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Manage firecracker images in usr not var #75

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87ee356
Manage firecracker images in usr not var
schaefi Apr 9, 2026
267f2aa
fix preserving data
schaefi Apr 14, 2026
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10 changes: 5 additions & 5 deletions doc/firecracker-pilot.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -95,13 +95,13 @@ can be set for the firecracker engine:
overlay_size: 20GiB

# Path to rootfs image done by app registration
rootfs_image_path: /var/lib/firecracker/images/NAME/rootfs
rootfs_image_path: /usr/share/firecracker/images/NAME/rootfs

# Path to kernel image done by app registration
kernel_image_path: /var/lib/firecracker/images/NAME/kernel
kernel_image_path: /usr/share/firecracker/images/NAME/kernel

# Optional path to initrd image done by app registration
initrd_path: /var/lib/firecracker/images/NAME/initrd
initrd_path: /usr/share/firecracker/images/NAME/initrd

After reading of the app configuration information the application
will be called using the configured engine. If no runtime
Expand Down Expand Up @@ -166,8 +166,8 @@ FILES
-----

* /usr/share/flakes
* /var/lib/firecracker/images
* /var/lib/firecracker/storage
* /usr/share/firecracker/images
* /usr/share/firecracker/storage
* /etc/flakes

AUTHOR
Expand Down
6 changes: 3 additions & 3 deletions doc/flake-ctl-firecracker-pull.rst
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Expand Up @@ -26,18 +26,18 @@ DESCRIPTION
-----------

Pull the components of a firecracker image from the given location
into `/var/lib/firecracker/images/NAME` on the local machine.
into `/usr/share/firecracker/images/NAME` on the local machine.
After completion the available firecracker images can be listed via:

.. code:: bash

$ tree /var/lib/firecracker/images
$ tree /usr/share/firecracker/images

and shows a file structure like in the following example

.. code:: bash

/var/lib/firecracker/images
/usr/share/firecracker/images
└── myImage
├── initrd
├── kernel
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4 changes: 2 additions & 2 deletions doc/flake-ctl-firecracker-remove.rst
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Expand Up @@ -44,13 +44,13 @@ OPTIONS

--vm <VM>

VM basename as provided via **ls -1 /var/lib/firecracker/images**
VM basename as provided via **ls -1 /usr/share/firecracker/images**

FILES
-----

* /usr/share/flakes
* /var/lib/firecracker/images
* /usr/share/firecracker/images

EXAMPLE
-------
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2 changes: 1 addition & 1 deletion firecracker-pilot/src/defaults.rs
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Expand Up @@ -35,7 +35,7 @@ pub const OVERLAY_UPPER: &str =
pub const OVERLAY_WORK: &str =
"overlayroot/rootfs_work";
pub const FIRECRACKER_OVERLAY_DIR:&str =
"/var/lib/firecracker/storage";
"/usr/share/firecracker/storage";
pub const FIRECRACKER_TEMPLATE:&str =
"/etc/flakes/firecracker.json";
pub const FIRECRACKER_VSOCK_PREFIX: &str =
Expand Down
6 changes: 3 additions & 3 deletions firecracker-pilot/src/firecracker.rs
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Expand Up @@ -155,13 +155,13 @@ pub fn create(program_name: &String) -> Result<(String, String), FlakeError> {
overlay_size: 20g

# Path to rootfs image done by app registration
rootfs_image_path: /var/lib/firecracker/images/NAME/rootfs
rootfs_image_path: /usr/share/firecracker/images/NAME/rootfs

# Path to kernel image done by app registration
kernel_image_path: /var/lib/firecracker/images/NAME/kernel
kernel_image_path: /usr/share/firecracker/images/NAME/kernel

