Use a more illustrative default example

Emitting a hello world result isn't very useful. Instead, show how to
compose an MR with some fields derived from the XR and some from the
input.

Signed-off-by: Nic Cope <nicc@rk0n.org>

example/composition.yaml

@@ -14,4 +14,4 @@ spec:
     input:
       apiVersion: template.fn.crossplane.io/v1beta1
       kind: Input
-      example: "Hello world"
+      version: v1beta2

function/fn.py

@@ -1,7 +1,7 @@
 """A Crossplane composition function."""
 
 import grpc
-from crossplane.function import logging, response
+from crossplane.function import logging, resource, response
 from crossplane.function.proto.v1 import run_function_pb2 as fnv1
 from crossplane.function.proto.v1 import run_function_pb2_grpc as grpcv1
 
@@ -22,12 +22,18 @@ class FunctionRunner(grpcv1.FunctionRunnerService):
 
         rsp = response.to(req)
 
-        example = ""
-        if "example" in req.input:
-            example = req.input["example"]
+        version = req.input["version"]
+        region = req.observed.composite.resource["spec"]["region"]
 
-        # TODO: Add your function logic here!
-        response.normal(rsp, f"I was run with input {example}!")
-        log.info("I was run!", input=example)
+        resource.update(
+            rsp.desired.resources["bucket"],
+            {
+                "apiVersion": f"s3.aws.upbound.io/{version}",
+                "kind": "Bucket",
+                "spec": {
+                    "forProvider": {"region": region},
+                },
+            },
+        )
 
         return rsp

package/input/template.fn.crossplane.io_inputs.yaml

@@ -24,9 +24,8 @@ spec:
               of an object. Servers should convert recognized schemas to the latest
               internal value, and may reject unrecognized values. More info: https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#resources'
             type: string
-          example:
-            description: Example is an example field. Replace it with whatever input
-              you need. :)
+          version:
+            description: The bucket version to compose (e.g. v1beta2).
             type: string
           kind:
             description: 'Kind is a string value representing the REST resource this
@@ -36,7 +35,7 @@ spec:
           metadata:
             type: object
         required:
-        - example
+        - version
         type: object
     served: true
     storage: true

tests/test_fn.py

@@ -28,17 +28,36 @@ class TestFunctionRunner(unittest.IsolatedAsyncioTestCase):
             TestCase(
                 reason="The function should return the input as a result.",
                 req=fnv1.RunFunctionRequest(
-                    input=resource.dict_to_struct({"example": "Hello, world"})
+                    input=resource.dict_to_struct({"version": "v1beta2"}),
+                    observed=fnv1.State(
+                        composite=fnv1.Resource(
+                            resource=resource.dict_to_struct(
+                                {
+                                    "apiVersion": "example.crossplane.io/v1",
+                                    "kind": "XR",
+                                    "spec": {"region": "us-west-2"},
+                                }
+                            ),
+                        ),
+                    ),
                 ),
                 want=fnv1.RunFunctionResponse(
                     meta=fnv1.ResponseMeta(ttl=durationpb.Duration(seconds=60)),
-                    desired=fnv1.State(),
-                    results=[
-                        fnv1.Result(
-                            severity=fnv1.SEVERITY_NORMAL,
-                            message="I was run with input Hello, world!",
-                        )
-                    ],
+                    desired=fnv1.State(
+                        resources={
+                            "bucket": fnv1.Resource(
+                                resource=resource.dict_to_struct(
+                                    {
+                                        "apiVersion": "s3.aws.upbound.io/v1beta2",
+                                        "kind": "Bucket",
+                                        "spec": {
+                                            "forProvider": {"region": "us-west-2"},
+                                        },
+                                    }
+                                ),
+                            ),
+                        },
+                    ),
                     context=structpb.Struct(),
                 ),
             ),