Unit testing

README.md

@@ -1,35 +1,69 @@
 # function-describe-nodegroups
 
 A [Crossplane] Composition Function which reads EKS nodegroup information and
-uses that to create `AWSManagedMachinePool` objects
+uses that to create `MachinePool` anbd `AWSManagedMachinePool` objects.
 
-## How it works
+In order to use this function as part of the [Composition], the composition
+must be written to use pipeline mode. See the documentation on 
+[Composition functions] to better understand how this is integrated
 
-> **Warning**
-> This plugin is requires Crossplane v1.14 which is currently unreleased
-> (due 1st November 2023).
->
-> The example composition is also written for Crossplane v1.14 and will
-> not work on any current MC version.
->
-> To support this, the script [`kind.sh`](./kind.sh) is provided to
-> help you understand how this works by spinning crossplane up inside a
-> kind cluster for local development.
+## Composition integration
 
-In order to use this function as part of the [Composition], the composition
-must be written to use pipeline mode. This is a (currently undocumented)
-mode for compositions.
+This function is placed in the pipeline with a reference to the cluster object
+for that composition.
+
+This should be specified in your composition as follows, setting `clusterRef`
+as appropriate for your composition.
 
 ```yaml
-spec:
-  compositeTypeRef:
-    apiVersion: crossplane.giantswarm.io/v1alpha1
-    kind: CompositeEksImport
-  mode: Pipeline
-  pipeline:
-  - step: collect-cluster
-    ...
-  - step: generate-subnets
-    ...
+    - step: describe-nodegroups
+      functionRef:
+        name: function-describe-nodegroups
+      input:
+        apiVersion: describenodegroups.fn.giantswarm.io
+        kind: Nodegroups
+        metadata:
+          namespace: crossplane
+        spec:
+          clusterRef: eks-cluster
 ```
 
+## How it works
+
+### AWS provider
+
+This function performs a lookup against the AWS API for Nodegroups linked to 
+the clustername referenced in `clusterRef`. It then iterates over that 
+information and populates additional information from secondary lookups to the
+EC2 API and Autoscaling API as appropriate.
+
+Once all information is retrieved, this is then populated into a cluster-api
+provider-aws `AwsManagedMachinePool` object, wrapped inside a 
+`crossplane-contrib/provider-kubernetes` object and returned as a desired
+resource to be reconciled and created by crossplane.
+
+If the nodegroup was created with a `LaunchTemplate` then the function will
+attempt to use that to build the specification for Cluster API. If no launch
+template is found then the function tries to provide all required information
+to Cluster Api so that it can formulate the nodepool(s).
+
+When a launch template is discovered, certain pathways for ClusterAPI are 
+closed off.
+
+- It is not possible to change the instance size when using launch templates
+
+### Azure provider
+
+TBD
+
+### GCP Provider
+
+TBD
+
+## Known Issues
+
+[Crossplane]: https://crossplane.io
+[crossplane-cli]: https://github.com/crossplane/crossplane/releases/tag/v1.14.0-rc.1
+[Composition]: https://docs.crossplane.io/v1.13/concepts/compositions
+[Composition functions]: https://docs.crossplane.io/latest/concepts/compositions/#use-composition-functions
+[RunFunctionRequest]: https://github.com/crossplane/function-sdk-go/blob/a4ada4f934f6f8d3f9018581199c6c71e0343d13/proto/v1beta1/run_function.proto#L36