WIP: overlay: Don't mount /boot/efi by default

[cgwalters]

Nothing in the OS touches the ESP by default, so there's
no reason to mount it by default, particularly writable.
This is good for avoiding wear&tear on the filesystem, but
I am specifically doing this as preparation for potentially
removing the ESP from AWS images, because AWS ImportImage
chokes on its presence:
openshift/os#396

[jlebon]

I am specifically doing this as preparation for potentially
removing the ESP from AWS images, because AWS ImportImage
chokes on its presence:

Yeah... I was looking into the RHBZ behind this this morning. We're probably going to have to do this. :(

Hmm, if we do do this, I wonder if it'd work to instead just put the symlink in $UNIT_DIR/dev-disk-by\x2dlabel-EFI\x2dSYSTEM.device.wants/? That way, we still mount it on platforms that have it. (Not against just not mounting it outright, though I do like the symmetry.)

[cgwalters]

Hmm, if we do do this, I wonder if it'd work to instead just put the symlink in $UNIT_DIR/dev-disk-by\x2dlabel-EFI\x2dSYSTEM.device.wants/?

Err...that's backwards right? I guess it'd work because actually in systemd Wants= is distinct from After= but...

For now I pushed some code to just not mount on aws but I need to actually test this.

[jlebon]

I guess it'd work because actually in systemd Wants= is distinct from After= but...

Right, it's just about pulling the unit into the transaction.

Making it conditional on ignition.platform.id WFM though it seems nicer to just automatically mount it if we find the partition. There's probably a cleaner way to do this than the .device.wants hack I suggested above.

[bgilbert]

Should be obsoleted as part of #794.

[bgilbert]

Closing in favor of #794.