feat: Implement custom bootstrapping on startup

README.md

@@ -79,6 +79,7 @@ Argument | Description | Required? |  Type |  Default Value|
 `backup_file` | Filename to store the last known state from the Unleash server. Best to not change this from the default. | N | String | `Dir.tmpdir + "/unleash-#{app_name}-repo.json` |
 `logger` | Specify a custom `Logger` class to handle logs for the Unleash client. | N | Class | `Logger.new(STDOUT)` |
 `log_level` | Change the log level for the `Logger` class. Constant from `Logger::Severity`. | N | Constant | `Logger::WARN` |
+`bootstrapper` | Defines a bootstrapper object that unleash will use to get a list of toggles on load before it reads them from the unleash server. This is useful for loading large states on startup without hitting the network. Bootstrapping classes are provided for URL and file reading but you can implement your own for other sources of toggles. | N | Class | `nil` |
 
 For in a more in depth look, please see `lib/unleash/configuration.rb`.
 
@@ -88,8 +89,14 @@ For in a more in depth look, please see `lib/unleash/configuration.rb`.
 ```ruby
 require 'unleash'
 require 'unleash/context'
+require 'unleash/bootstrap'
 
-@unleash = Unleash::Client.new(app_name: 'my_ruby_app', url: 'http://unleash.herokuapp.com/api', custom_http_headers: {'Authorization': '<API token>'})
+@unleash = Unleash::Client.new(
+            app_name: 'my_ruby_app',
+            url: 'http://unleash.herokuapp.com/api',
+            custom_http_headers: { 'Authorization': '<API token>' },
+            bootstrapper: Unleash::FileBootStrapper.new('./default-toggles.json')
+          )
 
 feature_name = "AwesomeFeature"
 unleash_context = Unleash::Context.new
@@ -109,12 +116,15 @@ end
 Put in `config/initializers/unleash.rb`:
 
 ```ruby
+require 'unleash/bootstrap'
+
 Unleash.configure do |config|
   config.app_name = Rails.application.class.parent.to_s
   config.url      = 'http://unleash.herokuapp.com/api'
   # config.instance_id = "#{Socket.gethostname}"
   config.logger   = Rails.logger
   config.environment = Rails.env
+  config.bootstrapper = Unleash::FileBootStrapper.new('./default-toggles.json')
 end
 
 UNLEASH = Unleash::Client.new

examples/bootstrap.rb

@@ -0,0 +1,50 @@
+#!/usr/bin/env ruby
+
+require 'unleash'
+require 'unleash/context'
+require 'unleash/bootstrap'
+
+puts ">> START bootstrap.rb"
+
+@unleash = Unleash::Client.new(
+  url: 'http://unleash.herokuapp.com/api',
+  custom_http_headers: { 'Authorization': '943ca9171e2c884c545c5d82417a655fb77cec970cc3b78a8ff87f4406b495d0' },
+  app_name: 'bootstrap-test',
+  instance_id: 'local-test-cli',
+  refresh_interval: 2,
+  metrics_interval: 2,
+  retry_limit: 2,
+  bootstrapper: Unleash::FileBootStrapper.new('./examples/default-toggles.json')
+)
+
+# feature_name = "AwesomeFeature"
+feature_name = "featureX"
+unleash_context = Unleash::Context.new
+unleash_context.user_id = 123
+
+sleep 1
+3.times do
+  if @unleash.is_enabled?(feature_name, unleash_context)
+    puts "> #{feature_name} is enabled"
+  else
+    puts "> #{feature_name} is not enabled"
+  end
+  sleep 1
+  puts "---"
+  puts ""
+  puts ""
+end
+
+sleep 3
+feature_name = "foobar"
+if @unleash.is_enabled?(feature_name, unleash_context, true)
+  puts "> #{feature_name} is enabled"
+else
+  puts "> #{feature_name} is not enabled"
+end
+
+puts "> shutting down client..."
+
+@unleash.shutdown
+
+puts ">> END bootstrap.rb"

examples/default-toggles.json

@@ -0,0 +1,43 @@
+
+{
+    "version": 1,
+    "features": [
+    {
+        "name": "featureX",
+        "enabled": true,
+        "strategies": [
+            {
+                "name": "default"
+            }
+        ]
+    },
+    {
+        "name": "featureY",
+        "enabled": false,
+        "strategies": [
+            {
+                "name": "baz",
+                "parameters": {
+                    "foo": "bar"
+                }
+            }
+        ]
+
+    },
+    {
+        "name": "featureZ",
+        "enabled": true,
+        "strategies": [
+            {
+                "name": "default"
+            },
+            {
+                "name": "hola",
+                "parameters": {
+                    "name": "val"
+                }
+            }
+        ]
+
+    }
+]}