# Optional path to initrd image done by app registration
initrd_path: /var/lib/firecracker/images/NAME/initrd
initrd_path: /usr/share/firecracker/images/NAME/initrd

include:
tar:
Expand Down
4 changes: 2 additions & 2 deletions flake-ctl/src/defaults.rs
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Expand Up @@ -33,9 +33,9 @@ pub const FLAKE_TEMPLATE_CONTAINER:&str =
pub const FLAKE_TEMPLATE_FIRECRACKER:&str =
"/etc/flakes/firecracker-flake.yaml";
pub const FIRECRACKER_REGISTRY_DIR:&str =
"/var/lib/firecracker";
"/usr/share/firecracker";
pub const FIRECRACKER_IMAGES_DIR:&str =
"/var/lib/firecracker/images";
"/usr/share/firecracker/images";
pub const FIRECRACKER_INITRD_NAME:&str =
"initrd";
pub const FIRECRACKER_KERNEL_NAME:&str =
Expand Down
16 changes: 11 additions & 5 deletions package/flake-pilot.spec
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Expand Up @@ -141,9 +141,9 @@ make DESTDIR=%{buildroot}/ install_sci
mkdir -p %{buildroot}/overlayroot
mkdir -p %{buildroot}/usr/lib/flake-pilot

mkdir -p %{buildroot}/var/lib/firecracker/images
mkdir -p %{buildroot}/usr/share/firecracker/images

mkdir -p %{buildroot}/var/lib/firecracker/storage
mkdir -p %{buildroot}/usr/share/firecracker/storage

mkdir -p %{buildroot}/etc/dracut.conf.d
mkdir -p %{buildroot}/usr/lib/dracut/modules.d/80netstart
Expand Down Expand Up @@ -180,9 +180,9 @@ install -m 644 flakes.yml %{buildroot}/etc/flakes.yml
%doc /usr/share/man/man8/podman-pilot.8.gz

%files -n flake-pilot-firecracker
%dir /var/lib/firecracker
%dir /var/lib/firecracker/images
%dir /var/lib/firecracker/storage
%dir /usr/share/firecracker
%dir /usr/share/firecracker/images
%dir /usr/share/firecracker/storage
%dir /usr/lib/flake-pilot
%config /etc/flakes/firecracker-flake.yaml
%config /etc/flakes/firecracker.json
Expand All @@ -193,6 +193,12 @@ install -m 644 flakes.yml %{buildroot}/etc/flakes.yml
%doc /usr/share/man/man8/firecracker-pilot.8.gz
/usr/lib/flake-pilot/sci

%post -n flake-pilot-firecracker
if [ "$YAST_IS_RUNNING" != "instsys" ] && [ -d /var/lib/firecracker ];then
rsync -za /var/lib/firecracker/ /usr/share/firecracker/
rm -rf /var/lib/firecracker
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@rjschwei rjschwei Apr 14, 2026

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I think this might trigger an RPM error on package upgrade. RPM will try to remove any files that are not part of the new package on it's own. Since the new package no longer owns /var/lib/firecracker RPM will try to remove this directory, but it will already be gone due to the %post action. I am not sure if RPM ignores that error or complains.

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@schaefi schaefi Apr 14, 2026

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it's worse. I talked to some rpm experts. Here is the answer

you need to keep the old directory in the filelist or rpm will delete it on transaction which breaks your post script

I added a commit to address this situation

@rjschwei now the question is, if I have to keep the old location as a %dir in order to allow the move, does that break the idea of SUSE's immutable system concept ?

Thanks

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@rjschwei rjschwei Apr 14, 2026

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Sorry, when I reviewed this I completely lost track of the context as to why these changes are being made, my bad. There should actually not be any moving. On a transactional-update system /usr is immutable, meaning with the current code if a user actually wants to add a firecracker image that operation would fail. The location where the images are store has to remain the same, i.e. /var/lib/firecracker.

What you need to do is create flake-pilot.conf file which contains

d /var/lib/firecracker
d /var/lib/firecracker/images
d /var/lib/firecracker/storage

and then in the spec file own those directories as %ghost.

Sorry for not picking up on this on the first review.

fi

%files -n flake-pilot-firecracker-dracut-netstart
%dir /usr/lib/dracut
%dir /usr/lib/dracut/modules.d
Expand Down
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