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Bug 2025944 - Compile libguestfs with ./configure --enable-appliance-format-auto to allow for qcow2-format fixed appliances
Summary: Compile libguestfs with ./configure --enable-appliance-format-auto to allow f...
Keywords:
Status: CLOSED ERRATA
Alias: None
Product: Red Hat Enterprise Linux 9
Classification: Red Hat
Component: libguestfs
Version: 9.0
Hardware: Unspecified
OS: Unspecified
unspecified
unspecified
Target Milestone: rc
: ---
Assignee: Virtualization Maintenance
QA Contact: YongkuiGuo
URL:
Whiteboard:
: 2024152 (view as bug list)
Depends On: 1967166
Blocks:
TreeView+ depends on / blocked
 
Reported: 2021-11-23 12:55 UTC by Richard W.M. Jones
Modified: 2022-05-17 12:38 UTC (History)
8 users (show)

Fixed In Version: libguestfs-1.46.0-5.el9
Doc Type: If docs needed, set a value
Doc Text:
Clone Of: 1967166
Environment:
Last Closed: 2022-05-17 12:28:38 UTC
Type: Bug
Target Upstream Version:
Embargoed:

Attachments (Terms of Use)


Links
System ID Private Priority Status Summary Last Updated
Red Hat Issue Tracker RHELPLAN-103663 0 None None None 2021-11-23 12:56:37 UTC
Red Hat Product Errata RHBA-2022:2317 0 None None None 2022-05-17 12:28:58 UTC

Description Richard W.M. Jones 2021-11-23 12:55:00 UTC 
+++ This bug was initially created as a clone of Bug #1967166 +++

Description of problem:
Kubevirt plans to integrate libguestfs. The build setup uses bazel to build the container images, and this requires a fixed appliance. The appliance is extracted and copy into the container image layer. The root filesystem is a sparse file, and it makes the image size very large 5.59GB. A better option would be to use qcow2 format for the root. However, the current libguestfs explicitly set raw for the root. It will be very useful to have a way to be able to use qcow2 format for the root filesystem 


Version-Release number of selected component (if applicable):
libguestfs 1.44


How reproducible:
Always

Steps to Reproduce:
1. Extract the libguestfs appliance 
2. Build a container image with the extracted appliance
3. Verify the image size

Additional info:
The original problem can be found at https://github.com/kubevirt/kubevirt/pull/5402

--- Additional comment from Richard W.M. Jones on 2021-06-03 09:30:48 UTC ---

The request here is to use the build option:

  ./configure --enable-appliance-format-auto

This changes the way libguestfs opens the appliance by not forcing the
root disk to be in raw format.  The exact changes are:

https://github.com/libguestfs/libguestfs/blob/e68a844eb406f0b32cc2c4e60ca66bc1a7f94bdc/lib/launch-direct.c#L641

https://github.com/libguestfs/libguestfs/blob/e68a844eb406f0b32cc2c4e60ca66bc1a7f94bdc/lib/launch-libvirt.c#L497

Because we don't force raw format, this makes it possible to construct
a qcow2-based fixed appliance, which works around the problems that
containers have preserving sparseness.  For libguestfs in Fedora we
will of course continue to use a supermin-built appliance in raw format.

I wanted to see if this would have any overhead on the ordinary (raw) case.
On my own system, without the option:

$ ./run hyperfine -w 3 'guestfish -a /dev/null run'
Benchmark #1: guestfish -a /dev/null run
  Time (mean ± σ):      1.601 s ±  0.015 s    [User: 18.3 ms, System: 19.6 ms]
  Range (min … max):    1.580 s …  1.625 s    10 runs

With the option:

$ ./run hyperfine -w 3 'guestfish -a /dev/null run'
Benchmark #1: guestfish -a /dev/null run
  Time (mean ± σ):      1.596 s ±  0.023 s    [User: 16.5 ms, System: 21.3 ms]
  Range (min … max):    1.570 s …  1.647 s    10 runs

