home-network-k3s-impl/conformance/tests/l2-behavioral/egress-default-path/chainsaw-test.yaml

# =============================================================================
# L2 BEHAVIORAL — the default egress path is the WAN; the VPN is opt-in  (R-NET-04)  [RUNNABLE]
# Catalog: docs/14 L2 row ("real runtime behavior, probes against a cluster")
# Spec:    docs/00 R-NET-04 ("The platform MUST support **multiple egress paths** selected by
#          routing rules ... realized as two paths — the local `internet` path and the
#          in-cluster `vpn` path").
#          docs/03 §"Egress routing: two paths, one physical WAN": "the `internet` path is
#          simply the default route out".
#          docs/03 §"VPN egress model": "**Default is the WAN; the VPN is strictly opt-in.**
#          Every pod — and the nodes themselves — egress the local/private WAN by default and
#          **never** the VPN. Only services labeled `egress-class=vpn` are steered to the
#          tunnel"; and the tunnel "is **split-tunnel**: ... only what Cilium points at `tun0`
#          uses the VPN."
#
# WHAT THIS PROVES THAT tests/l2-behavioral/egress-class DOES NOT
# --------------------------------------------------------------
# That test (R-NET-05/07) compares two LABELLED pods — `internet` vs `vpn` — and shows their
# public IPs differ, then flips a label. Both of its pods declared a class, so it says nothing
# about the case R-NET-04 actually turns on: a pod that NO routing rule selects. This test adds
# that pod, and asserts the two claims that make a rule-selected path set complete:
#
#   TOTALITY   — an UNLABELLED pod egresses the WAN, i.e. the same public IP as the
#                explicitly-`internet` pod. Absence of a matching rule IS a path, and it is
#                the local one. If the steering rule ever widened (an empty selector, a
#                matchExpression, a second rule), this pod's IP would move to the tunnel and
#                this assertion is what would notice.
#   COEXISTENCE — the WAN path and the VPN path are live AT THE SAME TIME, observed in one
#                pass: three pods, two distinct public IPs. "Multiple egress paths" is a
#                simultaneity claim, not a claim that one switch has two positions.
#   PER-DESTINATION SELECTION — the vpn-class pod still reaches an in-cluster/RFC1918
#                destination over the LOCAL path while its public traffic is tunnelled. The
#                tunnel is destination-scoped (excludedCIDRs), not a default route, so ONE pod
#                uses BOTH paths at once.
#
# ENVIRONMENT-AGNOSTIC (R-ENV-02): no address, hostname or range appears. Every assertion is a
# RELATION between observed values (equal / not-equal), so it holds against dev and prod alike
# and survives the WAN or the VPN provider rotating addresses.
#
# GIVEN one unlabelled, one `internet`-class and one `vpn`-class pod — the same workload three
#       times, differing only in the class they declare (or do not),
# WHEN  each asks an external echo for the public IP it egressed from, and the vpn-class pod
#       also resolves a name through the in-cluster resolver,
# THEN  the unlabelled pod's public IP EQUALS the internet-class pod's (the default route out
#       is the WAN, and the VPN is strictly opt-in);
# AND   the vpn-class pod's public IP DIFFERS from both (a second, simultaneously-live path);
# AND   the vpn-class pod still resolves in-cluster (its private-destination traffic was not
#       swallowed by the tunnel), so the same pod is using both paths at once.