lib/unleash/bootstrap.rb

@@ -0,0 +1,55 @@
+require 'unleash/configuration'
+require 'unleash/feature_toggle'
+require 'logger'
+require 'time'
+require 'net/http'
+require 'uri'
+
+module Unleash
+  class FileBootStrapper
+    attr_accessor :file_path
+
+    def initialize(file_path)
+      self.file_path = file_path
+    end
+
+    def read
+      file_content = File.read(self.file_path)
+      bootstrap_hash = JSON.parse(file_content)
+      Unleash.extract_bootstrap(bootstrap_hash)
+    end
+  end
+
+  class UrlBootStrapper
+    attr_accessor :uri, :headers
+
+    def initialize(uri, headers)
+      self.uri = URI(uri)
+      self.headers = headers
+    end
+
+    def read
+      request = Net::HTTP::Get.new(self.uri, self.build_headers(self.headers))
+
+      http = Net::HTTP.new(uri.host, uri.port)
+      http.use_ssl = true if uri.scheme == 'https'
+      http.open_timeout = Unleash.configuration.timeout
+      http.read_timeout = Unleash.configuration.timeout
+
+      http.request(request)
+    end
+
+    def build_headers(headers = nil)
+      headers = (headers || {}).dup
+      headers['Content-Type'] = 'application/json'
+
+      headers
+    end
+  end
+
+  def self.extract_bootstrap(bootstrap_hash)
+    raise NotImplemented, "The provided bootstrap doesn't seem to be a valid set of toggles" if bootstrap_hash['version'] < 1
+
+    bootstrap_hash['features']
+  end
+end

lib/unleash/configuration.rb

@@ -18,7 +18,8 @@ class Configuration
       :metrics_interval,
       :backup_file,
       :logger,
-      :log_level
+      :log_level,
+      :bootstrapper
 
     def initialize(opts = {})
       ensure_valid_opts(opts)
@@ -92,6 +93,7 @@ def set_defaults
       self.retry_limit      = 5
       self.backup_file      = nil
       self.log_level        = Logger::WARN
+      self.bootstrapper     = nil
 
       self.custom_http_headers = {}
     end

lib/unleash/toggle_fetcher.rb

@@ -4,20 +4,26 @@
 
 module Unleash
   class ToggleFetcher
-    attr_accessor :toggle_cache, :toggle_lock, :toggle_resource, :etag, :retry_count
+    attr_accessor :toggle_cache, :toggle_lock, :toggle_resource, :etag, :retry_count, :bootstrapper
 
     def initialize
       self.etag = nil
       self.toggle_cache = nil
       self.toggle_lock = Mutex.new
       self.toggle_resource = ConditionVariable.new
       self.retry_count = 0
+      self.bootstrapper = Unleash.configuration.bootstrapper
 
       # start by fetching synchronously, and failing back to reading the backup file.
       begin
-        fetch
+        if !self.bootstrapper.nil? # if the consumer provides a bootstrapper, we're going to assume they want to use it
+          synchronize_with_local_cache! self.bootstrapper.read
+          update_running_client!
+        else
+          fetch
+        end
       rescue StandardError => e
-        Unleash.logger.warn "ToggleFetcher was unable to fetch from the network, attempting to read from backup file."
+        Unleash.logger.warn "ToggleFetcher was unable to fetch from the network or bootstrap, attempting to read from backup file."
         Unleash.logger.debug "Exception Caught: #{e}"
         read!
       end

spec/unleash/bootstrap-resources/features-v1.json

@@ -0,0 +1,43 @@
+
+{
+    "version": 1,
+    "features": [
+    {
+        "name": "featureX",
+        "enabled": true,
+        "strategies": [
+            {
+                "name": "default"
+            }
+        ]
+    },
+    {
+        "name": "featureY",
+        "enabled": false,
+        "strategies": [
+            {
+                "name": "baz",
+                "parameters": {
+                    "foo": "bar"
+                }
+            }
+        ]
+
+    },
+    {
+        "name": "featureZ",
+        "enabled": true,
+        "strategies": [
+            {
+                "name": "default"
+            },
+            {
+                "name": "hola",
+                "parameters": {
+                    "name": "val"
+                }
+            }
+        ]
+
+    }
+]}

spec/unleash/bootstrap_spec.rb

@@ -0,0 +1,35 @@
+require 'spec_helper'
+require 'unleash/constraint'
+require 'unleash/bootstrap'
+require 'json'
+
+RSpec.describe Unleash::Client do
+  before do
+    Unleash.configuration = Unleash::Configuration.new
+    Unleash.logger = Unleash.configuration.logger
+  end
+
+  describe 'Bootstrap' do
+    it 'loads bootstrap toggle correctly from file' do
+      bootstrapper = Unleash::FileBootStrapper.new('./spec/unleash/bootstrap-resources/features-v1.json')
+      bootstrapper.read
+    end
+
+    it 'loads bootstrap toggle correctly from URL' do
+      WebMock.stub_request(:get, "http://test-url/bootstrap-goodness")
+        .with(
+          headers: {
+            'Accept' => '*/*',
+            'Accept-Encoding' => 'gzip;q=1.0,deflate;q=0.6,identity;q=0.3',
+            'Content-Type' => 'application/json',
+            'Host' => 'test-url',
+            'User-Agent' => 'Ruby'
+          }
+        )
+        .to_return(status: 200, body: "", headers: {})
+
+      bootstrapper = Unleash::UrlBootStrapper.new('http://test-url/bootstrap-goodness', nil)
+      bootstrapper.read
+    end
+  end
+end