This is well within error bars so I'm not worried from that point of view.
Comment 1 Richard W.M. Jones 2021-11-23 12:55:34 UTC 
*** Bug 2024152 has been marked as a duplicate of this bug. ***
Comment 2 Richard W.M. Jones 2021-11-23 12:59:36 UTC 
Reproducer:

$ cd /var/tmp
$ libguestfs-make-fixed-appliance appliance
$ ls -l appliance
total 304916
-rw-r--r--. 1 rjones rjones    6039040 Nov 23 12:32 initrd
-rwxr-xr-x. 1 rjones rjones   10971128 Nov 23 12:32 kernel
-rw-r--r--. 1 rjones rjones        978 Nov 23 12:32 README.fixed
-rw-r--r--. 1 rjones rjones 4294967296 Nov 23 12:32 root

The following command should work (as it's using the raw-format root appliance).
This is not the reproducer, just a sanity check that libguestfs + appliance is working:

$ LIBGUESTFS_PATH=$PWD/appliance libguestfs-test-tool

The following commands convert the root appliance to qcow2 format and repeat the test:

$ qemu-img convert -f raw appliance/root.raw -O qcow2 appliance/root
$ file appliance/root
appliance/root: QEMU QCOW2 Image (v3), 4294967296 bytes

$ LIBGUESTFS_PATH=$PWD/appliance libguestfs-test-tool

That command will fail when trying to mount the root filesystem, just after
loading modules.
Comment 5 YongkuiGuo 2021-11-24 04:09:06 UTC 
Verified with package:
libguestfs-1.46.0-5.el9.x86_64

Steps:

1. On rhel9 host
$ cd /var/tmp
$ libguestfs-make-fixed-appliance appliance
$ ls -l appliance
total 305836
-rw-r--r--. 1 yoguo yoguo    6039040 Nov 23 22:59 initrd
-rwxr-xr-x. 1 yoguo yoguo   10972216 Nov 23 22:59 kernel
-rw-rw-r--. 1 yoguo yoguo        978 Nov 23 22:59 README.fixed
-rw-r--r--. 1 yoguo yoguo 4294967296 Nov 23 22:59 root

$ LIBGUESTFS_PATH=$PWD/appliance libguestfs-test-tool
...
===== TEST FINISHED OK =====

$ mv appliance/root  appliance/root.raw
$ qemu-img convert -f raw appliance/root.raw -O qcow2 appliance/root
$ file appliance/root
appliance/root: QEMU QCOW2 Image (v3), 4294967296 bytes
$ LIBGUESTFS_PATH=$PWD/appliance libguestfs-test-tool
...
libguestfs: command: run: qemu-img
libguestfs: command: run: \ info
libguestfs: command: run: \ -U
libguestfs: command: run: \ --output json
libguestfs: command: run: \ /var/tmp/appliance/root
libguestfs: parse_json: qemu-img info JSON output:\n{\n    "virtual-size": 4294967296,\n    "filename": "/var/tmp/appliance/root",\n    "cluster-size": 65536,\n    "format": "qcow2",\n    "actual-size": 299962368,\n    "format-specific": {\n        "type": "qcow2",\n        "data": {\n            "compat": "1.1",\n            "compression-type": "zlib",\n            "lazy-refcounts": false,\n            "refcount-bits": 16,\n            "corrupt": false,\n            "extended-l2": false\n        }\n    },\n    "dirty-flag": false\n}\n\n
libguestfs: command: run: qemu-img
libguestfs: command: run: \ create
libguestfs: command: run: \ -f qcow2
libguestfs: command: run: \ -o backing_file=/var/tmp/appliance/root,backing_fmt=qcow2
libguestfs: command: run: \ /tmp/libguestfsJQ1mE2/overlay2.qcow2
Formatting '/tmp/libguestfsJQ1mE2/overlay2.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=4294967296 backing_file=/var/tmp/appliance/root backing_fmt=qcow2 lazy_refcounts=off refcount_bits=16
...
===== TEST FINISHED OK =====
Comment 8 errata-xmlrpc 2022-05-17 12:28:38 UTC 
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory (new packages: libguestfs), and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHBA-2022:2317
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