#
# WHAT THIS DOES *NOT* PROVE (honest gaps — do not read this test as claiming them):
#   - THAT NO OTHER RULE EXISTS. Three pods cannot enumerate a rule set. That exactly one
#     steering rule is authored, that it selects only the vpn class, that no `ip rule` is
#     unscoped and no nftables DROP unqualified is the L0 half, in
#     tests/l0-static/egress-paths-selected-by-rules (same requirement label).
#   - WHICH INTERFACE the packets left by. The observation is the public IP an external echo
#     reports; it distinguishes the paths without naming them. Asserting "out tun0" would need
#     host-level datapath inspection (Hubble/tcpdump on the gateway node), which no test in
#     this suite does.
#   - THE KILL-SWITCH. Tunnel-down behaviour is R-NET-06's, at L3 (vpn-killswitch): `vpn`
#     fails closed. Its mirror — that `internet` is never blackholed — is asserted statically
#     by the L0 half, not here.
#   - NODE traffic. docs/03 also says "the nodes themselves" egress the WAN by default. That
#     is a host-level fact this test cannot see from a pod.
#   - EXTERNAL DEPENDENCY, stated plainly: the public-IP echo (api.ipify.org) is off-cluster,
#     so a WAN outage or the echo being down fails this test. That is the same dependency
#     tests/l2-behavioral/egress-class already carries; the alternative — trusting the
#     cluster's own account of which path it used — would not be a behavioural test at all.
#
# CLEANUP: chainsaw deletes the per-test namespace (all three pods with it). Nothing outside
# that namespace is created or changed — no label on a platform object, no policy edit.
# =============================================================================
apiVersion: chainsaw.kyverno.io/v1alpha1
kind: Test
metadata:
  name: egress-default-path
  labels:
    conformance.home.k3s/R-NET-04: "true"
  annotations:
    conformance.home.k3s/requirements: "R-NET-04"
    conformance.home.k3s/layer: "L2"
    conformance.home.k3s/safety-critical: "false"
    conformance.home.k3s/executable: "true"
    conformance.home.k3s/intent: >-
      Given an unlabelled, an internet-class and a vpn-class pod, when each observes the public
      IP it egressed from, then the unlabelled pod's IP equals the internet-class pod's (the
      default route out is the WAN, the VPN is opt-in) while the vpn-class pod's differs — two
      paths live at once — and the vpn-class pod still reaches in-cluster destinations over the
      local path, so one pod uses both paths simultaneously.
spec:
  timeouts:
    apply: 60s
    assert: 2m
    exec: 3m
  steps:
    # -----------------------------------------------------------------------------------
    - name: given-three-pods-differing-only-in-their-declared-egress-class
      try:
        - apply:
            file: fixtures/three-egress-pods.yaml
        # Bare pods (restartPolicy: Never) — Ready == Running here.
        - assert:
            resource:
              apiVersion: v1
              kind: Pod
              metadata: { name: egress-unlabelled }
              status: { phase: Running }
        - assert:
            resource:
              apiVersion: v1
              kind: Pod
              metadata: { name: egress-internet }
              status: { phase: Running }
        - assert:
            resource:
              apiVersion: v1
              kind: Pod
              metadata: { name: egress-vpn }
              status: { phase: Running }
    # -----------------------------------------------------------------------------------
    - name: then-the-unlabelled-pod-takes-the-wan-and-the-vpn-path-is-live-too
      try:
        - script:
            content: |
              set -eu
              ns="$NAMESPACE"
              get_ip() {
                # Echo the pod's observed public IP, or empty on failure.
                kubectl -n "$ns" exec "$1" -c curl -- \
                  curl -fsS --max-time 10 https://api.ipify.org 2>/dev/null || true
              }

