Images built FROM runenv cannot use Dockerfile RUN

[msterin]

Since Docker build does not accept --device or --volume flags, we cannot use RUN in dockerfiles where FROM uses any of Kontain runenv images. This makes Kontainer building supercumbersome

Capturing the issue for discussion //CC @gnode1

As one of the suggestions for discussions, we may just link all for -alpine instead of linking with Kontain runtime. This way the resulting Kontainer will be fully functional in both (km and non-km) worlds. Though we need to think about security implications (e.g. do we expand atttack surface) more, so for now just capturing the point.

[msterin]

We can live with this for a while, with the following guidance to customers (and us)

• 2 stage in Dockerfile
• 1st builds original customer container, then packs all app files into a tarball\
• 2d stage does FROM runenv and ADDs file from the tarball (alternative: just multiple COPY , and then stage is unmodified)

[gnode1]

Actually some limited collection of RUN works. And this limitation is consequence of our design.

For now there are some examples (springboot, tensorflow) of busybox based containers. The flow there is two staged dockerfile, with the last stage (the one built on busybox) only doing ADD or COPY. For now this is going to be plan of records, we'll see how it flies. Moving this to know issues.