    end
+  end
+end