From 72e77464c71ce6da32a0ad0ecb3e02f5ac048101 Mon Sep 17 00:00:00 2001
From: Yury Tsarev <yury@upbound.io>
Date: Fri, 7 Oct 2022 00:34:23 +0200
Subject: [PATCH] Example of observe-only workaround experiment

Provides a temporary solution to the observe-only problem using provider-terraform.

See https://github.com/crossplane/crossplane/issues/1722

Signed-off-by: Yury Tsarev <yury@upbound.io>
---
 examples/observe-only-composition/README.md   | 16 ++++++
 .../observe-only-composition/composition.yaml | 57 +++++++++++++++++++
 .../observe-only-composition/definition.yaml  | 32 +++++++++++
 .../observe-only-composition/xsubnet.yaml     |  6 ++
 4 files changed, 111 insertions(+)
 create mode 100644 examples/observe-only-composition/README.md
 create mode 100644 examples/observe-only-composition/composition.yaml
 create mode 100644 examples/observe-only-composition/definition.yaml
 create mode 100644 examples/observe-only-composition/xsubnet.yaml

diff --git a/examples/observe-only-composition/README.md b/examples/observe-only-composition/README.md
new file mode 100644
index 0000000..6f4036f
--- /dev/null
+++ b/examples/observe-only-composition/README.md
@@ -0,0 +1,16 @@
+# Workaround for Observe-Only Resources Functionality
+
+This example Configuration(Composition+XRD) demonstrates a temporary workaround
+for Observe-Only Resources functionality before it is [properly
+implemented](https://github.com/crossplane/crossplane/issues/1722)
+the core Crossplane.
+
+The workaround consists of a `Composition` that provides a mix of provider-terraform
+`Workspace` with the
+[aws_vpc](https://registry.terraform.io/providers/hashicorp/aws/latest/docs/data-sources/vpc)
+**data** resource as Inline module.
+
+It publishes the discovered observe-only `vpcId` to the `XSubnet` XR status.
+
+The `vpcId` from the status is getting eventually consumed by the native `Subnet`
+provider-aws resource which is a part of the same `Composition`.
diff --git a/examples/observe-only-composition/composition.yaml b/examples/observe-only-composition/composition.yaml
new file mode 100644
index 0000000..9962fae
--- /dev/null
+++ b/examples/observe-only-composition/composition.yaml
@@ -0,0 +1,57 @@
+apiVersion: apiextensions.crossplane.io/v1
+kind: Composition
+metadata:
+  name: xsubnets.aws.platformref.upbound.io
+  labels:
+    provider: aws
+spec:
+  compositeTypeRef:
+    apiVersion: aws.platformref.upbound.io/v1alpha1
+    kind: XSubnet
+  resources:
+    - name: observe-only-vpc
+      base:
+        apiVersion: tf.crossplane.io/v1alpha1
+        kind: Workspace
+        metadata:
+          name: observe-only-vpc
+        spec:
+          forProvider:
+            source: Inline
+            module: |
+              data "aws_vpc" "observe_only" {
+                tags = {
+                  Name = var.vpcName
+                }
+              }
+              output "vpc_id" {
+                description = "Observe Only VPC ID"
+                value       = try(data.aws_vpc.observe_only.id, "")
+              }
+              variable "vpcName" {
+                description = "VPC name"
+                type        = string
+              }
+            vars:
+              - key: vpcName
+      patches:
+        - fromFieldPath: spec.vpcName
+          toFieldPath: spec.forProvider.vars[0].value
+        - type: ToCompositeFieldPath
+          fromFieldPath: status.atProvider.outputs.vpc_id
+          toFieldPath: status.share.vpcId
+          policy:
+            fromFieldPath: Optional
+    - name: subnet
+      base:
+        apiVersion: ec2.aws.upbound.io/v1beta1
+        kind: Subnet
+        spec:
+          forProvider:
+            region: eu-central-1
+            cidrBlock: 10.0.0.0/25
+      patches:
+        - fromFieldPath: status.share.vpcId
+          toFieldPath: spec.forProvider.vpcId
+          policy:
+            fromFieldPath: Required
diff --git a/examples/observe-only-composition/definition.yaml b/examples/observe-only-composition/definition.yaml
new file mode 100644
index 0000000..a12029e
--- /dev/null
+++ b/examples/observe-only-composition/definition.yaml
@@ -0,0 +1,32 @@
+apiVersion: apiextensions.crossplane.io/v1
+kind: CompositeResourceDefinition
+metadata:
+  name: xsubnets.aws.platformref.upbound.io
+spec:
+  group: aws.platformref.upbound.io
+  names:
+    kind: XSubnet
+    plural: xsubnets
+  versions:
+  - name: v1alpha1
+    served: true
+    referenceable: true
+    schema:
+      openAPIV3Schema:
+        type: object
+        properties:
+          spec:
+            type: object
+            properties:
+              vpcName:
+                type: string
+            required:
+            - vpcName
+          status:
+            description: A Status represents the observed state
+            properties:
+              share:
+                description: Freeform field containing status information
+                type: object
+                x-kubernetes-preserve-unknown-fields: true
+            type: object
diff --git a/examples/observe-only-composition/xsubnet.yaml b/examples/observe-only-composition/xsubnet.yaml
new file mode 100644
index 0000000..0b4364d
--- /dev/null
+++ b/examples/observe-only-composition/xsubnet.yaml
@@ -0,0 +1,6 @@
+apiVersion: aws.platformref.upbound.io/v1alpha1
+kind: XSubnet
+metadata:
+  name: subnet-with-observe-only-vpc
+spec:
+  vpcName: observeonly