You can customize Fider (e.g use OAuth with GitHub) by editing `__INSTALL_DIR__/custom_fider_env` (you might have to create it).
Don't forget to *export* the variables in this file, just like in a bash script:

export OAUTH_GITHUB_SECRET=[your github secret]
export OAUTH_GITHUB_CLIENTID=[your github client id]

You'll find the documentation here for OAuth: <https://fider.io/docs/configuring-oauth>.