[4.0] Offline installer does not handle HTTP URLs in inst.ks kernel parameter

[Muthukumar-Subramaniam]

Azure Linux version
Azure Linux 4.0

Deployment / platform
KVM VM (PXE network boot)

Is your feature request related to a problem? Please describe.
When PXE booting with inst.ks=http://server/path/ks.cfg on the kernel cmdline, the installer wrapper (anaconda-launcher.sh) passes the URL directly to anaconda --text --kickstart="http://server/path/ks.cfg". Anaconda can't fetch URLs when called this way and fails with "Kickstart file ... is missing."
The network is working fine at that point. Curl can download the file from the same shell. The problem is just that anaconda expects a local file path when called as a subprocess.

Describe the solution you'd like
Have anaconda-launcher.sh download the URL to a local file before passing it to anaconda:

if [[ "$CUSTOM_KS" == http* ]]; then
    curl -sf -o /tmp/ks.cfg "$CUSTOM_KS" && CUSTOM_KS="/tmp/ks.cfg"
fi

Describe alternatives you've considered
Patching the squashfs after ISO download to inject this logic. Works but adds complexity to the deployment pipeline.

Additional context
This affects any PXE based deployment that passes a kickstart URL via kernel cmdline. The fix is a few lines in anaconda-launcher.sh.