feat(pxe): one menu for every installable host, no per-host pxelinux configs

README.md

@@ -42,5 +42,5 @@ Dump test data:
 
 - Creates DHCPD configuration files
 - Creates DNS zone files for BIND
-- Creates PXE config files (with random secret for use with Puppet autosign)
+- Netboots hosts marked PXE installable, by setting their DHCP boot filename
 - Partial IPv6 support

mdb/admin.py

@@ -322,9 +322,6 @@ class OperatingSystemAdmin(admin.ModelAdmin):
         "name",
         "version",
         "arch",
-        "pxe_kernel",
-        "pxe_initrd",
-        "pxe_preseed_config_url",
     ]
 
 

mdb/fixtures/test_data.json

@@ -2740,9 +2740,6 @@
 },
 {
     "fields": {
-        "pxe_initrd": "path-to-initrd-for-os",
-        "pxe_kernel": "path-to-kernel-for-os",
-        "pxe_preseed_config_url": "http://url-to-preseed.config",
         "arch": "x86_64",
         "name": "Ubuntu",
         "version": "16.04-beta-final"

mdb/migrations/0015_drop_os_pxe_fields.py

@@ -0,0 +1,25 @@
+# Generated by Django 6.1.2 on 2026-11-04 20:26
+
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('mdb', '0014_classless_reverse_zone_names'),
+    ]
+
+    operations = [
+        migrations.RemoveField(
+            model_name='operatingsystem',
+            name='pxe_initrd',
+        ),
+        migrations.RemoveField(
+            model_name='operatingsystem',
+            name='pxe_kernel',
+        ),
+        migrations.RemoveField(
+            model_name='operatingsystem',
+            name='pxe_preseed_config_url',
+        ),
+    ]

mdb/models.py

@@ -4,7 +4,6 @@ import ipaddress
 from django.db import models
 from django.utils.translation import gettext_lazy as _
 
-from mdb.pxe import host_as_pxe_files
 from mdb.validators import validate_hostname, validate_macaddr
 
 
@@ -500,10 +499,6 @@ class OperatingSystem(models.Model):
         max_length=255, choices=OS_ARCHITECTURES, blank=True, null=True
     )
 
-    pxe_kernel = models.CharField(max_length=255, blank=True, null=True)
-    pxe_initrd = models.CharField(max_length=255, blank=True, null=True)
-    pxe_preseed_config_url = models.URLField(blank=True, null=True)
-
     def __str__(self):
         return self.name + " " + self.version + " (" + self.arch + ")"
 
@@ -540,9 +535,6 @@ class Host(models.Model):
     def __str__(self):
         return self.hostname
 
-    def as_pxe_files(self):
-        return host_as_pxe_files(self)
-
 
 class Interface(models.Model):
     name = models.CharField(max_length=128)

mdb/pxe.py

@@ -1,60 +0,0 @@
-import ipaddress
-
-from django.conf import settings
-from django.template.loader import render_to_string
-
-
-def render_pxelinux_cfg(_if, host):
-    """Renders pxelinux.cfg based on a host and the set of host interfaces.
-    If the host is tied to an OS with PXE fields set, it will use these instead of defaults."""
-    # Default config
-    kernel = settings.MDB_PXE_KERNEL
-    initrd = settings.MDB_PXE_INITRD
-    preseed_config_url = settings.MDB_PXE_PRESEED_URL
-
-    # Per host config (via OS model)
-    _os = host.operating_system
-    pxe_attrs = [_os.pxe_initrd, _os.pxe_kernel, _os.pxe_preseed_config_url]
-    if None not in pxe_attrs and "" not in pxe_attrs:
-        kernel = _os.pxe_kernel
-        initrd = _os.pxe_initrd
-        preseed_config_url = _os.pxe_preseed_config_url
-
-    context = {
-        "kernel": kernel,
-        "initrd": initrd,
-        "preseed_config_url": preseed_config_url,
-        "host": host,
-        "interface": _if,
-    }
-
-    return render_to_string("pxelinux.cfg", context=context)
-
-
-def get_pxe_filename(interface, filename_format="mac_addr"):
-    """
-    Mac or IP address based PXE filename
-    Ref: http://www.syslinux.org/wiki/index.php/PXELINUX#Examples
-    """
-    ip_addr_in_hex = f"{int(ipaddress.IPv4Address(interface.ip4address.address)):08X}"
-    formats = {
-        "ip_addr": ip_addr_in_hex,
-        "mac_addr": "01-{}".format(interface.macaddr.lower().replace(":", "-")),
-    }
-
-    return formats.get(filename_format, formats["mac_addr"])
-
-
-def host_as_pxe_files(host):
-    """Returns a list of filename,content for each host interface with an IPv4 address."""
-    from mdb.models import Host
-
-    assert isinstance(host, Host)
-
-    pxe_files = []
-    for _if in host.interface_set.exclude(ip4address__isnull=True):
-        filename = get_pxe_filename(_if)
-        content = render_pxelinux_cfg(_if, host)
-        pxe_files.append((filename, content))
-
-    return pxe_files

mdb/signals.py

@@ -1,9 +1,7 @@
 import ipaddress
 import logging
-import os
 import uuid
 
-from django.conf import settings
 from django.db.models.signals import post_save, pre_delete, pre_save
 from django.dispatch import receiver
 
