Merge pull request 'fix(obs): the deploy notification was inhibited before it could send' (#26) from fix/flux-deploy-notification-inhibited into main

Reviewed-on: #26
Reviewed-by: Keith Jackson <[email protected]>

decisions/2026-09-30-flux-deploy-notification-inhibited.md

@@ -0,0 +1,95 @@
+---
+date: 2026-09-30
+branch: fix/flux-deploy-notification-inhibited
+title: The deploy notification routed correctly and was then inhibited before sending — `severity: info` is a suppressed class in kube-prometheus-stack
+---
+
+## What changed
+
+`FluxRolloutInProgress` (shipped hours earlier in PR #25) fired correctly on the very first real
+deploy and **its mail was suppressed before Alertmanager sent it**. One label changed:
+
+- `platform/monitoring/alerts.yaml` — `FluxRolloutInProgress` now carries `notification: deploy` and
+  **no `severity` label at all**, where it previously carried `severity: info`.
+- `platform/monitoring/kube-prometheus-stack.yaml` — the deploy route matches
+  `notification = "deploy"` instead of `severity = "info"`. Receiver, subject and grouping unchanged.
+- `platform/monitoring/tests/flux-rollout.test.yaml` — the three `FluxRolloutInProgress` `exp_labels`
+  blocks updated. `FluxRolloutStuck` keeps `severity: warning` and is unaffected.
+
+**The mechanism, measured rather than reasoned about.** kube-prometheus-stack's `general.rules`
+ships:
+
+    InfoInhibitor:
+      group by (namespace) (ALERTS{severity="info"} == 1)
+        unless on (namespace) group by (namespace)
+          (ALERTS{alertname!="InfoInhibitor", alertstate="firing", severity=~"warning|critical"} == 1)
+
+which fires for any namespace holding a firing `severity="info"` alert **and nothing else wrong in
+it**. The chart's third `inhibit_rule` then drops exactly that alert:
+
+    source_matchers: [alertname="InfoInhibitor"]
+    target_matchers: [severity="info"]
+    equal:           [namespace]
+
+For a deploy notification this is the worst possible interaction, because the suppressed case is the
+*only* case that matters: on a healthy rollout of a healthy cluster, `flux-system` holds no warning
+or critical alert, so `InfoInhibitor` fires and the deploy mail is inhibited. It would have been
+delivered only when something else in `flux-system` was already broken.
+
+Upstream's intent is explicit and reasonable — `severity: info` means "only worth showing next to a
+real problem". A deploy notice is not that, so it must not claim that severity. `notification` is a
+label **no** `inhibit_rule` in the chart targets (all three match on severity values), and dropping
+`severity` also stops `InfoInhibitor` firing for `flux-system` at all rather than merely working
+around it. Both files carry the full reasoning inline, and `alerts.yaml`'s design header now names
+the severity label as a third thing that must not regress — "do not tidy this by adding a severity"
+— because the next reader's instinct will be to add one back.
+
+## What I verified
+
+Against live prod, after PR #25 merged as `64c72fd` and Flux converged:
+
+- **The metrics work.** `kube_flux_kustomization_info` 16, `kube_flux_kustomization_suspended` 16,
+  `kube_flux_gitrepository_info` 1 = **33 series, exactly as designed**. The `revision` label IS
+  populated (`main@sha1:296d6d3…` / `…64c72fd…`), so the `status.lastAppliedRevision` /
+  `status.artifact.revision` paths are correct — previously UNVERIFIED.
+- **The `podAnnotations` roll mechanism works.** The KSM pod carries
+  `homelab.keithjackson.dev/crs-config-rollout: 1` and is a new pod
+  (`…-7b56d98f46-56n8j`, replacing the 2026-09-19 one), so the config-only-change trap was
+  genuinely closed rather than merely documented.
+- **The rule works, in both directions.** It fired for **12** lagging Kustomizations while 4 had
+  converged (`count by (revision)` → 12 old / 4 new), each alert carrying its own `name` and
+  `revision`; then the rollout converged (`count(count by (revision) (…))` → **1**) and the alert
+  **cleared**. Firing and self-clearing are both confirmed on real data, which is the completion
+  notification's whole mechanism.
+- **The routing works.** `amtool config routes` shows
+  `{notification="deploy"} → receiver: email-deploy` under the default route, and
+  `amtool config routes test notification=deploy` returns `email-deploy`.
+- **The inhibition was real.** `InfoInhibitor` went active `2026-09-30T04:58:48Z` — the same moment
+  the alert began firing — and `amtool alert query` showed **no** `FluxRolloutInProgress` in
+  Alertmanager, active or `--inhibited`. `alertmanager_notifications_failed_total{integration=email}`
+  is 0 for every reason, so nothing failed to send; it was never dispatched.
+- promtool: **SUCCESS**, 53 rules, 6 scenarios, promtool 3.14.0 in the pinned toolbox.
+
+## What I did NOT verify
+
+- **No deploy mail has been observed in the inbox — this fix is UNVERIFIED end to end.** The
+  suppression was proven (nothing in Alertmanager, zero send failures) and the routing was proven
+  (`amtool config routes test` → `email-deploy`), but the delivered message is not. It can only be
+  proven by merging this and watching the next commit produce `[FLUX] applying` and then
+  `[FLUX] applied`. Same structural gap as PR #25, one layer further along.
+- **Whether the single email during the window was ours.**
+  `alertmanager_notifications_total{integration="email"}` went 226 → 227 while other alerts
+  (`Watchdog`, `CNPGPrimariesCoLocated`) were also active, and that counter carries no receiver
+  label, so the increment cannot be attributed. I am NOT claiming our mail was or was not sent — the
+  attribution is genuinely unavailable from this metric.
+- **Whether `InfoInhibitor` interacts with `FluxRolloutStuck`.** Stuck is `severity: warning`;
+  inhibit_rule 1 (`critical` → `warning|info`) requires an equal `alertname`, so it should not
+  apply — reasoned, not measured. Worth confirming the first time a rollout genuinely hangs.
+- **The `[FLUX] applying|applied` subject template** is still untested; `.Status` is assumed to be
+  `firing`/`resolved` in the notification template data.
+- **`required_approvals` disagreement, unresolved and not mine to settle.** Live branch protection
+  reads `required_approvals: 1`, while the `ci/gate.sh` comment introduced by PR #17 describes the
+  model as `required_approvals: 0` ("the gate is the approver"). `ci/gitea-settings.sh` may report
+  this as drift against `infra/gitea/expected-branch-protection.json`. Flagged only.
+- **The drift loop is still unexplained.** Five Kustomizations re-applying the same object every
+  10 minutes (event counts ~2500) — untouched, cause unknown, still deserves its own branch.

