feat(migration): export UniFi config and generate VyOS DHCP+DNS from it

Groundwork for replacing the USG with the VyOS pair without anything on the network noticing. Three pieces: migration/unifi-export.py pulls 13 endpoints off the classic controller into timestamped JSON plus a normalised inventory: 11 networks, 31 DHCP reservations, 4 port forwards, 2 firewall rules, 0 static routes. Two things this turned up that a naive export would have lost: - 23 of the 31 reservations carry no network_id at all -- UniFi simply does not store the binding -- so they are resolved by subnet containment instead. Without that, three quarters of the reservations have no subnet to be placed in. - 30 of the 31 sit INSIDE the DHCP pool, which UniFi's dhcpd tolerates and which is flagged as a warning rather than discovered at cutover. migration/unifi-to-vyos.py turns that inventory into VyOS `set` commands for DHCP and DNS only -- the services the USG owns that VyOS must reproduce. Not a general converter. --prod and --sim come from one code path so the config proven in the sim and the config applied to the firewalls cannot drift. Prod mode hard-fails if any reservation is missing, since a silent drop is the failure mode that matters. DNS is included because the USG resolves for 5 of 6 VLANs today: UniFi hands out the gateway's own address whenever dhcpd_dns is empty, verified by labmaster resolving against 192.168.8.1. Replacing the USG without a forwarder would take DNS away from those VLANs entirely. labsim/labsim-dhcp-test.sh proves it by booting throwaway VMs with real production MACs -- the one piece of production config that transplants verbatim. Safe because ovs-labsim has no physical NIC, so those MACs cannot reach the real LAN. Result on VyOS 2026.08 (kea), 4/4: printer1 got 172.31.10.46 from inside the pool, sonoff-matter got 172.31.11.67 across the /23 boundary, Hubitat got its out-of-pool .2, and an unreserved MAC got an unreserved address. kea honours in-pool host reservations -- the open question blocking the cutover. Supporting changes to labsim: - VLAN 10 widened to /23. Every reservation is in LoT and LoT spans 10.0.0.x and 10.0.1.x, which a /24 cannot represent. - LoT's host leg moved to .3, because 10.0.0.2 is a real reservation (Hubitat) that maps onto the host's own address. - vlans.conf gained optional masklen and host_octet fields, defaulting to 24 and 2 so the other five VLANs are untouched. - Fixed /etc/network/interfaces hardcoding 255.255.255.0. That file is what actually takes effect on these Alpine guests -- cloud-init's network-config is ignored -- so any non-/24 VLAN was silently wrong. Two generator bugs found by VyOS rejecting the output: static-mapping names are validated as hostnames, so underscores fail; and two devices named "espressif" plus two named "thebeast" collided into single names, which would have overwritten one reservation with another's address. The raw export holds WiFi passphrases and the WAN PPPoE credentials and is gitignored. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01DMVzWZgiKW2wquf5z8S1yH
2026-08-15 01:33:00 +01:00
parent b0b68f2edd
commit 44dbd5188c
11 changed files with 934 additions and 15 deletions
--- a/labsim/README.md
+++ b/labsim/README.md
@@ -15,10 +15,27 @@ Each VLAN is its own isolated libvirt network with one tiny Alpine VM on it.
 | 2 | k8s | 172.31.2.0/24 | 172.31.2.10 | 192.168.8.0/23 |
 | 3 | kvm | 172.31.3.0/24 | 172.31.3.10 | 192.168.3.0/24 |
 | 9 | private | 172.31.9.0/24 | 172.31.9.10 | 10.0.9.0/23 |
-| 10 | lot | 172.31.10.0/24 | 172.31.10.10 | 10.0.0.0/23 |
+| 10 | lot | **172.31.10.0/23** | 172.31.10.10 | 10.0.0.0/23 |
 | 200 | roomates | 172.31.200.0/24 | 172.31.200.10 | 192.168.2.0/24 |

-The sim subnet always encodes the VLAN id: `172.31.<vlan>.0/24`.