@@ -89,10 +87,14 @@ def update_domain_serial_when_change_to_host(sender, instance, created, **kwargs
             subnet.save()
 
 
+# The netboot host serves one menu to every machine DHCP sends to pxelinux.
+PXE_FILENAME = "pxelinux.0"
+
+
 @receiver(post_save, sender=Host)
-def create_pxe_key_and_write_pxe_files_when_host_changes(
+def set_pxe_boot_when_host_changes(sender, instance, created, **kwargs):
-    sender, instance, created, **kwargs
+    """An installable host netboots into the menu; unticking it stops that.
-):
+    A filename other than pxelinux's is left alone either way."""
     host = instance
 
     if not host.pxe_key:
@@ -101,35 +103,20 @@ def create_pxe_key_and_write_pxe_files_when_host_changes(
         Host.objects.filter(pk=host.pk).update(pxe_key=pxe_key)
         host.pxe_key = pxe_key
 
-    for pxe_file_name, pxe_file in host.as_pxe_files():
+    for _if in host.interface_set.exclude(ip4address__isnull=True):
-        path = os.path.join(settings.MDB_PXE_TFTP_ROOT, pxe_file_name)
+        changed = False
         if host.pxe_installable:
-            # Write pxeconfig file to disk
+            if not _if.pxe_filename:
-            with open(path, "w+") as f:
+                _if.pxe_filename = PXE_FILENAME
-                f.write(pxe_file)
+                changed = True
-                logger.info(f"Created or updated {path}")
+            if not _if.dhcp_client:
-            os.chmod(path, 0o644)  # Not writeable for all
+                _if.dhcp_client = True
-
+                changed = True
-            # Also set necessary fields for pxe installation
+        elif _if.pxe_filename == PXE_FILENAME:
-            interfaces = host.interface_set.exclude(ip4address__isnull=True)
+            _if.pxe_filename = ""
-
+            changed = True
-            for _if in interfaces:
+        if changed:
-                changed = False
+            _if.save()
-                if not _if.pxe_filename:
-                    _if.pxe_filename = "pxelinux.0"  # don't overwrite
-                    changed = True
-                if not _if.dhcp_client:
-                    _if.dhcp_client = True
-                    changed = True
-
-                if changed:
-                    _if.save()
-
-        else:
-            if os.path.exists(path):
-                # Delete pxeconfig file from disk
-                os.unlink(path)
-                logger.info(f"deleted {path}")
 
 
 @receiver(pre_delete, sender=Interface)

mdb/templates/pxelinux.cfg

@@ -1,7 +0,0 @@
-default ninja
-prompt 0
-timeout 0
-
-label ninja
-  kernel {{kernel}}
-  append ramdisk_size=14984 locale=en_US console-setup/ask_detect=false keyboard-configuration/layoutcode=no netcfg/wireless_wep= netcfg_choose_interface=eth0 netcfg/get_hostname= preseed/url={{preseed_config_url}} vga=normal snop={{host.pxe_key}} initrd={{initrd}} -- quiet

mdbsite/settings.py

@@ -123,12 +123,6 @@ REST_FRAMEWORK = {
     "DEFAULT_PERMISSION_CLASSES": ("rest_framework.permissions.IsAuthenticated",),
 }
 
-# PXE
-MDB_PXE_TFTP_ROOT = "/var/lib/tftpboot/pxelinux/pxelinux.cfg/"
-MDB_PXE_KERNEL = "ubuntu/14_04/amd64/alternate/linux"
-MDB_PXE_INITRD = "ubuntu/14_04/amd64/alternate/initrd.gz"
-MDB_PXE_PRESEED_URL = "http://158.36.190.194/ubuntu/preseed_1404.cfg"
-
 # Sentry
 SENTRY_DSN = os.getenv("SENTRY_DSN")
 SENTRY_ENVIRONMENT = os.getenv("SENTRY_ENVIRONMENT", "dev")

tests/test_pxe.py

@@ -1,11 +1,9 @@
 import pytest
-from django.conf import settings
 from django.contrib import messages
 from django.core.management import call_command
 from django.urls import reverse
 
-from mdb.models import Host, Interface, OperatingSystem
+from mdb.models import Host, Interface
-from mdb.pxe import get_pxe_filename, render_pxelinux_cfg
 
 
 @pytest.fixture
@@ -18,85 +16,48 @@ def host(db_with_fixtures):
     return Host.objects.first()
 
