feat(datastore/redis): logical flavour (#360)

* feat(datastore/redis): add reference flavour — passthrough of an existing redis datastore's outputs (no resources)

Adds modules/datastore/redis/reference/1.0, a reference (passthrough)
flavour for the redis intent. It provisions no cloud resource and requires
no providers; it re-exposes the @facets/redis outputs of an existing redis
datastore (resolved into var.instance.spec.source via the
`x-ui-output-type: @facets/redis` spec field) as a separate logical
resource. An optional db_index targets a distinct logical Redis DB on a
shared physical instance and is reflected into the emitted connection_string.

Use case: staging consolidation — a logical cache pointing at a shared
physical instance/db-index.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PKZUrLtUbJS5GuEyRA8Vd5

* refactor(datastore/redis): rename reference flavour to logical

"reference" clashes with Facets' cross-blueprint reference concept.
"logical" better describes the use case: a logical redis datastore
hosted on a shared/existing physical instance (optional db_index),
re-exposing its connection outputs with no resources created.

Renames modules/datastore/redis/reference -> .../logical and updates
the flavor field, titles, and descriptions accordingly.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PKZUrLtUbJS5GuEyRA8Vd5

---------

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: anshulsao

modules/datastore/redis/logical/1.0/facets.yaml

@@ -0,0 +1,64 @@
+intent: redis
+flavor: logical
+version: '1.0'
+clouds:
+- aws
+- gcp
+- azure
+description: Logical — a logical redis datastore hosted on an existing/shared instance
+  (optional db_index); re-exposes its connection outputs (no resources created). Useful
+  for staging consolidation where a logical cache points at a shared physical instance,
+  optionally on a separate logical DB index.
+intentDetails:
+  type: Datastores
+  description: Logical redis datastore hosted on an existing/shared instance (no resources
+    created)
+  displayName: Redis
+  iconUrl: https://raw.githubusercontent.com/Facets-cloud/facets-modules-redesign/main/icons/redis.svg
+spec:
+  title: Redis Logical (Shared Instance)
+  description: Logical — a logical redis datastore hosted on an existing/shared instance
+    (optional db_index); re-exposes its connection outputs (no resources created).
+    Select a source Redis resource whose full outputs are resolved into this resource;
+    optionally target a different logical DB index on the shared instance.
+  type: object
+  x-ui-order:
+  - source
+  - db_index
+  properties:
+    source:
+      type: object
+      title: Source Redis Datastore
+      description: The existing Redis datastore whose outputs this reference re-exposes.
+        Resolves to the selected resource's full outputs.
+      x-ui-output-type: '@facets/redis'
+    db_index:
+      type: number
+      title: Logical DB Index
+      description: Redis logical database index to target on the shared instance. Use
+        a distinct index to separate this logical cache from others sharing the same
+        physical instance.
+      minimum: 0
+      maximum: 15
+      default: 0
+  required:
+  - source
+inputs: {}
+outputs:
+  default:
+    type: '@facets/redis'
+    title: Redis Reference (Passthrough)
+iac:
+  validated_files:
+  - main.tf
+  - variables.tf
+  - locals.tf
+  - outputs.tf
+sample:
+  kind: redis
+  flavor: logical
+  version: '1.0'
+  disabled: true
+  spec:
+    source: {}
+    db_index: 0

modules/datastore/redis/logical/1.0/locals.tf

@@ -0,0 +1,19 @@
+locals {
+  # Full outputs of the selected source @facets/redis datastore, resolved into
+  # var.instance.spec.source via the `x-ui-output-type: @facets/redis` spec field.
+  source_cluster = lookup(lookup(var.instance.spec.source, "interfaces", {}), "cluster", {})
+
+  source_endpoint          = lookup(local.source_cluster, "endpoint", null)
+  source_connection_string = lookup(local.source_cluster, "connection_string", null)
+  source_auth_token        = lookup(local.source_cluster, "auth_token", null)
+  source_port              = lookup(local.source_cluster, "port", null)
+  source_secrets           = lookup(local.source_cluster, "secrets", [])
+
+  db_index = lookup(var.instance.spec, "db_index", 0)
+
+  # Reflect the logical DB index in the connection string. The source
+  # @facets/redis connection_string has the form redis://:<auth>@<host>:<port>
+  # (no DB path), so we append /<db_index> to target the logical DB. If the
+  # source did not expose a connection_string, leave it null.
+  connection_string = local.source_connection_string == null ? null : "${local.source_connection_string}/${local.db_index}"
+}

modules/datastore/redis/logical/1.0/main.tf

@@ -0,0 +1,11 @@
+terraform {
+  required_version = ">= 1.0"
+}
+
+# Reference (passthrough) flavour.
+#
+# This module deliberately declares NO resources and requires NO providers.
+# It simply re-exposes the outputs of an existing Redis datastore (resolved
+# into var.instance.spec.source via the `x-ui-output-type: @facets/redis`
+# spec field) as a separate logical resource. See locals.tf / outputs.tf for
+# the passthrough wiring.

modules/datastore/redis/logical/1.0/outputs.tf

@@ -0,0 +1,15 @@
+locals {
+  output_attributes = {}
+
+  # Pure passthrough of the source Redis datastore's @facets/redis interface,
+  # with db_index reflected into the connection_string. No resources are created.
+  output_interfaces = {
+    cluster = {
+      endpoint          = local.source_endpoint
+      connection_string = local.connection_string
+      auth_token        = local.source_auth_token
+      port              = local.source_port
+      secrets           = local.source_secrets
+    }
+  }
+}

modules/datastore/redis/logical/1.0/variables.tf

@@ -0,0 +1,50 @@
+variable "instance" {
+  description = "Logical Redis datastore hosted on an existing/shared instance — re-exposes an existing Redis datastore's outputs without provisioning any resource"
+  type = object({
+    kind    = string
+    flavor  = string
+    version = string
+    spec = object({
+      # Resolved full outputs of the selected source @facets/redis datastore.
+      source = object({
+        attributes = optional(object({}), {})
+        interfaces = optional(object({
+          cluster = optional(object({
+            endpoint          = optional(string)
+            connection_string = optional(string)
+            auth_token        = optional(string)
+            port              = optional(string)
+            secrets           = optional(list(string), [])
+          }), {})
+        }), {})
+      })
+      # Logical Redis DB index to target on the shared instance.
+      db_index = optional(number, 0)
+    })
+  })
+
+  validation {
+    condition     = lookup(var.instance.spec, "db_index", 0) >= 0 && lookup(var.instance.spec, "db_index", 0) <= 15
+    error_message = "db_index must be between 0 and 15"
+  }
+}
+
+variable "instance_name" {
+  description = "The architectural name for the resource as added in the Facets blueprint designer."
+  type        = string
+}
+
+variable "environment" {
+  description = "An object containing details about the environment."
+  type = object({
+    name        = string
+    unique_name = string
+    cloud_tags  = map(string)
+  })
+}
+
+variable "inputs" {
+  description = "A map of inputs requested by the module developer. This reference flavour requires no inputs."
+  type        = object({})
+  default     = {}
+}