POC: mount /lib/modules/$(uname...) from a read-only share

[moul]

• Today we have a script that syncs current kernel modules to disk from our mirrors
• The idea is to mount the directory containing the kernel modules on /lib/modules instead of syncing

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Pros:

• /lib/modules is always up to date with the kernel (dynamically mounted based on the current kernel)
• can be done from the initrd, so before every init scripts, so no more hacks on init scripts for the first boot
• save space on user disks
• avoid conserve multiple kernels when switching bootscript often

Cons:

• having a new mountpoint may be disappointing for people
• it may be more difficult to build kernel moduels, we should find a hack as creating a symlink to /usr/src/linux on /lib/modules/${KERNELVERS}/modules/build

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I like this solution and as usual it can be disabled using flags in initrd, so people can use the old method (mirror syncing) if they prefer

[ElNounch]

A PoC using CephFs, mounting a partial mirror of http://mirror.scaleway.com/ on /media/scaleway read-only.
master...ElNounch:PoC_ceph
Act as an helper to scaleway/image-tools#170

[moul]

As said in scaleway/image-tools#170 (comment), thank you, you're awesome!