Mount the rancher secrets engine + seed a service account + roles

Deploys the Rancher token secrets engine into the cluster, mirroring the litellm
and gpg wiring. The plugin is registered separately (config/plugins) and the
deployer policy is granted separately; this mounts and configures the engine.

- Add rancher_secret_backend module (mount + config via the ranchervaultsecret
  provider): rancher_url https://rancher.k8s.syd1.au.unkin.net.
- Add rancher_secret_backend_service_account module: seeds an auto-rotated token
  (90d TTL / 45d rotation), reading the seed token from KV at
  secret_backend/rancher/service_account/<name> (keys: token, token_name).
- Add rancher_secret_backend_role module + a 'ci' role (1h/8h scoped creds).
- Wire config.hcl discovery, module variables, main.tf module blocks, the
  terragrunt inputs, and the rancher provider in root.hcl.

Prereq: populate kv/service/vault/au/syd1/secret_backend/rancher/service_account/admin
with a live Rancher admin token before apply.

modules/vault_cluster/main.tf

@@ -374,6 +374,53 @@ module "gpg_key" {
   depends_on = [module.gpg_secret_backend]
 }
 
+module "rancher_secret_backend" {
+  source = "./modules/rancher_secret_backend"
+
+  for_each = var.rancher_secret_backend
+
+  path                    = each.key
+  plugin                  = each.value.plugin
+  description             = each.value.description
+  rancher_url             = each.value.rancher_url
+  ca_cert                 = each.value.ca_cert
+  tls_skip_verify         = each.value.tls_skip_verify
+  request_timeout_seconds = each.value.request_timeout_seconds
+
+  depends_on = [module.plugin]
+}
+
+module "rancher_secret_backend_service_account" {
+  source = "./modules/rancher_secret_backend_service_account"
+
+  for_each = var.rancher_secret_backend_service_account
+
+  backend         = each.value.backend
+  name            = each.value.name
+  country         = var.country
+  region          = var.region
+  token_ttl       = each.value.token_ttl
+  rotation_period = each.value.rotation_period
+
+  depends_on = [module.rancher_secret_backend]
+}
+
+module "rancher_secret_backend_role" {
+  source = "./modules/rancher_secret_backend_role"
+
+  for_each = var.rancher_secret_backend_role
+
+  backend         = each.value.backend
+  name            = each.value.name
+  service_account = each.value.service_account
+  cluster_name    = each.value.cluster_name
+  description     = each.value.description
+  ttl             = each.value.ttl
+  max_ttl         = each.value.max_ttl
+
+  depends_on = [module.rancher_secret_backend_service_account]
+}
+
 module "vault_policy" {
   source = "./modules/vault_policy"
 

modules/vault_cluster/modules/rancher_secret_backend/main.tf

@@ -0,0 +1,13 @@
+# Mounts the rancher secrets engine and writes its connection config via the
+# ranchervaultsecret provider. The plugin is registered ("imported") in the
+# catalog separately (config/plugins/vault-plugin-secrets-rancher.yaml). Seeded
+# service-account tokens and roles are managed by the sibling modules.
+resource "rancher_secret_backend" "this" {
+  path                    = var.path
+  plugin                  = var.plugin
+  description             = var.description
+  rancher_url             = var.rancher_url
+  ca_cert                 = var.ca_cert
+  tls_skip_verify         = var.tls_skip_verify
+  request_timeout_seconds = var.request_timeout_seconds
+}

modules/vault_cluster/modules/rancher_secret_backend/terraform.tf

@@ -0,0 +1,9 @@
+terraform {
+  required_version = ">= 1.10"
+  required_providers {
+    rancher = {
+      source  = "artifactapi.k8s.syd1.au.unkin.net/terraform-unkin/ranchervaultsecret"
+      version = "0.1.0"
+    }
+  }
+}

modules/vault_cluster/modules/rancher_secret_backend/variables.tf

@@ -0,0 +1,39 @@
+variable "path" {
+  description = "Mount path of the rancher secrets engine (e.g. \"rancher\")"
+  type        = string
+}
+
+variable "plugin" {
+  description = "Registered plugin name to mount (the catalog name = mount type)"
+  type        = string
+  default     = "vault-plugin-secrets-rancher"
+}
+
+variable "description" {
+  description = "Human-friendly description of the mount"
+  type        = string
+  default     = null
+}
+
+variable "rancher_url" {
+  description = "Base URL of the Rancher server (e.g. https://rancher.k8s.syd1.au.unkin.net)"
+  type        = string
+}
+
+variable "ca_cert" {
+  description = "PEM CA certificate that signed the Rancher server's TLS cert (optional; omit to use the system trust store)"
+  type        = string
+  default     = null
+}
+
+variable "tls_skip_verify" {
+  description = "Skip TLS verification of the Rancher server (not recommended)"
+  type        = bool
+  default     = false
+}
+
+variable "request_timeout_seconds" {
+  description = "HTTP timeout in seconds for calls from the plugin to Rancher"
+  type        = number
+  default     = 30
+}

modules/vault_cluster/modules/rancher_secret_backend_role/main.tf

@@ -0,0 +1,11 @@
+# A role that mints short-lived, optionally cluster-scoped rancher tokens from a
+# service account. Reading rancher/creds/<name> produces a lease-bound token.
+resource "rancher_secret_backend_role" "this" {
+  backend         = var.backend
+  name            = var.name
+  service_account = var.service_account
+  cluster_name    = var.cluster_name
+  description     = var.description
+  ttl             = var.ttl
+  max_ttl         = var.max_ttl
+}

