feat: read backup file and bootstrap for streaming

lib/unleash/backup_file_reader.rb

@@ -0,0 +1,30 @@
+require 'unleash/configuration'
+require 'json'
+
+module Unleash
+  class BackupFileReader
+    def self.read!
+      Unleash.logger.debug "read!()"
+
+      backup_file = Unleash.configuration.backup_file
+      return nil unless File.exist?(backup_file)
+
+      File.read(backup_file)
+    rescue IOError => e
+      # :nocov:
+      Unleash.logger.error "Unable to read the backup_file: #{e}"
+      # :nocov:
+      nil
+    rescue JSON::ParserError => e
+      # :nocov:
+      Unleash.logger.error "Unable to parse JSON from existing backup_file: #{e}"
+      # :nocov:
+      nil
+    rescue StandardError => e
+      # :nocov:
+      Unleash.logger.error "Unable to extract valid data from backup_file. Exception thrown: #{e}"
+      # :nocov:
+      nil
+    end
+  end
+end

lib/unleash/streaming_client_executor.rb

@@ -1,4 +1,6 @@
 require 'unleash/streaming_event_processor'
+require 'unleash/bootstrap/handler'
+require 'unleash/backup_file_reader'
 require 'unleash/util/event_source_wrapper'
 
 module Unleash
@@ -10,6 +12,20 @@ def initialize(name, engine)
       self.event_source = nil
       self.event_processor = Unleash::StreamingEventProcessor.new(engine)
       self.running = false
+
+      begin
+        # if bootstrap configuration is available, initialize. Otherwise read backup file
+        if Unleash.configuration.use_bootstrap?
+          bootstrap(engine)
+        else
+          read_backup_file!(engine)
+        end
+      rescue StandardError => e
+        # fail back to reading the backup file
+        Unleash.logger.warn "StreamingClientExecutor was unable to initialize, attempting to read from backup file."
+        Unleash.logger.debug "Exception Caught: #{e}"
+        read_backup_file!(engine)
+      end
     end
 
     def run(&_block)
@@ -81,5 +97,18 @@ def handle_event(event)
       Unleash.logger.error "Streaming client #{self.name} threw exception #{e.class}: '#{e}'"
       Unleash.logger.debug "stacktrace: #{e.backtrace}"
     end
+
+    def read_backup_file!(engine)
+      backup_data = Unleash::BackupFileReader.read!
+      engine.take_state(backup_data) if backup_data
+    end
+
+    def bootstrap(engine)
+      bootstrap_payload = Unleash::Bootstrap::Handler.new(Unleash.configuration.bootstrap_config).retrieve_toggles
+      engine.take_state(bootstrap_payload)
+
+      # reset Unleash.configuration.bootstrap_data to free up memory, as we will never use it again
+      Unleash.configuration.bootstrap_config = nil
+    end
   end
 end

lib/unleash/toggle_fetcher.rb

@@ -1,6 +1,7 @@
 require 'unleash/configuration'
 require 'unleash/bootstrap/handler'
 require 'unleash/backup_file_writer'
+require 'unleash/backup_file_reader'
 require 'net/http'
 require 'json'
 require 'yggdrasil_engine'
@@ -27,7 +28,7 @@ def initialize(engine)
         # fail back to reading the backup file
         Unleash.logger.warn "ToggleFetcher was unable to fetch from the network, attempting to read from backup file."
         Unleash.logger.debug "Exception Caught: #{e}"
-        read!
+        read_backup_file!
       end
 
       # once initialized, somewhere else you will want to start a loop with fetch()
@@ -71,25 +72,9 @@ def update_engine_state!(toggle_data)
       Unleash.logger.error "Failed to hydrate state: #{e.backtrace}"
     end
 
-    def read!
-      Unleash.logger.debug "read!()"
-      backup_file = Unleash.configuration.backup_file
-      return nil unless File.exist?(backup_file)
-
-      backup_data = File.read(backup_file)
-      update_engine_state!(backup_data)
-    rescue IOError => e
-      # :nocov:
-      Unleash.logger.error "Unable to read the backup_file: #{e}"
-      # :nocov:
-    rescue JSON::ParserError => e
-      # :nocov:
-      Unleash.logger.error "Unable to parse JSON from existing backup_file: #{e}"
-      # :nocov:
-    rescue StandardError => e
-      # :nocov:
-      Unleash.logger.error "Unable to extract valid data from backup_file. Exception thrown: #{e}"
-      # :nocov:
+    def read_backup_file!
+      backup_data = Unleash::BackupFileReader.read!
+      update_engine_state!(backup_data) if backup_data
     end
 
