APERTA-9087 Coerce and enforce arrays in env vars to reduce complexity

.env

@@ -3,6 +3,8 @@ APP_NAME=Aperta
 CAPYBARA_SERVER_PORT=31337
 RAILS_SECRET_TOKEN=secret-token-goes-here
 REDIS_PROVIDER="redis://localhost:6379"
+REDIS_SENTINEL_ENABLED='false'
+REDIS_SENTINELS="['server1', 'server2']"
 SIDEKIQ_CONCURRENCY=5
 
 APEX_FTP_ENABLED="false"

config/initializers/sidekiq.rb

@@ -1,10 +1,6 @@
-# YAML is part of the Ruby standard library and it is used here to convert
-# "['server1', 'server2', 'server3']" into ['server1', 'server2', 'server3']
-require 'yaml'
-sentinels = YAML::load(ENV['REDIS_SENTINELS'])
 Sidekiq.configure_server do |config|
-  if sentinels.present?
-    sentinel_list = sentinels.map do |sentinel_host|
+  if TahiEnv.redis_sentinel_enabled?
+    sentinel_list = TahiEnv.redis_sentinels.map do |sentinel_host|
       { host: sentinel_host, port: ENV['REDIS_PORT'] }
     end
     config.redis = {
@@ -33,8 +29,8 @@
 end
 
 Sidekiq.configure_client do |config|
-  if sentinels.present?
-    sentinel_list = sentinels.map do |sentinel_host|
+  if TahiEnv.redis_sentinel_enabled?
+    sentinel_list = TahiEnv.redis_sentinels.map do |sentinel_host|
       { host: sentinel_host, port: ENV['REDIS_PORT'] }
     end
     config.redis = {

lib/tahi_env.rb

@@ -4,6 +4,7 @@
 require File.dirname(__FILE__) + '/tahi_env/env_var'
 require File.dirname(__FILE__) + '/tahi_env/optional_env_var'
 require File.dirname(__FILE__) + '/tahi_env/required_env_var'
+require File.dirname(__FILE__) + '/tahi_env/array_validator'
 require File.dirname(__FILE__) + '/tahi_env/boolean_validator'
 require File.dirname(__FILE__) + '/tahi_env/presence_validator'
 
@@ -34,7 +35,7 @@ def self.validate!
   #     TahiEnv.APP_NAME # returns the raw env variable
   #     TahiEnv.app_name # returns the coerced env variable value
   #
-  # The second form above makes more sense when accesing booleans:
+  # The second form above makes more sense when accessing booleans:
   #
   #     required :FOO_ENABLED, :boolean
   #
@@ -149,7 +150,8 @@ def self.validate!
   required :PUSHER_VERBOSE_LOGGING, :boolean
 
   # Redis
-  optional :REDIS_SENTINELS
+  optional :REDIS_SENTINEL_ENABLED, :boolean, default: false
+  required :REDIS_SENTINELS, :array, default: [], if: :redis_sentinel_enabled?
 
   # Salesforce
   optional :SALESFORCE_ENABLED, :boolean, default: true

lib/tahi_env/array_validator.rb

@@ -0,0 +1,17 @@
+require File.dirname(__FILE__) + '/../tahi_env'
+
+class TahiEnv
+  class ArrayValidator < ActiveModel::EachValidator
+    def validate_each(record, attribute, value)
+      if value
+        unless YAML::load(value).kind_of?(Array)
+          message = options[:message] || "Environment Variable: #{attribute} was expected to be set to a string that contains an array of strings, but was set to #{value.inspect}. Allowed array value is in the format \"['server1', 'server2' ,'server3']\"."
+          record.errors.add :base, message
+        end
+      else
+        message = options[:message] || "Environment Variable: #{attribute} was expected to be set to a string that contains an array of strings, but was not set. Allowed array value is in the format \"['server1', 'server2' ,'server3']\"."
+        record.errors.add :base, message
+      end
+    end
+  end
+end

lib/tahi_env/dsl_methods.rb

@@ -50,7 +50,13 @@ def required(key, *args)
       )
       register_env_var(required_env_var)
 
-      validation_args = required_env_var.boolean? ? { boolean: true } : { presence: true }
+      validation_args = if required_env_var.boolean?
+                          { boolean: true }
+                        elsif required_env_var.array?
+                          { array: true }
+                        else
+                          { presence: true }
+                        end
 
       validation_args[:if] = if_method if if_method
       validates key, **validation_args

lib/tahi_env/env_var.rb

@@ -21,6 +21,8 @@ def value
         default_value
       elsif boolean?
         converted_boolean_value
+      elsif array?
+        converted_array_value
       else
         raw_value_from_env
       end
@@ -30,6 +32,10 @@ def raw_value_from_env
       ENV[@key]
     end
 
+    def array?
+      @type == :array
+    end
+
     def boolean?
       @type == :boolean
     end
@@ -42,6 +48,12 @@ def to_s
 
     private
 
+    def converted_array_value
+      # This is used to convert a string that contains
+      # an array into a Ruby array object
+      YAML::load(raw_value_from_env)
+    end
+
     def converted_boolean_value
       ['true', '1'].include?(raw_value_from_env.downcase)
     end