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lab/labsim/labsim-down.sh

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feat(labsim): libvirt replica of the lab network with LACP + VyOS routing A throwaway copy of the production VLAN topology so routing and firewall changes can be tested before they touch the real network. Same VLAN IDs and roles as UniFi, deliberately different ranges (172.31.<vlan>.0/24) so nothing here can be mistaken for production. - OVS fabric: real 802.1Q. Access port per micro VM, host leg per VLAN (.2, for SSH only — NOT the VMs' default route, so inter-VLAN tests exercise the router rather than the host's routing table), and a trunk portgroup with VLAN 1 declared nativeMode='untagged'. - Six Alpine micro VMs (256MB, copy-on-write overlays on one 176MB image), SSH + a hello-world HTTP page naming the VLAN. - VyOS router installed to disk unattended over the console, with the SAME config shape as the VP2440s: two NICs in an LACP bond carrying the trunk, VLAN 1 native, bond0.<vlan> holding the .1 gateway on each. - labsim-matrix.py: full-mesh ICMP/TCP22/TCP80 probe, ~0.2s, --watch highlights cells that changed since the last sweep. Guest-side probe is python3 (already present via cloud-init) so nothing is installed on VMs that have no internet. - Prometheus + Grafana (anonymous auth, no login) with a provisioned dashboard: heatmap plus a state timeline showing exactly when a path flipped. Verified end to end: one VyOS rule took sum(labsim_reachable) from 90 to 84, blocking precisely kvm<->k8s across all three protocols. Traps found building this, all now encoded in the scripts: - virtio-net breaks 802.3ad: the guest's bonding driver reports slaves "MII Status: down" despite carrier=1 and never sends an LACPDU, so the bond sits in AD_STATE_DEFAULTED. e1000e fixes it with no other change. Matches the netdev thread "bonding (IEEE 802.3ad) not working with qemu/virtio". - OVS defaults bonds to active-backup, which does not speak LACP at all — bond_mode=balance-tcp is required. - LACP deadlock: OVS holds members disabled until negotiation while the partner needs carrier before it will send LACPDUs. lacp-fallback-ab breaks it. - LACPDUs are untagged, so a trunk with no native VLAN has nowhere to put them. - --boot cdrom,hd re-runs the ISO on every restart, so every commit+save went to a live system that evaporated. Install now switches the VM to boot hd. - cloud-init on Alpine: users stay locked without lock_passwd:false, one failing runcmd aborts the rest, busybox here has no httpd applet, and start-stop-daemon --exec /usr/bin/python3 matches cloud-init's own python3. - The user-data heredoc is unquoted, so backticks in a COMMENT were executed by the host shell and their output corrupted the YAML. build_seed now validates with yaml.safe_load before building the ISO. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01DMVzWZgiKW2wquf5z8S1yH
2026-08-13 00:42:39 +01:00
#!/bin/bash
# Tear down the lab network simulation.
#
# By default this destroys VMs and networks but KEEPS the downloaded base
# image, so the next bring-up is fast. Pass --purge to remove that too.
#
# Usage: ./labsim-down.sh [--purge] [vlan-id ...]
set -euo pipefail
SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
source "$SCRIPT_DIR/lib.sh"
source "$SCRIPT_DIR/ovs.sh"
PURGE=false
ARGS=()
for a in "$@"; do
case "$a" in
--purge) PURGE=true ;;
*) ARGS+=("$a") ;;
esac
done
selected_vlans "${ARGS[@]+"${ARGS[@]}"}"
for entry in "${SELECTED[@]}"; do
IFS=: read -r vid name prefix _r <<<"$entry"
vm="$(vm_name "$vid" "$name")"
if virsh_q dominfo "$vm" >/dev/null 2>&1; then
log "destroying VM $vm"
virsh_q destroy "$vm" >/dev/null 2>&1 || true
virsh_q undefine "$vm" --nvram >/dev/null 2>&1 || virsh_q undefine "$vm" >/dev/null 2>&1 || true
fi
sudo rm -f "$IMG_DIR/${vm}.qcow2" "$IMG_DIR/${vm}-seed.iso"
done
# Legacy per-VLAN Linux-bridge networks from before the OVS migration. If
# these survive they keep a duplicate <prefix>.2/24 on a dead bridge, and the
# kernel may prefer that route over the OVS host leg — which looks exactly
# like "the VM is unreachable" while ping -I hostvN works fine.
for entry in "${SELECTED[@]}"; do
IFS=: read -r vid _n _p _r <<<"$entry"
legacy="labsim-vlan${vid}"
if virsh_q net-info "$legacy" >/dev/null 2>&1; then
log "removing legacy network $legacy"
virsh_q net-destroy "$legacy" >/dev/null 2>&1 || true
virsh_q net-undefine "$legacy" >/dev/null 2>&1 || true
fi
done
log "removing OVS fabric"
ovs_down
if [ "$PURGE" = true ]; then
log "purging base image $BASE_IMAGE"
sudo rm -f "$BASE_IMAGE"
sudo rmdir "$IMG_DIR" 2>/dev/null || true
fi
log "environment is DOWN"