platform/monitoring/alerts.yaml

@@ -839,6 +839,14 @@ spec:
         # that has never applied anything — or a GitRepository with no artifact yet — publishes the
         # series with no `revision` label. Without the matcher those group together under the empty
         # string and compare EQUAL, i.e. a never-applied Kustomization would read as converged.
+        #
+        # A THIRD THING THAT MUST NOT REGRESS — THE SEVERITY LABEL. These alerts are delivered
+        # because of the labels they do NOT carry as much as the ones they do. Do not "tidy" this
+        # pair by giving FluxRolloutInProgress a `severity`, and never `severity: info`: the chart's
+        # InfoInhibitor rule plus its `severity="info"` inhibit_rule suppress an info alert whenever
+        # it is the only thing firing in its namespace, which is every healthy deploy. Measured on
+        # prod 2026-09-30 — the alert fired correctly for 12 Kustomizations, resolved correctly, and
+        # was inhibited in between. The full reasoning is on the `notification: deploy` label below.
         # ===================================================================================
         - alert: FluxRolloutInProgress
           expr: |
@@ -857,7 +865,31 @@ spec:
           # `flux reconcile`, a change touching one Kustomization), and a deploy notification that
           # only sometimes arrives is worse than no notification at all.
           labels:
-            severity: info    # -> the email-deploy Alertmanager route; subject "[FLUX] applying/applied"
+            # ROUTED BY `notification`, AND DELIBERATELY CARRYING NO `severity` (fixed 2026-09-30).
+            # This alert originally used `severity: info`. That was WRONG, and wrong in the silent
+            # direction — measured on prod within minutes of the first real deploy.
+            # kube-prometheus-stack ships `general.rules` -> InfoInhibitor:
+            #     group by (namespace) (ALERTS{severity="info"} == 1)
+            #       unless on (namespace) group by (namespace)
+            #         (ALERTS{alertname!="InfoInhibitor", alertstate="firing", severity=~"warning|critical"} == 1)
+            # which fires for any namespace that has a firing info alert AND NOTHING ELSE WRONG in
+            # it; paired with the chart's inhibit_rule
+            #     source_matchers: [alertname="InfoInhibitor"]
+            #     target_matchers: [severity="info"]
+            #     equal: [namespace]
+            # the effect is that an info alert is suppressed EXACTLY WHEN it is the only thing
+            # happening in its namespace. For a deploy notification that is the only case that
+            # matters: on a healthy rollout of a healthy cluster, flux-system has no warning or
+            # critical alert, so InfoInhibitor fired and this alert never reached the receiver.
+            # Verified live: InfoInhibitor went active 2026-09-30T04:58:48Z, the same moment this
+            # alert began firing for 12 Kustomizations.
+            # Upstream's intent is explicit — `severity: info` means "only worth showing next to a
+            # real problem". A deploy notice is not that, so it must not claim that severity.
+            # `notification` is a label no inhibit_rule in the chart targets (all three match on
+            # severity values), and omitting `severity` also stops InfoInhibitor firing for
+            # flux-system at all. Route: platform/monitoring/kube-prometheus-stack.yaml matches
+            # `notification = "deploy"` -> the email-deploy receiver, subject "[FLUX] applying|applied".
+            notification: deploy
           annotations:
             summary: "Flux is applying a new revision — {{ $labels.name }} is behind main"
             description: "Kustomization {{ $labels.namespace }}/{{ $labels.name }} has applied {{ $labels.revision }}, which is not the revision the flux-system GitRepository has fetched from main. THIS MAIL MEANS A GIT CHANGE STARTED ROLLING OUT; the RESOLVED mail for this same alert means every Kustomization reached the new revision and the rollout is complete."

