composition.yaml

apiVersion: apiextensions.crossplane.io/v1
kind: Composition
metadata:
  name: example-function-to-yaml
spec:
  compositeTypeRef:
    apiVersion: example.crossplane.io/v1beta1
    kind: XR
  mode: Pipeline
  pipeline:
    - step: render-templates
      functionRef:
        name: function-go-templating
      input:
        apiVersion: gotemplating.fn.crossplane.io/v1beta1
        kind: GoTemplate
        source: Inline
        inline:
          template: |
            {{- define "labels" -}}
            some-text: {{.val1}}
            other-text: {{.val2}}
            {{- end }}
            

            ## weird indentation to make it work
            {{- define "labels-metadata" -}}
            some-text: {{.val1}}
                other-text: {{.val2}}
            {{- end }}
            {{- define "labels-matchLabels" -}}
            some-text: {{.val1}}
                  other-text: {{.val2}}
            {{- end }}
            ---
            #include example
            {{$vals:= .observed.composite.resource.spec}}
            apiVersion: apps/v1
            kind: Deployment
            metadata:
              name: nginx-deployment
              annotations:
                gotemplating.fn.crossplane.io/composition-resource-name: test1
              labels:
                {{- include "labels" $vals | nindent 4}}
            spec:
              replicas: 3
              selector:
                matchLabels:
                  {{- include "labels" $vals | nindent 6}}
              template:
                metadata:
                  labels:
                    app: nginx
                spec:
                  containers:
                  - name: nginx
                    image: nginx:1.14.2
                    ports:
                    - containerPort: 80
            ---
            # without include, you must define a template per indentation setting
            apiVersion: apps/v1
            kind: Deployment
            metadata:
              name: nginx-deployment
              annotations:
                gotemplating.fn.crossplane.io/composition-resource-name: test2
              labels:
                {{ template "labels-metadata" $vals}}
            spec:
              replicas: 3
              selector:
                matchLabels:
                  {{ template "labels-matchLabels" $vals }}
              template:
                metadata:
                  labels:
                    app: nginx
                spec:
                  containers:
                  - name: nginx
                    image: nginx:1.14.2
                    ports:
                    - containerPort: 80