Encrypt application setting tokens

This is the plan to encrypt the plaintext tokens:

First release (this commit):
  1. Create new encrypted fields in the database.
  2. Start populating new encrypted fields, read the encrypted fields or
     fallback to the plaintext fields.
  3. Backfill the data removing the plaintext fields to the encrypted fields.

Second release:
  4. Remove the virtual attribute (created in step 2).
  5. Drop plaintext columns from the database (empty columns after step 3).

1 files changed, 41 insertions, 16 deletions

diff --git a/app/models/application_setting.rb b/app/models/application_setting.rb
index a07933d4975..d18f96d82f7 100644
--- a/app/models/application_setting.rb
+++ b/app/models/application_setting.rb
@@ -276,23 +276,24 @@ class ApplicationSetting < ApplicationRecord
                  pass: :external_auth_client_key_pass,
                  if: -> (setting) { setting.external_auth_client_cert.present? }
 
-  attr_encrypted :external_auth_client_key,
-                 mode: :per_attribute_iv,
-                 key: Settings.attr_encrypted_db_key_base_truncated,
-                 algorithm: 'aes-256-gcm',
-                 encode: true
-
-  attr_encrypted :external_auth_client_key_pass,
-                 mode: :per_attribute_iv,
-                 key: Settings.attr_encrypted_db_key_base_truncated,
-                 algorithm: 'aes-256-gcm',
-                 encode: true
+  private_class_method def self.encryption_options_base_truncated_aes_256_gcm
+    {
+      mode: :per_attribute_iv,
+      key: Settings.attr_encrypted_db_key_base_truncated,
+      algorithm: 'aes-256-gcm',
+      encode: true
+    }
+  end
 
-  attr_encrypted :lets_encrypt_private_key,
-                 mode: :per_attribute_iv,
-                 key: Settings.attr_encrypted_db_key_base_truncated,
-                 algorithm: 'aes-256-gcm',
-                 encode: true
+  attr_encrypted :external_auth_client_key, encryption_options_base_truncated_aes_256_gcm
+  attr_encrypted :external_auth_client_key_pass, encryption_options_base_truncated_aes_256_gcm
+  attr_encrypted :lets_encrypt_private_key, encryption_options_base_truncated_aes_256_gcm
+  attr_encrypted :akismet_api_key, encryption_options_base_truncated_aes_256_gcm
+  attr_encrypted :elasticsearch_aws_secret_access_key, encryption_options_base_truncated_aes_256_gcm
+  attr_encrypted :recaptcha_private_key, encryption_options_base_truncated_aes_256_gcm
+  attr_encrypted :recaptcha_site_key, encryption_options_base_truncated_aes_256_gcm
+  attr_encrypted :slack_app_secret, encryption_options_base_truncated_aes_256_gcm
+  attr_encrypted :slack_app_verification_token, encryption_options_base_truncated_aes_256_gcm
 
   before_validation :ensure_uuid!
 
@@ -321,6 +322,30 @@ class ApplicationSetting < ApplicationRecord
     Gitlab::ThreadMemoryCache.cache_backend
   end
 
+  def akismet_api_key
+    decrypt(:akismet_api_key, self[:encrypted_akismet_api_key]) || self[:akismet_api_key]
+  end
+
+  def elasticsearch_aws_secret_access_key
+    decrypt(:elasticsearch_aws_secret_access_key, self[:encrypted_elasticsearch_aws_secret_access_key]) || self[:elasticsearch_aws_secret_access_key]
+  end
+
+  def recaptcha_private_key
+    decrypt(:recaptcha_private_key, self[:encrypted_recaptcha_private_key]) || self[:recaptcha_private_key]
+  end
+
+  def recaptcha_site_key
+    decrypt(:recaptcha_site_key, self[:encrypted_recaptcha_site_key]) || self[:recaptcha_site_key]
+  end
+
+  def slack_app_secret
+    decrypt(:slack_app_secret, self[:encrypted_slack_app_secret]) || self[:slack_app_secret]
+  end
+
+  def slack_app_verification_token
+    decrypt(:slack_app_verification_token, self[:encrypted_slack_app_verification_token]) || self[:slack_app_verification_token]
+  end
+
   def recaptcha_or_login_protection_enabled
     recaptcha_enabled || login_recaptcha_protection_enabled
   end