platform/monitoring/kube-prometheus-stack.yaml

@@ -139,11 +139,19 @@ spec:
             #
             # A DEDICATED ROUTE, because the default receiver is `email-warning`: without it a
             # routine deploy arrives subject-lined "[WARNING]" and becomes indistinguishable from a
-            # real platform fault, which is how alert mail stops being read at all. `severity: info`
-            # is used by NO other rule in this repo (grepped 2026-09-29: zero matches), so this
-            # route claims exactly the deploy notices and nothing else. Keep it that way — giving a
-            # genuine fault severity: info would silently route it here and re-label it a deploy.
-            - matchers: ['severity = "info"']
+            # real platform fault, which is how alert mail stops being read at all.
+            #
+            # MATCHES `notification`, NOT `severity` (corrected 2026-09-30). This route first read
+            # `severity = "info"`, which routed correctly and then had the mail SUPPRESSED before it
+            # was sent: the chart's own InfoInhibitor rule fires for any namespace holding a firing
+            # info alert with no warning/critical beside it, and its inhibit_rule
+            # (source alertname="InfoInhibitor" -> target severity="info", equal [namespace]) drops
+            # exactly that alert. A healthy deploy in a healthy flux-system is precisely that case,
+            # so the notification was inhibited on every occasion it was wanted. Measured live on
+            # prod 2026-09-30: InfoInhibitor went active at 04:58:48Z as the alert began firing.
+            # Routing on a non-severity label sidesteps all three of the chart's inhibit_rules,
+            # which match on severity values only. See the label's own comment in alerts.yaml.
+            - matchers: ['notification = "deploy"']
               receiver: email-deploy
               # One mail per ROLLOUT, not per Kustomization: the alert fires once per lagging
               # Kustomization (16 possible), and grouping on alertname alone collapses them into a

platform/monitoring/tests/flux-rollout.test.yaml

@@ -89,7 +89,7 @@ tests:
         alertname: FluxRolloutInProgress
         exp_alerts:
           - exp_labels:
-              severity: info
+              notification: deploy
               job: kube-state-metrics
               namespace: flux-system
               name: platform
@@ -148,7 +148,7 @@ tests:
         alertname: FluxRolloutInProgress
         exp_alerts:
           - exp_labels:
-              severity: info
+              notification: deploy
               job: kube-state-metrics
               namespace: flux-system
               name: platform
@@ -229,7 +229,7 @@ tests:
         alertname: FluxRolloutInProgress
         exp_alerts:
           - exp_labels:
-              severity: info
+              notification: deploy
               job: kube-state-metrics
               namespace: flux-system
               name: conformance