Below is the text of the LDAP section of my gitlab.rb file (minus identifying information). Despite having this all configured, LDAP as an authentication method will not enable. It does not show up as enabled in the admin console and when I perform a

sudo gitlab-rake gitlab:ldap:check

it returns

LDAP: ... LDAP is disabled in config/gitlab.yml

a file that does not exist as my understanding of the TurnKey is that it's an Omnibus installation, not a source.

gitlab_rails['ldap_enabled'] = true
gitlab_rails['prevent_ldap_sign_in'] = false
gitlab_rails['ldap_servers'] = YAML.load <<-'EOS'
main: # 'main' is the GitLab 'provider ID' of this LDAP server
  label: 'LDAP'
  host: 'tf-dc1.placeholder.local'
  port: 389
  uid: 'sAMAccountName'
  bind_dn: 'CN=LDAPAuth,OU=IT,OU=placeholder,DC=placeholder,DC=local'
  password: 'placeholder'
  encryption: 'plain' # "start_tls" or "simple_tls" or "plain"
  verify_certificates: true
  smartcard_auth: false
  active_directory: true
  allow_username_or_email_login: false
  lowercase_usernames: false
  block_auto_created_users: false
  base: 'DC=placeholder,DC=local'
EOS

Also attempted with a more traditional YAML formatting.

gitlab_rails['ldap_enabled'] = true
gitlab_rails['prevent_ldap_sign_in'] = false
gitlab_rails['ldap_servers'] = {
'main' => {
  'label' => 'LDAP',
  'host' => 'tf-dc1.placeholder.local',
  'port' => 389,
  'uid' => 'sAMAccountName',
  'encryption' => 'simple_tls',
  'verify_certificates' => true,
  'bind_dn' => 'CN=LDAPAuth,OU=IT,OU=placeholder,DC=placeholder,DC=local',
  'password' => 'placeholder',
  'encryption' => 'plain',
  'verify_certificates' => true,
  'tls_options' => {
  'ca_file' => '',
  'ssl_version' => '',
  'ciphers' => '',
  'cert' => '',
  'key' => ''
  },
  'timeout' => 10,
  'active_directory' => true,
  'allow_username_or_email_login' => false,
  'block_auto_created_users' => false,
  'base' => 'dc=placeholder,dc=local',
  'user_filter' => '',
  'attributes' => {
    'username' => ['uid', 'userid', 'sAMAccountName'],
    'email' => ['mail', 'email', 'userPrincipalName'],
    'name' => 'cn',
    'first_name' => 'givenName',
    'last_name' => 'sn'
  },
  'lowercase_usernames' => false,

  #EE Only

  'group_base' => '',
  'admin_group' => '',
  'external_groups' => [],
  'sync_ssh_keys' => false
  }

}