Gitlab CI secret - binary file

Is it possible to add binary file as variable to gitlab ci?

You can use CI variables. So you can passed Masked credentials

Can you explain please?
I see in my Gitlab UI possibility to add either secret string or secret file, whose content I should add to a text area. No possibility to upload a file

This option was not available for a long time, but according to GitLab Docs, this option was made publicly available in GitLab version 15.7.

It should be available under Settings > CI/CD > Secure Files in your project.

You can read more about it in the official post here.