              # Poll until all three answer AND the vpn class has diverged from the WAN:
              # Cilium may still be programming the egress datapath just after the pods go
              # Ready. Bounded by the loop, never a bare sleep-and-hope.
              none="" inet="" vpn=""
              for i in $(seq 1 12); do
                [ -n "$none" ] || none="$(get_ip egress-unlabelled)"
                [ -n "$inet" ] || inet="$(get_ip egress-internet)"
                [ -n "$vpn" ]  || vpn="$(get_ip egress-vpn)"
                if [ -n "$none" ] && [ -n "$inet" ] && [ -n "$vpn" ]; then
                  [ "$vpn" != "$inet" ] && break
                  # Steering may not have converged; re-read the vpn pod only.
                  vpn=""
                fi
                sleep 5
              done
              echo "unlabelled_ip=$none internet_ip=$inet vpn_ip=$vpn"

              [ -n "$none" ] || { echo "FAIL: the UNLABELLED pod never returned a public IP — a pod that declares no egress class must still reach the internet over the default WAN path (docs/03: 'the internet path is simply the default route out'); no path at all means the default was blackholed or steered into a dead tunnel" >&2; exit 1; }
              [ -n "$inet" ] || { echo "FAIL: the internet-class pod never returned a public IP — the declared default path is down, so no comparison is possible" >&2; exit 1; }
              [ -n "$vpn" ]  || { echo "FAIL: the vpn-class pod never returned a public IP — the second egress path is not carrying traffic, so the platform is not offering MULTIPLE paths (R-NET-04)" >&2; exit 1; }

              # TOTALITY: no rule selects the unlabelled pod, so it must land on the WAN —
              # the same WAN the explicitly-internet pod uses.
              if [ "$none" != "$inet" ]; then
                echo "FAIL: the UNLABELLED pod egressed $none but the internet-class pod egressed $inet. They must be the same path: docs/03 — 'Default is the WAN; the VPN is strictly opt-in. Every pod ... egress the local/private WAN by default and never the VPN.' A different IP means some rule is selecting a pod that never opted in." >&2
                exit 1
              fi
              # COEXISTENCE: and the vpn path is a genuinely different path, live right now.
              if [ "$vpn" = "$inet" ]; then
                echo "FAIL: the vpn-class pod egressed the same public IP as the WAN ($vpn) — there is only ONE live egress path, so 'multiple egress paths selected by routing rules' (R-NET-04) does not hold" >&2
                exit 1
              fi
              echo "EGRESS_DEFAULT_PATH_IS_WAN_OK"
            check:
              (contains($stdout, 'EGRESS_DEFAULT_PATH_IS_WAN_OK')): true
    # -----------------------------------------------------------------------------------
    - name: then-the-vpn-class-pod-still-reaches-private-destinations-locally
      try:
        - script:
            # PER-DESTINATION SELECTION. The steering rule tunnels 0.0.0.0/0 MINUS all
            # RFC1918 space, so a vpn-class pod's private-destination traffic must stay on the
            # local datapath. The cluster resolver is an in-cluster (RFC1918) address reached
            # from the pod's own /etc/resolv.conf — no literal is written here — so a
            # successful lookup from the vpn-class pod proves the tunnel did not swallow its
            # local traffic, i.e. ONE pod is using BOTH paths at the same time.
            content: |
              set -eu
              ns="$NAMESPACE"
              resolver="$(kubectl -n "$ns" exec egress-vpn -c curl -- \
                sh -c 'awk "/^nameserver/{print \$2; exit}" /etc/resolv.conf' 2>/dev/null || true)"
              [ -n "$resolver" ] || { echo "FAIL: the vpn-class pod has no nameserver in /etc/resolv.conf, so its local-path reachability cannot be observed" >&2; exit 1; }
              echo "vpn_pod_resolver=$resolver (in-cluster, RFC1918 — excluded from the tunnel)"

              # A cluster-internal name, resolvable only by the in-cluster resolver: reaching
              # it proves the private-destination path works from a vpn-class pod.
              out=""
              for i in $(seq 1 6); do
                out="$(kubectl -n "$ns" exec egress-vpn -c curl -- \
                  nslookup kubernetes.default.svc.cluster.local 2>/dev/null || true)"
                case "$out" in *"Address"*) break ;; esac
                sleep 5
              done
              case "$out" in
                *Address*) : ;;
                *) echo "FAIL: the vpn-class pod could not resolve kubernetes.default.svc.cluster.local via its in-cluster resolver ($resolver). Its RFC1918 traffic is being steered into the tunnel (or blackholed) instead of taking the local path — the two paths are not coexisting per destination, and the tunnel is behaving as a default route (docs/03: split-tunnel, 'only what Cilium points at tun0 uses the VPN')" >&2; exit 1 ;;
              esac
              echo "EGRESS_PATHS_COEXIST_PER_DESTINATION_OK"
            check:
              (contains($stdout, 'EGRESS_PATHS_COEXIST_PER_DESTINATION_OK')): true