+The sim subnet encodes the VLAN id: `172.31.<vlan>.0/24`, with one exception.
+**VLAN 10 is a `/23`** because every UniFi DHCP reservation lives in LoT and LoT
+spans `10.0.0.x` *and* `10.0.1.x`, which a `/24` cannot hold. The mapping stays
+readable — `10.0.0.46 → 172.31.10.46`, `10.0.1.67 → 172.31.11.67`.
+
+LoT's host leg is `.3`, not `.2`, because `10.0.0.2` is a real reservation
+(Hubitat) that maps onto `172.31.10.2`. `.3` is unreserved and sits below the
+DHCP pool, so it can never be handed out.
+
+`vlans.conf` therefore takes two optional trailing fields:
+
+```
+vlan_id:name:sim_prefix:real_subnet[:masklen][:host_octet]
+```
+
+defaulting to `24` and `2`. k8s and Private are also `/23` in production but
+hold no reservations, so they keep their `/24` and their DHCP range is clamped
+— reported at generation time, never silently.

 Address plan, identical on every VLAN:

@@ -69,6 +86,32 @@ sudo virsh console labsim-2-k8s     # root / labsim
 ./monitoring-up.sh               # topology page + Prometheus + Grafana
 ```

+## Testing the DHCP migration
+
+`./labsim-dhcp-test.sh` boots throwaway VMs whose MACs are **real production
+MACs** and checks each gets the address UniFi reserved for it. MACs are the one
+piece of production config that transplants verbatim, which is what makes this a
+test rather than a rehearsal. It is safe because `ovs-labsim` has no physical
+NIC — verified with `ovs-vsctl show` — so a production MAC cannot reach the real
+LAN.
+
+Apply the config first, from `../migration`:
+
+```bash
+python3 unifi-to-vyos.py --mode sim -o /tmp/sim.conf   # 6 subnets, 31 mappings
+# load onto labsim-vyos, then:
+./labsim-dhcp-test.sh
+```
+
+**Result on VyOS 2026.08 (kea): all four cases pass.** The one that mattered:
+30 of the 31 UniFi reservations sit *inside* the DHCP pool, and **kea honours
+in-pool host reservations** — `printer1` received `172.31.10.46` from within the
+`.10.11–.11.254` pool. That was the open question blocking the cutover.
+
+Still open: whether kea will hand a *reserved* address to a *different* client
+while the reserved device is offline. The negative case here only proves an
+unreserved MAC gets an unreserved address.
+
 - **http://localhost:9101/** — live mesh: a node per VLAN, the router in the
  middle, one line per pair coloured green/red with the ICMP RTT on it. Hover a
  line for per-direction detail. Refreshes every 5s. This is the one to watch
--- a/labsim/labsim-dhcp-test.sh
+++ b/labsim/labsim-dhcp-test.sh
@@ -0,0 +1,189 @@
+#!/bin/bash
+# Prove that VyOS hands each device the address UniFi reserved for it.
+#
+# The question this answers is narrow and important: 30 of the 31 UniFi
+# reservations sit INSIDE the DHCP pool (LoT's pool is 10.0.0.11-10.0.1.254 and
+# only 10.0.0.2 falls outside it). UniFi's dhcpd tolerates that. VyOS uses kea,
+# and whether kea honours in-pool host reservations decides whether the cutover
+# silently renumbers 30 devices. That is not something to predict.
+#
+# Method: boot throwaway VMs whose MAC is a REAL production MAC, on the sim
+# VLAN, and check the address they are given. MACs are the one piece of
+# production config that transplants verbatim -- the subnet is rewritten, the
+# MAC is not -- which is what makes this a real test rather than a rehearsal.
+#
+# Safe: the ovs-labsim bridge contains only internal ports and VM taps, with no
+# physical NIC, so a production MAC here cannot reach or confuse the real LAN.
+# Verified with `ovs-vsctl show` before this script was written.
