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Tested okey dokey on:

- Debian 12.7.0 Gnome amd64
- Ubuntu 24.04.1 LTS amd64
- Linux Mint Cinnamon 22 amd64

Were you able to do anything regarding alpine linux?  I looked at the packages involved and it is the "live-boot and live-config" packages that are missing and I don't know what could be used to replace their function - if this is possible.

The refracta-tools scripts have spoiled me.

Problem:
"Compression error for type [cpio archive]" when extracting initrd.img-6.5.0-26-generic.

Investigation:
1. [xed /var/log/refractasnapshot.log]:

Replace "xed" with your favorite editor.

++ file -L /boot/initrd.img-6.5.0-26-generic
++ egrep -o 'Zstandard compressed|gzip compressed|XZ compressed|cpio archive'
+ initrd_compression='cpio archive'
+ '[' '!' 'cpio archive' ']'
+ popd
+ '[' 'cpio archive' == 'Zstandard compressed' ']'
+ '[' 'cpio archive' == 'gzip compressed' ']'
+ '[' 'cpio archive' == 'XZ compressed' ']'
+ popd
+ echo 'Initrd is extracted'
+ edit_initrd
+ pushd /tmp/extracted
+ '[' -f conf/conf.d/cryptroot ']'
+ '[' -f cryptroot/crypttab ']'
+ '[' -f conf/conf.d/resume ']'
+ '[' -f conf/conf.d/zz-resume-auto ']'
+ popd
+ rebuild_initrd
+ pushd /tmp/extracted
+ '[' 'cpio archive' == 'gzip compressed' ']'
+ '[' 'cpio archive' == 'XZ compressed' ']'
+ '[' 'cpio archive' == 'Zstandard compressed' ']'
+ echo 'Compression error for type [cpio archive]...'
+ exit 1

2. The command [file -L /boot/initrd.img-6.5.0-26-generic] returns "ASCII cpio archive (SVR4 with no CRC)". This information is flaw.

Cause:
Linux Mint 21.3 uses an initrd.img file of type "initramfs" as of kernel version 5.15.0-94, and cannot be extracted/rebuilded using the cpio command.

Solution:
Use unmkinitramfs to extract- and mkinitramfs to rebuild the initrd file.

(tested on kernel: vmlinuz-6.5.0-26-generic, initrd: initrd.img-6.5.0-26-generic, distro: Linux Mint 21.3, desktop: Cinnamon 6.0.4, base: Ubuntu 22.04)

> [sudo xed /bin/refractasnapshot-gui]
> search for: "extract_initrd ()"

> replace:
from: extract_initrd () {
to:    }
with:

extract_initrd () {
# Customized {FillInCurrentDateTime} by {FillInYourName} 

    rm -rf /tmp/extracted
    mkdir /tmp/extracted
    pushd /tmp/extracted	
    
    unmkinitramfs "$initrd_image" "/tmp/extracted"
    
    if [ $? -eq 0 ]; then 
        echo "SUCCESS: unmkinitramfs has successfully extracted the original Initrd to /tmp/extracted" 
    else 
        echo "ERROR: unmkinitramfs has failed to extract the original Initrd"
        echo "Script execution terminated"
        rm -rf /tmp/extracted
        exit 1 
    fi
    popd
}

> search for: "rebuild_initrd ()"

> replace:
from: rebuild_initrd () {
to:    }
with:

rebuild_initrd () {
# Customized {FillInCurrentDateTime} by {FillInYourName}

    pushd /tmp/extracted
    mkinitramfs -c gzip -o ${work_dir}/iso/live/${initrd_image##*/}

    if [ $? -eq 0 ]; then 
        echo "SUCCESS: mkinitramfs has successfully rebuilded the custom Initrd" 
    else 
        echo "ERROR: mkinitramfs has failed to rebuild the custom Initrd"
        echo "Script execution terminated"
        rm -rf /tmp/extracted
        exit 1 
    fi
    popd
    rm -rf /tmp/extracted
}

Notice that the container is compressed using the gzip algorithm. I guess this solution can also help Ubuntu users.

Nonetheless, still very happy using Refracta Snapshot!

@pcalvert: The refracta tools rely on live-boot and live-config, which are debian-based packages. You might need to cobble some stuff into place manually to get it to work. Look at the other dependencies to see if alpine uses the same package names. (Does alpine use apt?)

And, I see: In Ubuntu 16 LTS for AMD64, there is no «live-config-upstart»

from apt-search live-config:

but it seems to be difficult to find a ".deb" for Ubuntu 2016 LTS AMD64.

And I will be prudent using other: I did have A LOT of successles experiment in the last times with live-config ending with errors no reparable.

If it's a really old ubuntu, replace live-config-systemd with live-config-upstart.

I don't know why that 'zcat' is there when initrd is uncompressed.

Which kernel/OS are you running?

https://linuxconfig.org/how-to-uncompre … t-on-linux

Thanks for posting this.

(cpio -i ; zcat | cpio -i) < "$initrd_image"

to this:

cpio -i < "$initrd_image"

succeeds.

I don't know why that 'zcat' is there when initrd is uncompressed.

Long story short I could not get around the compression problem with Ubuntu....
So, with Ubuntu what we did was take the "Snapshot without" crypt-setup, and then later  I used  a tool called "Cubic" to update the ISO.
https://launchpad.net/cubic
And that was problem solved.

But....I am glad I came here, because the work you guys have done and the  freedom you offer speaks volumes. 
I think a lot of folks just don't understand just how much systemd touches so many things... 

Who knows maybe I can convince my community, and team to be open to a Devuan base  
I hear OpenRc may be the init to use though....is that true I am really ignorant on that subject..?

Again.... thank you!

Note 1: I chose gzip because the command was easier to type than xz, and I did not attempt to figure out the correct lz4 command. I just wanted to make sure the microcode didn't get lost.

Note 2: Since it was a live session, there were only dead symlinks in /boot, so I used /cdrom/casper/initrd for the extraction.

Here are my results,
**I have not tried the manual method @fsmithred mentioned yet.

I did change the compression in the initramfs.conf to gzip and updated the initramfs no issues there...
Ran Snapshot and it ...came back with the same Decompression error.

Now....for myself I know exactly where the  problem area is in the snapshot script. That is here which is what you guys have already mentioned.

	elif [ "$COMPRESSION" = "cpio archive" ]; then
		echo "Archive is cpio archive..."
		(cpio -i ; zcat | cpio -i) < "$initrd_image"
		exit_code="$?"
		if [ "$exit_code" -ne 0 ] ; then
			(cpio -i ; xzcat | cpio -i) < "$initrd_image"
			exit_code="$?"
			if [ "$exit_code" -ne 0 ] ; then
				echo "Decompression error" && exit 1

Before I try the  manual method I wanted to ask the following:
Ubuntu talks about using unmkinitramfs to extract an  initramfs image.... because they are using lz4
The manpage is here: https://manpages.debian.org/buster/init … .8.en.html
Starting with 20.04...... lz4 is the standard used by Ubuntu to compress an initramfs image.

My question is......is unmkinitramfs the correct tool that I should try to add to the snapshot script?
or.... am I going in the wrong direction