GitLab OAuth certificate signed by unknown authority

Created by: Antoine98

• Sourcegraph version: 3.5.0
• Platform information: redhat 7.6, Docker version 1.13.1, GitLab Community Edition 11.5.2, Gitlab https certificate with internal authority

Steps to reproduce:

1. Setting Gitlab and sourcegraph Oauth
2. Try to Sign in with GitLab

Actual behavior:

Result is a blanck page with this line of error Post https://gitlab.intranet.xxx/oauth/token: x509: certificate signed by unknown authority

No errors in logs.

Is there a way to configure certificate in management console for gitlab oauth ? (like the option "certificate" in external service , GitLab projects )

Thank you