+#
+#   ./labsim-dhcp-test.sh              run the standard cases
+#   ./labsim-dhcp-test.sh --keep       leave the VMs up for inspection
+#   ./labsim-dhcp-test.sh --clean      just remove any leftover test VMs
+set -uo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
+source "$SCRIPT_DIR/lib.sh"
+
+ROUTER_IP="${ROUTER_IP:-172.31.1.1}"
+ROUTER_PW="${ROUTER_PW:-vyos}"
+TEST_VLAN="${TEST_VLAN:-10}"
+BOOT_WAIT="${BOOT_WAIT:-150}"
+TAG="labsim-dhcptest"
+
+# mac|expected|why. "POOL" means: must get an address from the pool and must
+# NOT get any reserved address -- the negative case that stops a pass from
+# meaning merely "DHCP works".
+CASES=(
+  "f8:0d:ac:90:65:c6|172.31.10.46|printer1 - reservation inside the pool"
+  "1c:69:20:7f:bc:77|172.31.11.67|sonoff-matter - in-pool AND across the /23 boundary"
+  "34:e1:d1:80:29:ce|172.31.10.2|Hubitat - the one reservation OUTSIDE the pool"
+  "52:54:00:ab:cd:ef|POOL|unreserved MAC - must get a pool address, not a reserved one"
+)
+
+vm_of() { echo "${TAG}-$(echo "$1" | tr -d ':')"; }
+
+cleanup_vms() {
+  local n=0
+  while read -r vm; do
+    [ -z "$vm" ] && continue
+    virsh_q destroy "$vm" >/dev/null 2>&1
+    virsh_q undefine "$vm" --remove-all-storage >/dev/null 2>&1
+    n=$((n + 1))
+  done < <(virsh_q list --all --name 2>/dev/null | grep "^${TAG}-" || true)
+  [ "$n" -gt 0 ] && log "removed $n test VM(s)"
+  sudo rm -f "$IMG_DIR/${TAG}-"*.qcow2 "$IMG_DIR/${TAG}-"*-seed.iso 2>/dev/null
+  return 0
+}
+
+# A seed that asks for DHCP instead of taking a static address. Alpine's
+# cloud-init ignores network-config here (verified previously and documented in
+# README), so /etc/network/interfaces is what actually takes effect.
+build_dhcp_seed() {
+  local iso="$1" vm="$2" pubkey="$3"
+  local tmp; tmp="$(mktemp -d)"
+  cat > "$tmp/meta-data" <<EOF
+instance-id: $vm
+local-hostname: $vm
+EOF
+  cat > "$tmp/user-data" <<EOF
+#cloud-config
+hostname: $vm
+users:
+  - name: alpine
+    shell: /bin/ash
+    lock_passwd: false
+    plain_text_passwd: labsim
+    ssh_authorized_keys:
+      - $pubkey
+ssh_authorized_keys:
+  - $pubkey
+disable_root: false
+chpasswd:
+  list: |
+    root:labsim
+  expire: false
+write_files:
+  - path: /etc/network/interfaces
+    content: |
+      auto lo
+      iface lo inet loopback
+      auto eth0
+      iface eth0 inet dhcp
+runcmd:
+  - [ sh, -c, "ifdown eth0 2>/dev/null; ifup eth0 || udhcpc -i eth0 -q || true" ]
+EOF
+  python3 - "$tmp/user-data" <<'PY' || die "generated user-data is not valid YAML"
+import sys, yaml
+yaml.safe_load(open(sys.argv[1]).read().split("#cloud-config",1)[1])
+PY
+  sudo genisoimage -quiet -output "$iso" -volid cidata -joliet -rock \
+    "$tmp/user-data" "$tmp/meta-data" >/dev/null 2>&1 || die "seed build failed"
+  rm -rf "$tmp"
+}
+
+router() {
+  timeout 30 sshpass -p "$ROUTER_PW" ssh -o StrictHostKeyChecking=no \
+    -o BatchMode=no -o ConnectTimeout=8 "vyos@$ROUTER_IP" "$@" 2>/dev/null
+}
+
+# --- argument handling ----------------------------------------------------
+KEEP=0
+case "${1:-}" in
+  --clean) cleanup_vms; exit 0 ;;
+  --keep)  KEEP=1 ;;
+  "")      ;;
+  *)       die "usage: $0 [--keep|--clean]" ;;
+esac
+
+command -v sshpass >/dev/null || die "sshpass required"
+require_tools
+[ -f "$BASE_IMAGE" ] || die "base image missing: $BASE_IMAGE (run labsim-up.sh first)"
+
+log "checking the router is serving DHCP..."
