Can you describe your usage scenario? (That would be helpful)

There are two parts to making the move away from tftp to http. (Might still need tftp to boot iPXE, but can be chainloaded by grub or burned into existing vendor option rom)

Use iPXE to load the kernel and initrd image over http, and secondly to fetch the squashfs using http. The latter requires changes to initrd.gz image. Required changes are shown in the patch below. This includes a change to override the current casper scripts configure_network() to accept ip= as a parameter to the kernel. Examples follows:

• ip=dhcp
• ip=[CLIENT_IP]:[SERVER_IP]:[GATEWAY_IP]:[NETMASK]:[HOSTNAME]:[DEVICE]:[AUTOCONF]
• ip=10.0.0.1::10.0.0.254:255.255.255.0::eth0
• ip=:::::eth1:dhcp

The patch also describe changes to do_netmount() and parse_cmdline() needed to handle NFS, CIFS or the new HTTP booting, and a do_httpmount() to handle the case of HTTP. The casper initrd image does not have a working DNS resolver so NFSROOT= or fetch= have to use IP addresses, iPXE can work around this by resolving the hostname and passing the IP address, but it will not work with virtual http hosting based on hostname.

I "needed" to do this in order to install turnkey linux on a VPS server where I only had root access to running linux and VNC access to the console (no access to dhcp). Adding iPXE to grub and booting into the installer via static ip and http was my best option. If lacking VNC access to the console adding a preseed file to the installer and using grub-reboot might let you replace a headless running linux server with Turnkey.

casper-http-simple.patch

--- initrd/scripts/casper	2016-05-26 11:11:48.505135324 +0200
+++ initrd-patched/scripts/casper	2016-05-31 21:31:30.266314223 +0200
@@ -32,6 +32,10 @@
 parse_cmdline() {
     for x in $(cat /proc/cmdline); do
         case $x in
+            netboot=*)
+                export NETBOOT="${x#netboot=}";;
+            fetch=*)
+                export URL="${x#fetch=}";;
             showmounts|show-cow)
                 export SHOWMOUNTS='Yes' ;;
             persistent)
@@ -191,26 +195,47 @@
     /sbin/udevadm trigger
     /sbin/udevadm settle
 
-    ipconfig ${DEVICE} /tmp/net-${DEVICE}.conf | tee /netboot.config
+	#this seems broken.
+    #ipconfig ${DEVICE} /tmp/net-${DEVICE}.conf | tee /netboot.config
+	#replace with very basic netconfig based on ip= parameter
+	case ${STATICIP} in 
+		dhcp)
+			ipconfig :::::eth0:dhcp
+			;;
+		*)
+			ipconfig ${STATICIP}
+			;;
+	esac
 
     if [ "${NFSROOT}" = "auto" ]; then
         NFSROOT=${ROOTSERVER}:${ROOTPATH}
     fi
 
-    [ "$quiet" != "y" ] && log_begin_msg "Trying netboot from ${NFSROOT}"
-
-    if [ "${NETBOOT}" != "nfs" ] && do_cifsmount ; then
-        rc=0
-    elif do_nfsmount ; then
-        NETBOOT="nfs"
-        export NETBOOT
-        rc=0
-    fi
+	case ${NETBOOT} in 
+		nfs)
+			[ "$quiet" != "y" ] && log_begin_msg "Trying netboot from ${NFSROOT}"
+			if do_nfsmount ; then rc=0; fi 	;;
+		cifs)
+			[ "$quiet" != "y" ] && log_begin_msg "Trying netboot from ${NFSROOT}"
+			if do_cifsmount ; then rc=0; fi ;;
+		http|httpfs)
+			[ "$quiet" != "y" ] && log_begin_msg "Trying netboot from ${URL}"
+			if do_httpmount ; then rc=0; fi ;;
+	esac
 
     [ "$quiet" != "y" ] && log_end_msg
     return ${rc}
 }
 
+do_httpmount() {
+		rc=1
+		mkdir -p ${mountpoint}
+		mount -t tmpfs -o size=`wget ${URL} --spider --server-response -O - 2>&1 | sed -ne '/Content-Length/{s/.*: //;p}'` tmpfs ${mountpoint}
+		mkdir -p ${mountpoint}/casper
+        if wget ${URL} -O ${mountpoint}/casper/root.squashfs; then rc=0; fi
+		return ${rc}
+}
+
 do_nfsmount() {
     rc=1
     modprobe "${MP_QUIET}" nfs

boot.ipxe

#!ipxe
set server x.x.x.x
set path turnkey-core-14.1-jessie-amd64
#nslookup serverip ${server}
#set server ${serverip}
dhcp
kernel http://${server}/${path}/vmlinuz
initrd http://${server}/${path}/initrd.gz
imgargs vmlinuz boot=casper di-live single noinithooks ip=dhcp netboot=http fetch=http://${server}/${path}/10root.squashfs
boot || shell

pxelinux.cfg menu entry

label iPXE-TKL
        menu label iPXE ^Turnkey Linux
        kernel ipxe.krn dhcp && chain http://x.x.x.x/boot.ipxe || shell

grub2 menu entry (/etc/grub.d/99ipxe)

menuentry "iPXE" {
linux16 /ipxe.lkrn
initrd16 /boot.ipxe
}

patch-tkl-iso.sh

Sample shell script to extract kernel, initrd.gz and 10root.squashfs from a turnkey .iso file, and patch the initrd.gz image. Asumes .iso and .patch file is in the current working directory when run. Feel free to change according to taste.

(
export TKL=turnkey-core-14.1-jessie-amd64
rm -rf ./${TKL}
mkdir -p ./${TKL}.tmp.iso
mount -o loop ${TKL}.iso ${TKL}.tmp.iso
mkdir ./${TKL}
cd ./${TKL}
cp -r ../${TKL}.tmp.iso/casper/* .
umount ../${TKL}.tmp.iso
rm -r ../${TKL}.tmp.iso
mkdir -p initrd
cd initrd
gunzip -c ../initrd.gz | cpio -i
pwd
patch -p1 < ../../casper-http-simple.patch
find . | cpio -H newc -o | gzip -9 > ../initrd.gz
cd ..
rm -r initrd 
)

Previous post you've edited in from the pastebin contained the wrong patch, and some minor changes, as well as adding formatting to make the various file boundries clearer. Feel free to remove the chitchat and move this to the top after your reply Tue, 2016/05/17 - 10:59 . Cheers.