Configuring OmniAuth does not prevent standard GitLab authentication or LDAP (if configured) from continuing to work. Users can choose to sign in using any of the configured mechanisms.
- [OmniAuth configuration sample when using Omnibus GitLab](https://gitlab.com/gitlab-org/omnibus-gitlab/tree/master#omniauth-google-twitter-github-login)
Existing users can enable OmniAuth for specific providers after the account is created. For example, if the user originally signed in with LDAP an OmniAuth provider such as Twitter can be enabled. Follow the steps below to enable an OmniAuth provider for an existing user.
1. Sign in normally - whether standard sign in, LDAP, or another OmniAuth provider.
1. Go to profile settings (the silhouette icon in the top right corner).
GitLab uses [Omniauth](http://www.omniauth.org/) for authentication and already ships with a few providers preinstalled (e.g. LDAP, GitHub, Twitter). But sometimes that is not enough and you need to integrate with other authentication solutions. For these cases you can use the Omniauth provider.
### Steps
These steps are fairly general and you will need to figure out the exact details from the Omniauth provider's documentation.
- Stop GitLab:
sudo service gitlab stop
- Add the gem to your [Gemfile](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/Gemfile):
gem "omniauth-your-auth-provider"
- If you're using MySQL, install the new Omniauth provider gem by running the following command:
sudo -u git -H bundle install --without development test postgres --path vendor/bundle --no-deployment
- If you're using PostgreSQL, install the new Omniauth provider gem by running the following command:
sudo -u git -H bundle install --without development test mysql --path vendor/bundle --no-deployment
> These are the same commands you used in the [Install Gems section](#install-gems) with `--path vendor/bundle --no-deployment` instead of `--deployment`.
- Start GitLab:
sudo service gitlab start
### Examples
If you have successfully set up a provider that is not shipped with GitLab itself, please let us know.
You can help others by reporting successful configurations and probably share a few insights or provide warnings for common errors or pitfalls by sharing your experience [in the public Wiki](https://github.com/gitlabhq/gitlab-public-wiki/wiki/Custom-omniauth-provider-configurations).
While we can't officially support every possible authentication mechanism out there, we'd like to at least help those with specific needs.