ipxe: Add new ability to boot fixed installer version

We need to boot any installer of distribution independent on DISTRI
and VERSION variables. New variable IPXE_BOOT_FIXED indicates that we
want to boot fixed version. It will boot by default SLE 15-SP6, but it
is possible to override it by IPXE_BOOT_FIXED_DISTRI and
IPXE_BOOT_FIXED_VERSION variables.

tests/installation/ipxe_install.pm

@@ -57,10 +57,17 @@ sub set_pxe_boot {
 }
 
 sub set_bootscript {
+    my $distri;
+    my $version;
+    if (get_var('IPXE_BOOT_FIXED')) {
+        $distri = get_var('IPXE_BOOT_FIXED_DISTRI', 'sle');
+        $version = get_var('IPXE_BOOT_FIXED_VERSION', '15-SP6');
+    } else {
+        $distri = is_sle_micro('>=6.1') ? "SL-Micro" : get_required_var('DISTRI');
+        $version = get_required_var('VERSION');
+    }
     my $host = get_required_var('SUT_IP');
-    my $distri = is_sle_micro('>=6.1') ? "SL-Micro" : get_required_var('DISTRI');
     my $arch = get_required_var('ARCH');
-    my $version = get_required_var('VERSION');
     my $autoyast = get_var('AUTOYAST', '');
     my $mirror_http = get_required_var('MIRROR_HTTP');
 

variables.md

@@ -103,6 +103,9 @@ INSTALLONLY | boolean | false | Indicates that test suite conducts only installa
 INSTLANG | string | en_US | Installation locale settings.
 IPERF_REPO | string | | Link to repository with iperf tool for network performance testing. Currently used in Public Cloud Azure test
 IPXE | boolean | false | Indicates ipxe boot.
+IPXE_BOOT_FIXED | boolean | false | Indicates to ipxe boot fixed distribution independent on DISTRI and VERSION variables.
+IPXE_BOOT_FIXED_DISTRI | string | sle | Sets distribution name for fixed ipxe boot.
+IPXE_BOOT_FIXED_VERSION | string | 15-SP6 | Sets distribution version for fixed ipxe boot.
 IPXE_SET_HDD_BOOTSCRIPT | boolean | false | Upload second IPXE boot script for booting from HDD after the installation boot script gets executed. This is a workaround for cases where the installer fails to switch default boot order to HDD boot. See also PXE_BOOT_TIME.
 ISO_MAXSIZE | integer | | Max size of the iso, used in `installation/isosize.pm`.
 IS_MM_SERVER | boolean | | If set, run server-specific part of the multimachine job