Add Feature Flags support to DEV (#7996)

* Create tables for Flipper gem

* Enable Flipper gem

* Remove concurrent ruby from Gemfile

* Add Flipper UI

* Codeland landing page

* Remove codeland controller and sample page

* Remove oops

* Rename Flipper-UI endpoint

* Wrap Flipper in a FeatureFlag module

* [deploy] Lock node to 12.16 (#8057)

Co-authored-by: Mac Siri <krairit.siri@gmail.com>

Gemfile

@@ -44,6 +44,9 @@ gem "fastly", "~> 2.5" # Client library for the Fastly acceleration system
 gem "feedjira", "~> 3.1" # A feed fetching and parsing library
 gem "field_test", "~> 0.3" # A/B testing
 gem "figaro", "~> 1.2" # Simple, Heroku-friendly Rails app configuration using ENV and a single YAML file
+gem "flipper", "~> 0.17.2" # Feature flipping / flags for Ruby
+gem "flipper-active_record", "~> 0.17.2" # Store Flipper flags in ActiveRecord
+gem "flipper-ui", "~> 0.17.2"
 gem "fog-aws", "~> 3.6" # 'fog' gem to support Amazon Web Services
 gem "front_matter_parser", "~> 0.2" # Parse a front matter from syntactically correct strings or files
 gem "gemoji", "~> 4.0.0.rc2" # Character information and metadata for standard and custom emoji

Gemfile.lock

@@ -323,6 +323,15 @@ GEM
       thor (>= 0.14.0, < 2)
     fix-db-schema-conflicts (3.0.3)
       rubocop (>= 0.38.0)
+    flipper (0.17.2)
+    flipper-active_record (0.17.2)
+      activerecord (>= 4.2, < 7)
+      flipper (~> 0.17.2)
+    flipper-ui (0.17.2)
+      erubi (>= 1.0.0, < 2.0.0)
+      flipper (~> 0.17.2)
+      rack (>= 1.4, < 3)
+      rack-protection (>= 1.5.3, < 2.1.0)
     fog-aws (3.6.4)
       fog-core (~> 2.1)
       fog-json (~> 1.1)
@@ -891,6 +900,9 @@ DEPENDENCIES
   field_test (~> 0.3)
   figaro (~> 1.2)
   fix-db-schema-conflicts (~> 3.0)
+  flipper (~> 0.17.2)
+  flipper-active_record (~> 0.17.2)
+  flipper-ui (~> 0.17.2)
   fog-aws (~> 3.6)
   front_matter_parser (~> 0.2)
   gemoji (~> 4.0.0.rc2)

app/helpers/feature_flag.rb

@@ -0,0 +1,7 @@
+module FeatureFlag
+  extend self # rubocop:disable Style/ModuleFunction
+
+  def enabled?(feature_name, *args)
+    Flipper[feature_name].enabled?(*args)
+  end
+end

app/models/user.rb

@@ -462,6 +462,10 @@ class User < ApplicationRecord
     RateLimitChecker.new(self)
   end
 
+  def flipper_id
+    "User:#{id}"
+  end
+
   private
 
   def estimate_default_language

config/initializers/flipper.rb

@@ -0,0 +1,15 @@
+Flipper.configure do |config|
+  config.default do
+    # pick an adapter, this uses memory, any will do
+    adapter = Flipper::Adapters::ActiveRecord.new
+
+    # pass adapter to handy DSL instance
+    Flipper.new(adapter)
+  end
+end
+
+Flipper::UI.configure do |config|
+  # Provide guidance on format for user ids
+  config.actors.title = "Actor (ex: User:123)"
+  config.actors.description = "ex: User:123"
+end

config/routes.rb

@@ -42,6 +42,7 @@ Rails.application.routes.draw do
 
     authenticate :user, ->(user) { user.has_role?(:tech_admin) } do
       mount Blazer::Engine, at: "blazer"
+      mount Flipper::UI.app(Flipper), at: "feature_flags"
     end
 
     resources :articles, only: %i[index show update]

db/migrate/20200519220213_create_flipper_tables.rb

@@ -0,0 +1,22 @@
+class CreateFlipperTables < ActiveRecord::Migration[5.2]
+  def self.up
+    create_table :flipper_features do |t|
+      t.string :key, null: false
+      t.timestamps null: false
+    end
+    add_index :flipper_features, :key, unique: true
+
+    create_table :flipper_gates do |t|
+      t.string :feature_key, null: false
+      t.string :key, null: false
+      t.string :value
+      t.timestamps null: false
+    end
+    add_index :flipper_gates, [:feature_key, :key, :value], unique: true
+  end
+
+  def self.down
+    drop_table :flipper_gates
+    drop_table :flipper_features
+  end
+end

db/schema.rb

@@ -506,6 +506,22 @@ ActiveRecord::Schema.define(version: 2020_05_25_125611) do
     t.index ["participant_type", "participant_id", "experiment"], name: "index_field_test_memberships_on_participant", unique: true
   end
 
+  create_table "flipper_features", force: :cascade do |t|
+    t.datetime "created_at", null: false
+    t.string "key", null: false
+    t.datetime "updated_at", null: false
+    t.index ["key"], name: "index_flipper_features_on_key", unique: true
+  end
+
+  create_table "flipper_gates", force: :cascade do |t|
+    t.datetime "created_at", null: false
+    t.string "feature_key", null: false
+    t.string "key", null: false
+    t.datetime "updated_at", null: false
+    t.string "value"
+    t.index ["feature_key", "key", "value"], name: "index_flipper_gates_on_feature_key_and_key_and_value", unique: true
+  end
+
   create_table "follows", id: :serial, force: :cascade do |t|
     t.boolean "blocked", default: false, null: false
     t.datetime "created_at"