     def bootstrap

spec/unleash/streaming_client_executor_spec.rb

@@ -0,0 +1,160 @@
+RSpec.describe Unleash::StreamingClientExecutor do
+  subject(:streaming_executor) { Unleash::StreamingClientExecutor.new(executor_name, engine) }
+
+  unless RUBY_ENGINE == 'jruby'
+    before do
+      Unleash.configure do |config|
+        config.url      = 'http://streaming-test-url/'
+        config.app_name = 'streaming-test-app'
+        config.instance_id = 'rspec/streaming'
+        config.disable_metrics = true
+        config.experimental_mode = { type: 'streaming' }
+      end
+
+      WebMock.stub_request(:post, "http://streaming-test-url/client/register")
+        .to_return(status: 200, body: "", headers: {})
+
+      Unleash.logger = Unleash.configuration.logger
+    end
+
+    after do
+      WebMock.reset!
+      File.delete(Unleash.configuration.backup_file) if File.exist?(Unleash.configuration.backup_file)
+
+      # Reset configuration to prevent interference with other tests
+      Unleash.configuration.bootstrap_config = nil
+      Unleash.configuration.experimental_mode = nil
+      Unleash.configuration.disable_metrics = false
+    end
+
+    describe '.new' do
+      let(:engine) { YggdrasilEngine.new }
+      let(:executor_name) { 'streaming_client_executor_spec' }
+
+      context 'when there are problems connecting to streaming endpoint' do
+        let(:backup_toggles) do
+          {
+            version: 1,
+            features: [
+              {
+                name: "backup-feature",
+                description: "Feature from backup",
+                enabled: true,
+                strategies: [{
+                  name: "default"
+                }]
+              }
+            ]
+          }
+        end
+
+        before do
+          backup_file = Unleash.configuration.backup_file
+
+          # manually create a stub cache on disk, so we can test that we read it correctly later.
+          File.open(backup_file, "w") do |file|
+            file.write(backup_toggles.to_json)
+          end
+
+          WebMock.stub_request(:get, "http://streaming-test-url/client/streaming")
+            .to_return(status: 500, body: "Internal Server Error", headers: {})
+
+          streaming_executor
+        end
+
+        it 'reads the backup file for values' do
+          enabled = engine.enabled?('backup-feature', {})
+          expect(enabled).to eq(true)
+        end
+      end
+
+      context 'when bootstrap is configured' do
+        let(:bootstrap_data) do
+          {
+            version: 1,
+            features: [
+              {
+                name: "bootstrap-feature",
+                enabled: true,
+                strategies: [{ name: "default" }]
+              }
+            ]
+          }
+        end
+
+        let(:bootstrap_config) do
+          Unleash::Bootstrap::Configuration.new({
+            'data' => bootstrap_data.to_json
+          })
+        end
+
+        before do
+          Unleash.configuration.bootstrap_config = bootstrap_config
+
+          WebMock.stub_request(:get, "http://streaming-test-url/client/streaming")
+            .to_return(status: 200, body: "", headers: {})
+
+          streaming_executor
+        end
+
+        after do
+          Unleash.configuration.bootstrap_config = nil
+        end
+
+        it 'uses bootstrap data on initialization' do
+          enabled = engine.enabled?('bootstrap-feature', {})
+          expect(enabled).to eq(true)
+        end
+
+        it 'clears bootstrap config after use' do
+          expect(Unleash.configuration.bootstrap_config).to be_nil
+        end
+      end
+
+      context 'when bootstrap fails and backup file exists' do
+        let(:invalid_bootstrap_config) do
+          Unleash::Bootstrap::Configuration.new({
+            'data' => 'invalid json'
+          })
+        end
+
+        let(:fallback_toggles) do
+          {
+            version: 1,
+            features: [
+              {
+                name: "fallback-feature",
+                enabled: true,
+                strategies: [{ name: "default" }]
+              }
+            ]
+          }
+        end
+
+        before do
+          backup_file = Unleash.configuration.backup_file
+
+          File.open(backup_file, "w") do |file|
+            file.write(fallback_toggles.to_json)
+          end
+
+          Unleash.configuration.bootstrap_config = invalid_bootstrap_config
+
+          WebMock.stub_request(:get, "http://streaming-test-url/client/streaming")
+            .to_return(status: 500, body: "", headers: {})
+
+          streaming_executor
+        end
+
+        after do
+          Unleash.configuration.bootstrap_config = nil
+        end
+
+        it 'falls back to reading backup file when bootstrap fails' do
+          enabled = engine.enabled?('fallback-feature', {})
+          expect(enabled).to eq(true)
+        end
+      end
+    end
+  end
+end