Not Able To Access Environment Variable In Custom Theme


I am Passing Environment Variable Through docker yml file ss given below

And Using in custom theme info.ftl like this ${env.CUSTOM_BACK_TO_LOGIN_URL}

By Referring this link Server Developer Guide
but i am getting error

Is this right way to use environment variables ? Or If You Have Any documents please share
Thanking You

I might be late here, but it might be useful for someone having same issue

We cannot directly access env variables inside ftl theme templates, we can access them in theme properties like below


and then refer the property value in theme ftl files as below