added OAUTH_AUTO_LINK_USER option

Author: Rene Gärtner

README.md

@@ -1021,6 +1021,7 @@ Below is the complete list of available options that can be used to customize yo
 | `OAUTH_BLOCK_AUTO_CREATED_USERS` | Locks down those users until they have been cleared by the admin. Defaults to `true`. |
 | `OAUTH_AUTO_LINK_LDAP_USER` | Look up new users in LDAP servers. If a match is found (same uid), automatically link the omniauth identity with the LDAP account. Defaults to `false`. |
 | `OAUTH_AUTO_LINK_SAML_USER` | Allow users with existing accounts to login and auto link their account via SAML login, without having to do a manual login first and manually add SAML. Defaults to `false`. |
+| `OAUTH_AUTO_LINK_USER` | Allow users with existing accounts to login and auto link their account via the defined Omniauth providers login, without having to do a manual login first and manually connect their chosen provider. Defaults to `[]`. |
 | `OAUTH_EXTERNAL_PROVIDERS` | Comma separated list if oauth providers to disallow access to `internal` projects. Users creating accounts via these providers will have access internal projects. Accepted values are `cas3`, `github`, `bitbucket`, `gitlab`, `google_oauth2`, `facebook`, `twitter`, `saml`, `crowd`, `auth0` and `azure_oauth2`. No default. |
 | `OAUTH_CAS3_LABEL` | The "Sign in with" button label. Defaults to "cas3". |
 | `OAUTH_CAS3_SERVER` | CAS3 server URL. No defaults. |

assets/runtime/config/gitlabhq/gitlab.yml

@@ -883,6 +883,12 @@ production: &base
     # (default: false)
     auto_link_saml_user: {{OAUTH_AUTO_LINK_SAML_USER}}
 
+    # Allow users with existing accounts to login and auto link their account via the
+    # defined Omniauth providers login, without having to do a manual login first and
+    # manually connect their chosen provider.
+    # (default: [])
+    auto_link_user: [{{OAUTH_AUTO_LINK_USER}}]
+
     # Set different Omniauth providers as external so that all users creating accounts
     # via these providers will not be able to have access to internal projects. You
     # will need to use the full name of the provider, like `google_oauth2` for Google.

assets/runtime/functions

@@ -699,6 +699,7 @@ gitlab_configure_oauth() {
     OAUTH_BLOCK_AUTO_CREATED_USERS \
     OAUTH_AUTO_LINK_LDAP_USER \
     OAUTH_AUTO_LINK_SAML_USER \
+    OAUTH_AUTO_LINK_USER \
     OAUTH_EXTERNAL_PROVIDERS
 
   case ${OAUTH_AUTO_SIGN_IN_WITH_PROVIDER} in