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distro/rhel84: use a random uuid for XFS partition

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Imagine this situation: You have a RHEL system booted from an image produced
by osbuild-composer. On this system, you want to use osbuild-composer to
create another image of RHEL.

However, there's currently something funny with partitions:

All RHEL images built by osbuild-composer contain a root xfs partition. The
interesting bit is that they all share the same xfs partition UUID. This might
sound like a good thing for reproducibility but it has a quirk.

The issue appears when osbuild runs the qemu assembler: it needs to mount all
partitions of the future image to copy the OS tree into it.

Imagine that osbuild-composer is running on a system booted from an imaged
produced by osbuild-composer. This means that its root xfs partition has this
uuid:

efe8afea-c0a8-45dc-8e6e-499279f6fa5d

When osbuild-composer builds an image on this system, it runs osbuild that
runs the qemu assembler at some point. As I said previously, it will mount
all partitions of the future image. That means that it will also try to
mount the root xfs partition with this uuid:

efe8afea-c0a8-45dc-8e6e-499279f6fa5d

Do you remember this one? Yeah, it's the same one as before. However, the xfs
kernel driver doesn't like that. It contains a global table[1] of all xfs
partitions that forbids to mount 2 xfs partitions with the same uuid.

I mean... uuids are meant to be unique, right?

This commit changes the way we build RHEL 8.4 images: Each one now has a
unique uuid. It's now literally a unique universally unique identifier. haha

[1]: a349e4c659/fs/xfs/xfs_mount.c (L51)
This commit is contained in:
Ondřej Budai 2020-12-14 22:52:12 +01:00 • committed by Ondřej Budai
parent ae0d1b8663
commit 973639d372
23 changed files with 150 additions and 114 deletions
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6
internal/cloudapi/server.go
View file

@ -5,6 +5,7 @@ package cloudapi
import (
"encoding/json"
"fmt"
"math/rand"
"net/http"
"github.com/go-chi/chi"
@ -81,6 +82,9 @@ func (server *Server) Compose(w http.ResponseWriter, r *http.Request) {
imageRequests := make([]imageRequest, len(request.ImageRequests))
var targets []*target.Target
// use the same seed for all images so we get the same IDs
manifestSeed := rand.Int63()
for i, ir := range request.ImageRequests {
arch, err := distribution.GetArch(ir.Architecture)
if err != nil {
@ -139,7 +143,7 @@ func (server *Server) Compose(w http.ResponseWriter, r *http.Request) {
}
}
manifest, err := imageType.Manifest(nil, imageOptions, repositories, packages, buildPackages)
manifest, err := imageType.Manifest(nil, imageOptions, repositories, packages, buildPackages, manifestSeed)
if err != nil {
http.Error(w, fmt.Sprintf("Failed to get manifest for for %s/%s/%s: %s", ir.ImageType, ir.Architecture, request.Distribution, err), http.StatusBadRequest)
return