+subnets=$(router '/opt/vyatta/bin/vyatta-op-cmd-wrapper show configuration commands | grep -c subnet-id')
+maps=$(router '/opt/vyatta/bin/vyatta-op-cmd-wrapper show configuration commands | grep -c "static-mapping .* mac"')
+log "  router has ${subnets:-0} subnets and ${maps:-0} static-mappings"
+[ "${maps:-0}" -gt 0 ] || die "router has no static-mappings -- apply the generated config first"
+
+cleanup_vms
+SSH_PUB="$(find_ssh_pubkey)"
+sudo mkdir -p "$IMG_DIR"
+
+# --- boot one VM per case -------------------------------------------------
+for c in "${CASES[@]}"; do
+  IFS='|' read -r mac expected why <<<"$c"
+  vm="$(vm_of "$mac")"
+  disk="$IMG_DIR/${vm}.qcow2"; seed="$IMG_DIR/${vm}-seed.iso"
+  log "booting $vm  mac=$mac  ($why)"
+  sudo qemu-img create -q -f qcow2 -F qcow2 -b "$BASE_IMAGE" "$disk" "$VM_DISK" >/dev/null
+  build_dhcp_seed "$seed" "$vm" "$SSH_PUB"
+  sudo virt-install --connect "$LIBVIRT_URI" --name "$vm" \
+    --memory "$VM_MEM" --vcpus "$VM_CPUS" \
+    --disk "path=$disk,format=qcow2,bus=virtio" \
+    --disk "path=$seed,device=cdrom,readonly=on" \
+    --network "network=labsim-ovs,portgroup=vlan${TEST_VLAN},model=virtio,mac=$mac" \
+    --os-variant alpinelinux3.18 --graphics none --noautoconsole --import >/dev/null \
+    || die "virt-install failed for $vm"
+done
+
+log "waiting ${BOOT_WAIT}s for boot + DHCP..."
+sleep "$BOOT_WAIT"
+
+# --- verdict --------------------------------------------------------------
+# The lease table on the router is the authority: it says what the server
+# decided, independent of whether the guest brought the interface up cleanly.
+leases="$(router '/opt/vyatta/bin/vyatta-op-cmd-wrapper show dhcp server leases')"
+echo
+echo "=== router lease table ==="
+echo "$leases"
+echo
+
+reserved_ips="$(cd "$SCRIPT_DIR/../migration" && python3 unifi-to-vyos.py --mode sim 2>/dev/null \
+  | awk '/static-mapping .* ip-address/ {print $NF}')"
+
+pass=0; fail=0
+printf '%-19s %-16s %-16s %s\n' "MAC" "EXPECTED" "GOT" "RESULT"
+for c in "${CASES[@]}"; do
+  IFS='|' read -r mac expected why <<<"$c"
+  got="$(echo "$leases" | awk -v m="$mac" 'tolower($0) ~ tolower(m) {print $1; exit}')"
+  got="${got:-<none>}"
+  if [ "$expected" = "POOL" ]; then
+    if [ "$got" = "<none>" ]; then
+      result="FAIL (no lease at all)"
+    elif echo "$reserved_ips" | grep -qx "$got"; then
+      result="FAIL (got a RESERVED address)"
+    else
+      result="pass"
+    fi
+  else
+    [ "$got" = "$expected" ] && result="pass" || result="FAIL"
+  fi
+  [ "$result" = "pass" ] && pass=$((pass + 1)) || fail=$((fail + 1))
+  printf '%-19s %-16s %-16s %s\n' "$mac" "$expected" "$got" "$result"
+  printf '  %s\n' "$why"
+done
+
+echo
+log "$pass passed, $fail failed"
+[ "$KEEP" -eq 1 ] && log "VMs left running (--keep). Remove with: $0 --clean" || cleanup_vms
+[ "$fail" -eq 0 ] || exit 1
--- a/labsim/labsim-matrix.py
+++ b/labsim/labsim-matrix.py
@@ -78,9 +78,15 @@ def load_vlans() -> list[dict]:
            line = line.strip()
            if not line or line.startswith("#"):
                continue
-            vid, name, prefix, real = line.split(":", 3)
+            # masklen and host_octet are optional trailing fields; VLAN 10 sets
+            # both because it must be a /23 (see vlans.conf).
