helm-charts/valkey/templates/valkey.networkpolicy.yaml

{{- /*
NetworkPolicy for valkey (Gitea #5).

THIS CHART AND stalwart ARE THE TWO THAT HAD A POLICY BEFORE #5, so the
convention was derived from them rather than imposed on them. What changed here
is the FORM and not a single rule: the reasoning moved out of "#" comments,
which are part of the rendered object and travel into the cluster, into template
comments, which render nothing. ci/run-networkpolicy-test.sh now fails on a
rendered "#", and this file was one of the two that failed it.

TWO THINGS THAT DELIBERATELY DID NOT CHANGE, because they are right and the
convention was written to accommodate them:

1. INGRESS ONLY. This instance opens no outbound connection of its own - no
   replication, no cluster bus - so an egress rule here would constrain nothing
   while making the object look stricter than it is. policyTypes names only
   what there is something to restrict. homeassistant and satisfactory invoke
   the same rule in the other direction, for outbound traffic nobody can
   enumerate.

2. 6379 IS RESTRICTED BY SOURCE, with no probeSources value anywhere in this
   chart - and that combination is only safe because of a detail worth knowing:
   ALL THREE PROBES HERE ARE EXEC PROBES. An exec probe runs inside the
   container through the kubelet's runtime and puts no packet on the network, so
   there is no kubelet traffic to let through and nothing to accommodate. A
   chart with an httpGet or tcpSocket probe on this port could NOT restrict it
   this way - it would need the worker node's IP, which no chart can know, and
   the pod would never become Ready without it. minecraft-server is tight for
   the same reason; every web app in the sweep is not.

So this policy is what the rest of the rollout aims at and mostly cannot reach:
a port that is genuinely closed to everything but the namespaces named below.
*/ -}}
{{- if .Values.networkPolicy.enabled }}
{{- /* networkPolicy.ingress - the policy's INBOUND side, and not the same
       thing as the top-level .Values.ingress (the Ingress object) - both match
       a search for "ingress". */}}
{{- $npIngress := .Values.networkPolicy.ingress | default dict }}
{{- /* NULL-SAFE ON PURPOSE (#99): ambientMesh is an OBJECT, so every read goes
       through a fallback reproducing THIS chart's declared defaults. An
       operator who deletes the object, or writes only "enabled: true", must
       land on the defaults and not in a nil dereference - #136 shipped exactly
       that defect one value away, where the NOTES.txt branch dereferenced
       .networkPolicy.egress directly. */}}
{{- $ambient := $npIngress.ambientMesh | default dict }}
{{- $ambientEnabled := $ambient.enabled }}
{{- $ambientPort := $ambient.port | default 15008 }}
apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:
  name: {{ .Release.Name }}-{{ .Chart.Name }}-networkpolicy
  labels:
    app: {{ .Release.Name }}-{{ .Chart.Name }}-networkpolicy
spec:
  podSelector:
    matchLabels:
      app: {{ .Release.Name }}-{{ .Chart.Name }}-sfs
  policyTypes:
    - Ingress
  ingress:
    {{- /*
    One rule with a list of sources. Note the shape: an empty "from" would allow
    EVERYTHING, so the namespaces are always spelled out - the release's own
    namespace first, then whatever networkPolicy.allowedNamespaces adds. An
    empty "from: []" is worse still, because it allows everything while reading
    as a restriction; ci/run-networkpolicy-test.sh rejects that form outright.
    */}}
    - from:
        - namespaceSelector:
            matchLabels:
              {{- /*
              Set by Kubernetes itself on every namespace (>= 1.21), so this
              needs no labelling work on the target namespaces.
              */}}
              kubernetes.io/metadata.name: {{ .Release.Namespace }}
        {{- range .Values.networkPolicy.allowedNamespaces }}
        - namespaceSelector:
            matchLabels:
              kubernetes.io/metadata.name: {{ . | quote }}
        {{- end }}
      ports:
        - protocol: TCP
          port: 6379
        {{- if $ambientEnabled }}
        {{- /* networkPolicy.ingress.ambientMesh (Gitea #143). 15008/TCP is ztunnel's
               HBONE tunnel, the port every inbound connection arrives on once the
               namespace carries istio.io/dataplane-mode - ambient "does not and will
               never bypass Kubernetes NetworkPolicy enforcement", so without it a pod
               in the mesh is unreachable.

               It is the one port here that is NOT a containerPort of the selected pod
               spec: ztunnel terminates it, not the application. ci/run-networkpolicy-
               test.sh holds a NAMED exception for exactly this number, gated on exactly
               this value, and proves on a second render that it stays the only such
               port and that it is absent while the value is false.

               THE PORT HALF ONLY, and that is not an omission. Elsewhere this switch
               also adds 169.254.7.127/32 as a probe source, because inside the mesh the
               kubelet's probes are redirected away from the worker node's address.
               This chart offers no networkPolicy.probeSources at all, so the rule
               carrying the probe port is never restricted by source - and an
               unrestricted rule needs no probe address. Measured in the render: three
               exec probes, which run inside the container through the kubelet's
               runtime and put no packet on the network at all.
               WHICH RULE IT JOINS:
               the only rule this policy has, the one carrying 6379. That rule is
               ALWAYS restricted to the release's own namespace plus allowedNamespaces,
               so 15008 is restricted with it - and whether ztunnel is reached by those
               peers is the open question of #143. ztunnel runs with its own pod IPs in
               istio-system (measured 2026-10-19: no hostNetwork on the DaemonSet,
               Istio 1.30.6), so if a peer of its own proves necessary it is
               expressible as a namespaceSelector plus podSelector and not as an
               unknowable node CIDR. It cannot be settled before a namespace joins the
               mesh, and none has.
               AN ISTIO CONSTANT, NOT A STANDARD: 15008 is not registered with
               IANA for this, no protocol prescribes it, and Kubernetes knows
               nothing about it - Istio picked it for HBONE and Istio can change
               it. Hence a VALUE with a documented default rather than a literal
               here, so an operator can correct it without a chart release. Read
               for ztunnel 1.30.6. The exception ci/run-networkpolicy-test.sh
               grants is pinned to the number THAT TEST names, plus a check that
               this chart declares the same default - never to whatever the value
               says, because that would let a mistyped port ride in through a
               configurable field (design A of #143).

               NOT MEASURED: that 15008 alone suffices comes from Istio's
               documentation. Measured on this cluster is only which listeners ztunnel
               opens. Provable at the first namespace to join the mesh; none has. */}}
        - protocol: TCP
          port: {{ int $ambientPort }}
        {{- end }}
{{- end }}