[RFC] blueprint: make minsize required for disk.Customizations

[mvo5]

This commit enforces the use of "minsize" for disk customizations. Without this the disk code will create zero sized partitions when minsize is omited which then later yields a strange error from osbuild:

Building manifest-qcow2-raw-vmdk-vhd-gce.json
<stdin> has errors:

.pipelines[1].stages[2].options.volumes[0].size:
  '0B' does not match '[1-9][0-9]*[bBsSkKmMgGtTpPeE]?'

2024/11/25 09:35:42 error: cannot run osbuild: running osbuild failed: exit status 2

We could also attempt to fix this by making guesses about minsize (which is what the existing filesystem customizations do). But that seems less appropriate here as this is about finer control and an arbitrary size of e.g. 1 GiB seems unexpected. Another alternative would be to infere from the parent container size and split equally. But we can always do this later and relax the rules (and even add things like minsize: 50% which would imply the parent container).

[edit: one wart of this is that for partitions with requiedMinsize data this should not be required but at this level we have no way of knowing :(]

[achilleas-k]

We could also attempt to fix this by making guesses about minsize (which is what the existing filesystem customizations do). But that seems less appropriate here as this is about finer control and an arbitrary size of e.g. 1 GiB seems unexpected.

I had the same thought and I agree. I think it makes sense that these "advanced" customizations don't do too much automatically.

You make a good point about the required min sizes. Perhaps we should rethink those too.