+            parts = line.split(":")
+            vid, name, prefix, real = parts[0], parts[1], parts[2], parts[3]
+            masklen = int(parts[4]) if len(parts) > 4 and parts[4] else 24
+            host = parts[5] if len(parts) > 5 and parts[5] else "2"
            vlans.append({"vid": vid, "name": name, "ip": f"{prefix}.10",
-                          "label": f"{vid}:{name}", "real": real})
+                          "label": f"{vid}:{name}", "real": real,
+                          "masklen": masklen, "host_ip": f"{prefix}.{host}"})
    return vlans


--- a/labsim/labsim-up.sh
+++ b/labsim/labsim-up.sh
@@ -25,7 +25,8 @@ ovs_up

 # --- VMs ------------------------------------------------------------------
 for entry in "${SELECTED[@]}"; do
-  IFS=: read -r vid name prefix real <<<"$entry"
+  parse_vlan_entry "$entry"
+  vid="$V_VID"; name="$V_NAME"; prefix="$V_PREFIX"; real="$V_REAL"
  vm="$(vm_name "$vid" "$name")"
  ip="${prefix}.10"

@@ -48,7 +49,7 @@ for entry in "${SELECTED[@]}"; do
  # Copy-on-write overlay: each VM costs a few MB, not 176.
  sudo qemu-img create -q -f qcow2 -F qcow2 -b "$BASE_IMAGE" "$disk" "$VM_DISK" >/dev/null

-  build_seed "$seed" "$vm" "$vid" "$name" "$prefix" "$ip" "$real" "$SSH_PUB"
+  build_seed "$seed" "$vm" "$vid" "$name" "$prefix" "$ip" "$real" "$SSH_PUB" "$V_MASK"

  sudo virt-install \
    --connect "$LIBVIRT_URI" \
--- a/labsim/lib.sh
+++ b/labsim/lib.sh
@@ -58,9 +58,32 @@ selected_vlans() {
  [ ${#SELECTED[@]} -gt 0 ] || die "no VLANs selected (checked $CONF)"
 }

+# Split one vlans.conf line, applying defaults for the two optional trailing
+# fields. Sets V_VID V_NAME V_PREFIX V_REAL V_MASK V_HOST.
+parse_vlan_entry() {
+  IFS=: read -r V_VID V_NAME V_PREFIX V_REAL V_MASK V_HOST <<<"$1"
+  V_MASK="${V_MASK:-24}"
+  V_HOST="${V_HOST:-2}"
+}
+
+# Dotted netmask for a prefix length — cloud-init's network-config v1 wants the
+# dotted form, not a /len. /24 -> 255.255.255.0, /23 -> 255.255.254.0.
