feature: New block for Docker template

[maxhahn]

Feature request

Right now, I need to add a certificate to my container before any apt-gets can be made. Because there is no templatable block right after the FROM step in the Dockerfile, this is a major hassle.

So, my request is to add a Block right after the FROM step.

Right now, I work around this issue by templating in front of the FROM step, where a base image is defined which can the be loaded as the base image in the bentofile. This is not nice

Motivation

No response

Other

No response

[frostming]

We will soon deliver a new mechanism for customizing the build process, to replace and deprecate the dockerfile template, stay tuned.