132 lines
8.1 KiB
Markdown
132 lines
8.1 KiB
Markdown
# Architecture
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> **Status:** the operator is built through Step 4 (reconciler) of
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> [docs/plans/2026-08-07-1747-proxy-operator.md](plans/2026-08-07-1747-proxy-operator.md).
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> This document currently covers the event/reconcile flow; the components
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> table and the Decisions section arrive with Step 10, and the diagrams
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> below grow as the health engine, lease store, discovery API, and orphan
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> GC land.
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## Event flow: cluster events → reconciler functions
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Which functions run in response to which Kubernetes cluster events, as
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wired in `internal/controller/proxy_controller.go`.
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### 1. How cluster events reach the reconciler
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```text
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KUBERNETES CLUSTER EVENTS (wiring: SetupWithManager,
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───────────────────────── proxy_controller.go)
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Proxy CR created / spec edited / Secret created / updated / deleted
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status patched / delete requested │
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│ │
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watch: For(&crawlv1alpha1.Proxy{}) watch: Watches(&corev1.Secret{}, ...)
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│ │
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│ r.proxiesForSecret(ctx, secret)
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│ │ r.List(Proxies in secret's namespace)
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│ │ keeps those whose
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│ │ spec.cloudInit.secretRef.name matches
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│ ▼
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│ [reconcile.Request per matching Proxy]
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▼ │
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┌─────────────────────────────────────────────────┴──┐
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│ controller-runtime workqueue │◄── RequeueAfter timers
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│ (dedup by namespace/name, rate-limited, │ (from prior reconciles)
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│ MaxConcurrentReconciles: 3) │◄── error backoff retries
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└──────────────────────────┬──────────────────────────┘
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▼
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ProxyReconciler.Reconcile(ctx, req)
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```
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The Secret watch makes *rotating a cloud-init Secret* a first-class event:
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it re-enqueues every Proxy referencing that Secret, which is how secret
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rotation triggers VM replacement even though the Proxy spec is untouched.
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### 2. Inside `Reconcile` — dispatch and the single status write
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```text
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Reconcile(ctx, req)
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│ r.Get(ctx, req.NamespacedName, &p) ── fetch the Proxy (NotFound → done)
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│ base := p.DeepCopy() ── snapshot for the diff
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│ defer patchStatusIfChanged(ctx, base, &p) ──────────────────────────┐
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│ │
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├─ p.DeletionTimestamp set ──► reconcileDelete(ctx, &p) │
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├─ p.Spec.Mode == External ──► reconcileExternal(ctx, &p) │
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└─ otherwise (Managed) ──────► reconcileManaged(ctx, &p) │
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▼
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patchStatusIfChanged (status.go)
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│ p.Status.ObservedGeneration = p.Generation
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│ p.Status.Phase = computePhase(&p)
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│ equality.Semantic.DeepEqual(base, p)?
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└─ changed → r.Status().Patch(...) ◄── the ONLY
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unchanged → no API call status write
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```
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### 3. `reconcileManaged` — the state machine
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```text
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reconcileManaged(ctx, p)
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│
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├─ controllerutil.AddFinalizer? ──► r.Update ──► return {} (watch event re-triggers)
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├─ permanent-failure latch (FindStatusCondition == PermanentError
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│ at this generation) ──► return {} (silent until spec edit)
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├─ r.Providers[p.Spec.Provider] missing ──► setProvisioned(PermanentError) → Failed
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│
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├─ resolveCloudInit(ctx, p) ──► r.Get(Secret) if secretRef (error → CloudInitError + backoff)
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├─ hash := specHash(p, cloudInit) (spechash.go)
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│
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├─ status.providerID == "" ─────────► prov.Create(CreateRequest{Name: NameFromUID(p.UID), ...})
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│ │ setSpecHash → r.Update (annotation)
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│ └ stage providerID + Provisioned=False/Provisioning
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│ ──► RequeueAfter: ProvisioningPoll
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│
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├─ annotation != hash, annotation == "" ──► adopt: setSpecHash → r.Update
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│ ──► RequeueAfter: RequeueNow
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├─ annotation != hash, annotation != "" ──► replaceInstance:
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│ prov.Get ─ NotFound → setSpecHash, clear ID/IP
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│ │ ──► RequeueNow (next pass creates)
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│ └ exists → prov.Delete, Provisioned=False/Replacing
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│ ──► RequeueAfter: DeletionPoll
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│
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└─ annotation == hash ──► prov.Get(providerID)
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├─ ErrNotFound ──► clear ID/IP ──► RequeueNow (next pass creates)
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├─ Provisioning ──► Provisioned=False ──► ProvisioningPoll
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├─ Running ──► status.ip = inst.IP,
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│ Provisioned=True/Created ──► DriftPoll
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└─ Stopped/Termin. ──► prov.Delete (cattle) ──► DeletionPoll
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any provider error ──► providerFailure(p, err) ── provider.Class(err):
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├─ ErrQuotaExceeded ──► condition QuotaExceeded ──► RequeueAfter: QuotaRetry (nil error)
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├─ ErrPermanent ──► condition PermanentError ──► phase Failed, no retry
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└─ ErrTransient ──► return err ──► workqueue exponential backoff
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```
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### 4. `reconcileDelete` and `reconcileExternal`
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```text
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reconcileDelete(ctx, p) reconcileExternal(ctx, p)
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├─ no finalizer ──► return {} │ status.ip = spec.endpoint.host
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├─ providerID == "" ──► RemoveFinalizer │ setProvisioned(True/ExternalEndpoint)
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│ → r.Update → object actually deleted └─ return {} (no finalizer, no
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├─ prov.Get → ErrNotFound ──► RemoveFinalizer provider calls ever;
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│ → r.Update → object actually deleted the health engine —
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└─ exists ──► prov.Delete Step 5 — drives the rest)
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→ Provisioned=False/Deleting
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──► RequeueAfter: DeletionPoll (poll until gone)
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```
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### 5. What provider calls do back in the cluster (kubernetes pod provider)
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```text
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prov.Create ──► buildPod (pure) ──► client.Create(corev1.Pod) ─┐ these cause Pod events,
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prov.Get ──► client.Get(Pod) → phase/IP → InstanceState │ but the operator does NOT
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prov.Delete ──► client.Delete(Pod, tolerate NotFound) │ watch Pods — it observes
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prov.ListByTag ─► client.List(Pods by labels, all namespaces) ─┘ them by polling prov.Get
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on each RequeueAfter tick
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```
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The reconciler never watches provider-side resources (Pods now, GCP VMs
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later). All instance-state observation is poll-based through the
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`Provider` interface, so the same flow works identically for a cloud API
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that has no watch mechanism at all. |