install 4/n: 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 take this file from the ISO this
network traffic won't happen so we need some other mechanism to fill the
server's ARP tables.

test-pingpxe.service is installed in install.img by iso-remaster.

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.

Similarly, once installed the host needs the same mechanism so the test
can find it.  We prepare an installer hook to install the service on the
host, which the generated answerfile will use in later commit.

This also takes into account xapi-project/xen-api#5799: we must avoid
sending out any traffic while the XAPI bridge has an obsolete MAC
attached, or the peer and network equipment in between get confused.

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

tests/install/conftest.py

@@ -13,7 +13,7 @@ def iso_remaster(request):
     param_mapping = marker.kwargs.get("param_mapping", {})
     iso_key = callable_marker(marker.args[0], request, param_mapping=param_mapping)
 
-    from data import ANSWERFILE_URL, ISO_IMAGES, ISOSR_SRV, ISOSR_PATH, TEST_SSH_PUBKEY, TOOLS
+    from data import ANSWERFILE_URL, ISO_IMAGES, 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)
@@ -36,6 +36,55 @@ def iso_remaster(request):
 
 mkdir -p "$INSTALLIMG/root/.ssh"
 echo "{TEST_SSH_PUBKEY}" > "$INSTALLIMG/root/.ssh/authorized_keys"
+
+cat > "$INSTALLIMG/usr/local/sbin/test-pingpxe.sh" << 'EOF'
+#! /bin/bash
+set -eE
+set -o pipefail
+
+ether_of () {{
+    ifconfig "$1" | grep ether | sed 's/.*ether \\([^ ]*\\).*/\\1/'
+}}
+
+# on installed system, avoid xapi-project/xen-api#5799
+if ! [ -e /opt/xensource/installer ]; then
+    eth_mac=$(ether_of eth0)
+    br_mac=$(ether_of xenbr0)
+
+    # wait for bridge MAC to be fixed
+    test "$eth_mac" = "$br_mac"
+fi
+
+ping -c1 "$1"
+EOF
+chmod +x "$INSTALLIMG/usr/local/sbin/test-pingpxe.sh"
+
+cat > "$INSTALLIMG/etc/systemd/system/test-pingpxe.service" <<EOF
+[Unit]
+Description=Ping pxe server to populate its ARP table
+After=network-online.target
+[Service]
+Type=oneshot
+ExecStart=/bin/sh -c 'while ! /usr/local/sbin/test-pingpxe.sh "{PXE_CONFIG_SERVER}"; do sleep 1 ; done'
+[Install]
+WantedBy=default.target
+EOF
+
+systemctl --root="$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"
+cp /usr/local/sbin/test-pingpxe.sh "\\$ROOT/usr/local/sbin/test-pingpxe.sh"
+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)