Handle stamps the recorded shard assignment onto a newly created HelmRelease. Every miss is permissive: correctness is restored by the placement controller, the webhook only removes the handoff gap.
(ctx context.Context, req admission.Request)
| 54 | // HelmRelease. Every miss is permissive: correctness is restored by the |
| 55 | // placement controller, the webhook only removes the handoff gap. |
| 56 | func (h *ShardWebhook) Handle(ctx context.Context, req admission.Request) admission.Response { |
| 57 | if req.Operation != admissionv1.Create { |
| 58 | return admission.Allowed("only CREATE is mutated") |
| 59 | } |
| 60 | |
| 61 | obj := &metav1.PartialObjectMetadata{} |
| 62 | if err := json.Unmarshal(req.Object.Raw, obj); err != nil { |
| 63 | return admission.Errored(http.StatusBadRequest, fmt.Errorf("decoding object metadata: %w", err)) |
| 64 | } |
| 65 | // Admission objects may omit metadata.namespace before defaulting. |
| 66 | if obj.Namespace == "" { |
| 67 | obj.Namespace = req.Namespace |
| 68 | } |
| 69 | |
| 70 | tenantNS, ok := TenantNamespaceForHR(obj) |
| 71 | if !ok { |
| 72 | return admission.Allowed("not a tenant HelmRelease") |
| 73 | } |
| 74 | |
| 75 | ns := NamespaceMeta() |
| 76 | if err := h.Reader.Get(ctx, types.NamespacedName{Name: tenantNS}, ns); err != nil { |
| 77 | if apierrors.IsNotFound(err) { |
| 78 | // Rare: the tenant namespace is not created yet (e.g. the parent |
| 79 | // tenant HelmRelease arrives before its chart renders the |
| 80 | // namespace). The placement controller assigns on first sight. |
| 81 | return admission.Allowed("tenant namespace not found, deferring to the placement controller") |
| 82 | } |
| 83 | log.FromContext(ctx).Error(err, "resolving tenant namespace", "tenant", tenantNS) |
| 84 | return admission.Allowed("tenant namespace lookup failed, deferring to the placement controller") |
| 85 | } |
| 86 | |
| 87 | shard := ns.Labels[TenantShardLabel] |
| 88 | if _, ok := ParseShardIndex(shard); !ok { |
| 89 | return admission.Allowed("tenant has no recorded shard assignment yet") |
| 90 | } |
| 91 | |
| 92 | if obj.Labels[ShardKeyLabel] == shard { |
| 93 | return admission.Allowed("already on the assigned shard") |
| 94 | } |
| 95 | |
| 96 | // JSON Patch "add" both creates and overwrites object members. |
| 97 | var op jsonpatch.JsonPatchOperation |
| 98 | if obj.Labels == nil { |
| 99 | op = jsonpatch.NewOperation("add", "/metadata/labels", map[string]string{ShardKeyLabel: shard}) |
| 100 | } else { |
| 101 | op = jsonpatch.NewOperation("add", "/metadata/labels/"+escapeJSONPointer(ShardKeyLabel), shard) |
| 102 | } |
| 103 | return admission.Patched("stamped shard "+shard+" for tenant "+tenantNS, op) |
| 104 | } |
| 105 | |
| 106 | // escapeJSONPointer escapes a JSON pointer path segment (RFC 6901). |
| 107 | func escapeJSONPointer(s string) string { |