modules/vault_cluster/modules/rancher_secret_backend_role/terraform.tf

@@ -0,0 +1,9 @@
+terraform {
+  required_version = ">= 1.10"
+  required_providers {
+    rancher = {
+      source  = "artifactapi.k8s.syd1.au.unkin.net/terraform-unkin/ranchervaultsecret"
+      version = "0.1.0"
+    }
+  }
+}

modules/vault_cluster/modules/rancher_secret_backend_role/variables.tf

@@ -0,0 +1,38 @@
+variable "backend" {
+  description = "Mount path of the rancher secrets engine this role lives on"
+  type        = string
+}
+
+variable "name" {
+  description = "Role name"
+  type        = string
+}
+
+variable "service_account" {
+  description = "Service account (seeded token) used to mint credentials; its user's RBAC is inherited by minted tokens"
+  type        = string
+}
+
+variable "cluster_name" {
+  description = "Downstream cluster to scope minted tokens to (empty = full Rancher-server scope)"
+  type        = string
+  default     = null
+}
+
+variable "description" {
+  description = "Description applied to each minted Rancher token"
+  type        = string
+  default     = null
+}
+
+variable "ttl" {
+  description = "Default lease TTL in seconds for tokens minted from this role"
+  type        = number
+  default     = null
+}
+
+variable "max_ttl" {
+  description = "Maximum lease TTL in seconds for tokens minted from this role"
+  type        = number
+  default     = null
+}

modules/vault_cluster/modules/rancher_secret_backend_service_account/main.tf

@@ -0,0 +1,18 @@
+# Seeds an auto-rotated rancher service-account token. The seed token is
+# sensitive and read from KV, not stored in git:
+#   kv/service/vault/<country>/<region>/secret_backend/<backend>/service_account/<name>
+# Expected keys: token (required), token_name (optional, the ext.cattle.io Token
+# metadata.name so the engine can delete the seed after the first rotation).
+data "vault_kv_secret_v2" "seed" {
+  mount = "kv"
+  name  = "service/vault/${var.country}/${var.region}/secret_backend/${var.backend}/service_account/${var.name}"
+}
+
+resource "rancher_secret_backend_service_account" "this" {
+  backend         = var.backend
+  name            = var.name
+  token           = data.vault_kv_secret_v2.seed.data["token"]
+  token_name      = lookup(data.vault_kv_secret_v2.seed.data, "token_name", null)
+  token_ttl       = var.token_ttl
+  rotation_period = var.rotation_period
+}

modules/vault_cluster/modules/rancher_secret_backend_service_account/terraform.tf

@@ -0,0 +1,13 @@
+terraform {
+  required_version = ">= 1.10"
+  required_providers {
+    vault = {
+      source  = "hashicorp/vault"
+      version = "5.6.0"
+    }
+    rancher = {
+      source  = "artifactapi.k8s.syd1.au.unkin.net/terraform-unkin/ranchervaultsecret"
+      version = "0.1.0"
+    }
+  }
+}

modules/vault_cluster/modules/rancher_secret_backend_service_account/variables.tf

@@ -0,0 +1,31 @@
+variable "backend" {
+  description = "Mount path of the rancher secrets engine this service account lives on"
+  type        = string
+}
+
+variable "name" {
+  description = "Service-account name"
+  type        = string
+}
+
+variable "country" {
+  description = "Country code, used to locate the seed token in KV"
+  type        = string
+}
+
+variable "region" {
+  description = "Region code, used to locate the seed token in KV"
+  type        = string
+}
+
+variable "token_ttl" {
+  description = "Lifetime in seconds requested for each rotated replacement token (default: engine default, 90d)"
+  type        = number
+  default     = null
+}
+
+variable "rotation_period" {
+  description = "Seconds a token is used before rotation (default: engine default, 45d). Must be < token_ttl"
+  type        = number
+  default     = null
+}

modules/vault_cluster/variables.tf

@@ -350,6 +350,44 @@ variable "gpg_key" {
   default = {}
 }
 
+variable "rancher_secret_backend" {
+  description = "Map of rancher token secret engines to create (mount + config)"
+  type = map(object({
+    plugin                  = optional(string, "vault-plugin-secrets-rancher")
+    description             = optional(string)
+    rancher_url             = string
+    ca_cert                 = optional(string)
+    tls_skip_verify         = optional(bool, false)
+    request_timeout_seconds = optional(number, 30)
+  }))
+  default = {}
+}
+
+variable "rancher_secret_backend_service_account" {
+  description = "Map of seeded, auto-rotated rancher service-account tokens (seed token read from KV)"
+  type = map(object({
+    name            = string
+    backend         = string
+    token_ttl       = optional(number)
+    rotation_period = optional(number)
+  }))
+  default = {}
+}
+
+variable "rancher_secret_backend_role" {
+  description = "Map of rancher token-minting roles to create"
+  type = map(object({
+    name            = string
+    backend         = string
+    service_account = string
+    cluster_name    = optional(string)
+    description     = optional(string)
+    ttl             = optional(number)
+    max_ttl         = optional(number)
+  }))
+  default = {}
+}
+
 variable "policy_auth_map" {
   description = "Map of auth mounts -> auth roles -> policy names"
   type        = map(map(list(string)))