mikhail-klimko / crossplane-function-loop

Crossplane Function: Loop

What is this?

This is a Crossplane Composition Function.

Composition Functions let you extend Crossplane with new ways to 'do Composition' - i.e. new ways to produce composed resources given a claim or XR. You use Composition Functions instead of the resources array of templates.

This function generates resources through a loop. This functions works with Crossplane v1.14 or later.

Here's an example of a Composition that uses this Function.

---
apiVersion: nopexample.org/v1alpha1
kind: XNopResource
metadata:
  name: test-resource
spec:
  namespaces:
    - dev
    - production
---
apiVersion: apiextensions.crossplane.io/v1
kind: Composition
metadata:
  name: xnopresources.nop.example.org
spec:
  compositeTypeRef:
    apiVersion: nop.example.org/v1alpha1
    kind: XNopResource
  mode: Pipeline
  pipeline:
  - step: loop
    functionRef:
      name: loop
    input:
      valuesXrPath: "spec.namespaces"
      namePrefix: "ns-"
      paths:
        - "spec.forProvider.manifest.metadata.name"
      resources:
        - base:
            apiVersion: kubernetes.crossplane.io/v1alpha1
            kind: Object
            spec:
              forProvider:
                manifest:
                  apiVersion: v1
                  kind: Namespace

The XNopResource is a Composition that defines the namespaces field as an array. The function used in the Composition will iterate through those values and create a resource for each.

The valuesXrPath in the Composition points to the path in the Composition's XR where the field with array of values.

The namePrefix is an optional value that is used to (optionally) add the prefix to the name of the generated resources.

The paths field is an array used to replace the values of the paths in the generated resources.

The output of the resources generated through those examples is as follows.

apiVersion: kubernetes.crossplane.io/v1alpha1
kind: Object
metadata:
  ...
spec:
  forProvider:
    manifest:
      apiVersion: v1
      kind: Namespace
      metadata:
        name: dev
---
apiVersion: kubernetes.crossplane.io/v1alpha1
kind: Object
metadata:
  ...
spec:
  forProvider:
    manifest:
      apiVersion: v1
      kind: Namespace
      metadata:
        name: production

How To Build This?

go generate ./...

export TAG=v0.0.3

docker image build --tag c8n.io/vfarcic/crossplane-function-loop:$TAG .

docker image push c8n.io/vfarcic/crossplane-function-loop:$TAG

yq --inplace ".spec.package = \"c8n.io/vfarcic/crossplane-function-loop:$TAG\"" examples/functions.yaml

How To Test This?

You can try your function out locally using [xrender][https://github.com/crossplane-contrib/xrender]. With xrender you can run a Function pipeline on your laptop.

Run the Function locally:

go run . --insecure --debug

Once your Function is running, in another window you can use xrender.

go install github.com/crossplane-contrib/xrender@latest

xrender examples/xr.yaml examples/composition.yaml examples/functions-dev.yaml