+netmask_for() {
+  local len="$1" i bits out=()
+  for i in 0 1 2 3; do
+    bits=$(( len - i * 8 ))
+    (( bits > 8 )) && bits=8
+    (( bits < 0 )) && bits=0
+    out+=( $(( 256 - 2 ** (8 - bits) )) )
+  done
+  local IFS=.; echo "${out[*]}"
+}
+
 # cloud-init NoCloud seed: static addressing + SSH key + hello-world HTTP.
 build_seed() {
  local iso="$1" vm="$2" vid="$3" name="$4" prefix="$5" ip="$6" real="$7" pubkey="$8"
+  local masklen="${9:-24}"
+  local netmask; netmask="$(netmask_for "$masklen")"
  local tmp; tmp="$(mktemp -d)"

  cat > "$tmp/meta-data" <<EOF
@@ -85,7 +108,7 @@ config:
    subnets:
      - type: static
        address: $ip
-        netmask: 255.255.255.0
+        netmask: $netmask
        # Default route via the router under test. Without this the VMs can
        # reach their own /24 and their gateway, but nothing beyond it — which
        # looks exactly like "the router is broken" in the matrix.
@@ -122,14 +145,14 @@ write_files:
      auto eth0
      iface eth0 inet static
        address $ip
-        netmask 255.255.255.0
+        netmask $netmask
        post-up ip route add default via ${prefix}.1 || true
  - path: /var/www/index.html
    content: |
      <html><body>
      <h1>labsim vlan $vid — $name</h1>
      <p>host: $vm</p>
-      <p>address: $ip/24</p>
+      <p>address: $ip/$masklen</p>
      <p>gateway under test: ${prefix}.1</p>
      <p>mirrors production: $real</p>
      </body></html>
--- a/labsim/ovs.sh
+++ b/labsim/ovs.sh
@@ -41,12 +41,15 @@ ovs_up() {
  # default route (.1 is), so inter-VLAN tests exercise the router, not the
  # host's routing table.
  for entry in "${SELECTED[@]}"; do
-    IFS=: read -r vid _name prefix _real <<<"$entry"
-    local port="hostv${vid}"
-    ovs --may-exist add-port "$OVS_BR" "$port" tag="$vid" \
+    parse_vlan_entry "$entry"
+    local port="hostv${V_VID}"
+    ovs --may-exist add-port "$OVS_BR" "$port" tag="$V_VID" \
      -- set interface "$port" type=internal
    sudo ip link set "$port" up 2>/dev/null || true
-    sudo ip addr replace "${prefix}.2/24" dev "$port"
+    # Drop any address from a previous mask/octet so a changed vlans.conf does
+    # not leave a stale second address on the port.
+    sudo ip -4 addr flush dev "$port" 2>/dev/null || true
+    sudo ip addr replace "${V_PREFIX}.${V_HOST}/${V_MASK}" dev "$port"
  done

  ovs_define_libvirt_net
--- a/labsim/vlans.conf
+++ b/labsim/vlans.conf
@@ -12,10 +12,21 @@
 #   .10   the micro VM for this VLAN
 #   .254  VRRP VIP             (reserved, mirrors production)
 #
-# Format: vlan_id:name:sim_subnet_prefix:real_subnet(for reference)
+# Format: vlan_id:name:sim_subnet_prefix:real_subnet:[masklen]:[host_octet]
+#
+# masklen defaults to 24 and host_octet to 2. Both exist for VLAN 10, which is
+# the one VLAN that has to be a /23 here: every UniFi DHCP reservation lives in
+# LoT, and LoT spans 10.0.0.x AND 10.0.1.x, which a /24 cannot represent. With
+# /23 the mapping stays readable — 10.0.0.46 -> 172.31.10.46 and
+# 10.0.1.67 -> 172.31.11.67.
+#
+# LoT's host leg is .3 rather than .2 because 10.0.0.2 is a real reservation
+# (Hubitat) and would map straight onto the host's own address. .3 is free in
+# production and sits below the DHCP pool (which starts at .11), so it can
+# never be handed out.
 1:management:172.31.1:192.168.1.0/24
 2:k8s:172.31.2:192.168.8.0/23
 3:kvm:172.31.3:192.168.3.0/24
 9:private:172.31.9:10.0.9.0/23
-10:lot:172.31.10:10.0.0.0/23
+10:lot:172.31.10:10.0.0.0/23:23:3
 200:roomates:172.31.200:192.168.2.0/24