为 sandbox 接入 OpenBao External Secrets

infrastructure/openbao/README.md

@@ -51,7 +51,7 @@ few things Terraform must not own.**
 | secrets engine mounts (`kv`, `pki`, `ssh-client-signer`) | the daemon, Raft, TLS files, systemd |
 | PKI role, issuing/CRL URLs, cluster paths, **ACME** | `bao operator init` / unseal (manual, PGP-wrapped) |
 | SSH signing role (`ai-agent`) | **PKI root CA + SSH CA signing key** |
-| OIDC auth *mount* and *role* | OIDC **client secret** (`auth/oidc/config`) |
+| OIDC/Kubernetes auth mount、config 与 role | OIDC **client secret** (`auth/oidc/config`) |
 | all policies | snapshot token + script + systemd timer |
 |  | host-level CA trust distribution (`openbao_ssh_ca_trust`) |
 
@@ -92,6 +92,12 @@ then `VAULT_ADDR`/`VAULT_TOKEN`), mirroring how `smtp-relay/terraform` uses
 native `openbao/openbao` provider is published only to the OpenTofu registry and
 cannot be resolved by the HashiCorp `terraform` CLI.
 
+Sandbox 集群使用独立的 `auth/kubernetes-sandbox`。其 API 地址、公开 Kubernetes CA、
+ESO role 与只读 `kv/k8s/opensandbox-api` policy 全部由 Terraform 管理；CA 位于
+`terraform/certs/sandbox-kubernetes-ca.crt`。集群重建并轮换 CA 后，先更新该文件并
+apply，再让 Flux 恢复 ESO reconciliation。该 backend 不保存 reviewer JWT，而是使用
+ESO 的短期登录 JWT 执行 TokenReview。
+
 ## DNS
 
 `bao.ad.ddupan.top` is an **internal-only** name — not a public Cloudflare record and

infrastructure/openbao/terraform/auth.tf

@@ -59,3 +59,33 @@ resource "vault_kubernetes_auth_backend_role" "external_secrets" {
   # in a long TTL and every extra hour is a longer-lived credential in memory.
   token_ttl = 3600
 }
+
+# A Kubernetes auth mount can validate identities from only the API server it is
+# configured against. The sandbox cluster therefore cannot reuse auth/kubernetes,
+# whose TokenReview endpoint belongs to homelab.
+resource "vault_auth_backend" "sandbox_kubernetes" {
+  type = "kubernetes"
+  path = "kubernetes-sandbox"
+}
+
+resource "vault_kubernetes_auth_backend_config" "sandbox" {
+  backend              = vault_auth_backend.sandbox_kubernetes.path
+  kubernetes_host      = "https://10.60.0.13:6443"
+  kubernetes_ca_cert   = file("${path.module}/certs/sandbox-kubernetes-ca.crt")
+  disable_local_ca_jwt = true
+
+  # Deliberately omit token_reviewer_jwt. OpenBao uses the login JWT for
+  # TokenReview; the sandbox external-secrets ServiceAccount is bound only to
+  # system:auth-delegator and all issued JWTs remain short-lived.
+}
+
+resource "vault_kubernetes_auth_backend_role" "sandbox_external_secrets" {
+  backend   = vault_auth_backend.sandbox_kubernetes.path
+  role_name = "external-secrets"
+
+  bound_service_account_names      = ["external-secrets"]
+  bound_service_account_namespaces = ["external-secrets"]
+
+  token_policies = [vault_policy.sandbox_external_secrets.name]
+  token_ttl      = 3600
+}

infrastructure/openbao/terraform/certs/sandbox-kubernetes-ca.crt

@@ -0,0 +1,10 @@
+-----BEGIN CERTIFICATE-----
+MIIBdjCCAR2gAwIBAgIBADAKBggqhkjOPQQDAjAjMSEwHwYDVQQDDBhrM3Mtc2Vy
+dmVyLWNhQDE3ODk2NTI4NTcwHhcNMjYwOTE3MTI0NzM3WhcNMzYwOTE0MTI0NzM3
+WjAjMSEwHwYDVQQDDBhrM3Mtc2VydmVyLWNhQDE3ODk2NTI4NTcwWTATBgcqhkjO
+PQIBBggqhkjOPQMBBwNCAAR4SbqzTXZnlZdUPz7viN6+dYbB1Maw44Qiepn9r5XG
+sOzkYkN8t1aG3Ugo8TqQ3xJaKkM89n1Rluj0vbOhiNajo0IwQDAOBgNVHQ8BAf8E
+BAMCAqQwDwYDVR0TAQH/BAUwAwEB/zAdBgNVHQ4EFgQUyLSGoKAKAJuiniuRdBLG
+XYaDQC8wCgYIKoZIzj0EAwIDRwAwRAIgFkVzyUZexk/ynnxBEOg+3foJv3WKqAei
+hTSRjO1gL0UCIFbBKR7BMrJJAgW3DJFeeBM+b+tTg93jNx55qZACbFOL
+-----END CERTIFICATE-----

infrastructure/openbao/terraform/policies.tf

@@ -35,3 +35,10 @@ resource "vault_policy" "external_secrets" {
   name   = "external-secrets"
   policy = file("${path.module}/policies/external-secrets.hcl")
 }
+
+# The sandbox cluster has its own Kubernetes auth backend and a deliberately
+# narrower KV view than the homelab ESO instance.
+resource "vault_policy" "sandbox_external_secrets" {
+  name   = "sandbox-external-secrets"
+  policy = file("${path.module}/policies/sandbox-external-secrets.hcl")
+}

infrastructure/openbao/terraform/policies/sandbox-external-secrets.hcl

@@ -0,0 +1,9 @@
+# Read only the shared OpenSandbox control-plane API key. The same Bao object is
+# consumed by the server in sandbox and, later, by the scheduler in homelab.
+path "kv/data/k8s/opensandbox-api" {
+  capabilities = ["read"]
+}
+
+path "kv/metadata/k8s/opensandbox-api" {
+  capabilities = ["read"]
+}