Make sure host appears in PXE ARP tables

Detection of host IP till now relies on the fact we download the
answerfile from PXE server.  Once we generate it this network traffic
won't happen so we need some other mechanism to fill the server's ARP
tables.  Similarly, once installed the host needs the same mechanism
so the test can find it.

test-pingpxe.service is installed in install.img by iso-remaster, and
copied to host using an installer hook.

Since it is difficult to wait until the IP has been assigned before
launching the service, make it ping continuously until we can reach
the PXE server.

Signed-off-by: Yann Dirson <[email protected]>

Author: ydirson

conftest.py

@@ -293,7 +293,7 @@ def answerfile(request):
 def iso_remaster(answerfile):
     SOURCE_ISO = "/home/user/iso/xcp-ng-8.2.1-20231130.iso" # FIXME dict in data.py
 
-    from data import ISOSR_SRV, ISOSR_PATH, TEST_SSH_PUBKEY, TOOLS
+    from data import ISOSR_SRV, ISOSR_PATH, PXE_CONFIG_SERVER, TEST_SSH_PUBKEY, TOOLS
     assert "iso-remaster" in TOOLS
     iso_remaster = TOOLS["iso-remaster"]
     assert os.access(iso_remaster, os.X_OK)
@@ -306,6 +306,10 @@ def iso_remaster(answerfile):
 
         if answerfile:
             logging.info("generating answerfile %s", answerfile_xml)
+            import xml.etree.ElementTree as ET
+            ET.SubElement(answerfile.getroot(), "script",
+                          stage="filesystem-populated",
+                          type="url").text = "file:///root/postinstall.sh"
             answerfile.write(answerfile_xml)
         else:
             logging.info("no answerfile")
@@ -323,6 +327,32 @@ def iso_remaster(answerfile):
 
 test ! -e "{answerfile_xml}" ||
     cp "{answerfile_xml}" "$INSTALLIMG/root/answerfile.xml"
+
+cat > "$INSTALLIMG/etc/systemd/system/test-pingpxe.service" <<EOF
+[Unit]
+Description=Ping pxe server to populate its ARP table
+After=network-online.target
+[Service]
+Type=oneshot
+ExecStart=/bin/sh -c 'while ! ping -c1 {PXE_CONFIG_SERVER}; do sleep 1 ; done'
+[Install]
+WantedBy=default.target
+EOF
+
+systemctl --root="$INSTALLIMG" enable test-pingpxe.service
+
+cat > "$INSTALLIMG/root/postinstall.sh" <<EOF
+#!/bin/sh
+set -ex
+
+ROOT="\\$1"
+
+cp /etc/systemd/system/test-pingpxe.service "\\$ROOT/etc/systemd/system/test-pingpxe.service"
+systemctl --root="\\$ROOT" enable test-pingpxe.service
+
+mkdir -p "\\$ROOT/root/.ssh"
+echo "{TEST_SSH_PUBKEY}" >> "\\$ROOT/root/.ssh/authorized_keys"
+EOF
 """,
                   file=patcher_fd)
             os.chmod(patcher_fd.fileno(), 0o755)