 
-@pytest.mark.django_db
+def test_saving_installable_host_boots_it_from_the_network(host):
-def test_render_pxeconfig(host):
-    interface = host.interface_set.exclude(ip4address__isnull=True).first()
-    config = render_pxelinux_cfg(interface, host)
-
-    assert settings.MDB_PXE_INITRD in config
-    assert settings.MDB_PXE_KERNEL in config
-    assert settings.MDB_PXE_PRESEED_URL in config
-
-
-@pytest.mark.django_db
-def test_render_pxeconfig_with_os_pxe_config(host):
-    _os = OperatingSystem.objects.get(pk=2)  # OS with all pxe vars set
-    Host.objects.filter(pk=host.pk).update(operating_system=_os)
-    host = Host.objects.first()
-
-    interface = host.interface_set.exclude(ip4address__isnull=True).first()
-    config = render_pxelinux_cfg(interface, host)
-
-    assert _os.pxe_initrd in config
-    assert _os.pxe_kernel in config
-    assert _os.pxe_preseed_config_url in config
-
-
-@pytest.mark.django_db
-def test_host_as_pxe_files(host):
-    assert len(host.as_pxe_files()) == 1
-
-
-PXE_FILE = "01-f0-de-f1-58-be-1a"  # from the fixture interface's MAC address
-
-
-@pytest.fixture
-def tftp_root(settings, tmp_path):
-    settings.MDB_PXE_TFTP_ROOT = str(tmp_path)
-    return tmp_path
-
-
-def test_saving_installable_host_writes_pxe_file(host, tftp_root):
     Interface.objects.update(pxe_filename="", dhcp_client=False)
     host.save()
 
-    path = tftp_root / PXE_FILE
-    assert host.pxe_key in path.read_text()
-    assert path.stat().st_mode & 0o777 == 0o644
-    # The interface is set up to boot from the network.
     interface = host.interface_set.get()
     assert interface.pxe_filename == "pxelinux.0"
     assert interface.dhcp_client
 
 
-def test_saving_host_keeps_custom_pxe_filename(host, tftp_root):
+def test_saving_host_keeps_custom_pxe_filename(host):
     Interface.objects.update(pxe_filename="custom.efi")
     host.save()
     assert host.interface_set.get().pxe_filename == "custom.efi"
 
 
-def test_saving_non_installable_host_deletes_pxe_file(host, tftp_root):
+def test_saving_non_installable_host_stops_netboot(host):
-    (tftp_root / PXE_FILE).write_text("old")
+    Interface.objects.update(pxe_filename="pxelinux.0", dhcp_client=True)
     host.pxe_installable = False
     host.save()
-    assert not (tftp_root / PXE_FILE).exists()
+
+    interface = host.interface_set.get()
+    assert interface.pxe_filename == ""
+    # The host keeps its address.
+    assert interface.dhcp_client
 
 
-def test_saving_host_without_key_generates_one(host, tftp_root):
+def test_saving_non_installable_host_keeps_custom_pxe_filename(host):
+    Interface.objects.update(pxe_filename="custom.efi")
+    host.pxe_installable = False
+    host.save()
+    assert host.interface_set.get().pxe_filename == "custom.efi"
+
+
+def test_saving_host_without_key_generates_one(host):
     host.pxe_key = ""
     host.save()
-    key = Host.objects.get(pk=host.pk).pxe_key
+    assert len(Host.objects.get(pk=host.pk).pxe_key) == 32
-    assert len(key) == 32
-    assert key in (tftp_root / PXE_FILE).read_text()
 
 
-def test_pxe_filename_by_ip_address(host):
+def test_admin_marks_hosts_installable(host, admin_client):
-    interface = host.interface_set.get()  # 10.0.3.2
-    assert get_pxe_filename(interface, "ip_addr") == "0A000302"
-
-
-def test_admin_marks_hosts_installable(host, tftp_root, admin_client):
     Host.objects.update(pxe_installable=False)
+    Interface.objects.update(pxe_filename="")
 
     res = admin_client.post(
         reverse("admin:mdb_host_changelist"),
@@ -106,11 +67,11 @@ def test_admin_marks_hosts_installable(host, tftp_root, admin_client):
 
     assert res.status_code == 200
     assert Host.objects.get(pk=host.pk).pxe_installable
-    assert (tftp_root / PXE_FILE).exists()
+    assert host.interface_set.get().pxe_filename == "pxelinux.0"
     assert not [m for m in res.context["messages"] if m.level == messages.WARNING]
 
 
-def test_admin_warns_about_interfaces_without_ip(host, tftp_root, admin_client):
+def test_admin_warns_about_interfaces_without_ip(host, admin_client):
     Host.objects.update(pxe_installable=False)
     Interface.objects.create(
         name="eth1", macaddr="00:11:22:33:44:55", host=host, domain_id=1