Support loading crossplane beta render inputs from stdin

[negz]

Description of your changes

This uses the standard convention of a file named "-" meaning "read this file from stdin". The XR and Composition are assumed to be single YAML files, while functions and observed resources could be a stream.

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• Added or updated unit tests.
• Added or updated e2e tests.
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[phisco]

Sounds reasonable to me, we should probably error if more than one input is "-" to avoid hanging indefinitely.

[jbw976]

Looks good to me @negz, agreed with @phisco's idea to verify that no more than 1 argument is -.

[jbw976]

in the previous code, we would avoid adding fileOrDir to the files list if it was a directory. Is it correct to go ahead and add it to the files list here now? Will that cause a problem later on in this func when we range over the files list and call LoadYAMLStreamFromFile on each of them?

[jbw976]

ah nevermind, it shouldn't be an issue, because in the case of a directory we end up overwriting the files list with the yamls list that comes back from getYAMLFiles(). sounds good!

[jbw976]

I also took this for a quick test spin with the demo scenario in https://github.com/jbw976/demo-xfn/tree/main/kcl. It looks like it works correctly when you pipe various resources to render which it will then read via stdin 🤩

• XR: cat xr-without-gateway.yaml | ./crank-stdin beta render - composition.yaml functions.yaml -r
• Composition: cat composition.yaml | ./crank-stdin beta render xr-without-gateway.yaml - functions.yaml -r
• Functions: cat functions.yaml | ./crank-stdin beta render xr-without-gateway.yaml composition.yaml - -r

Example output of piping the composition to stdin:

❯ cat composition.yaml | ./crank-stdin beta render xr-without-gateway.yaml - functions.yaml -r
---
apiVersion: demo-kcl.crossplane.io/v1alpha1
kind: XNetwork
metadata:
  name: xnetwork-kcl
status:
  conditions:
  - lastTransitionTime: "2024-01-01T00:00:00Z"
    message: 'Unready resources: vpc-0'
    reason: Creating
    status: "False"
    type: Ready
---
apiVersion: ec2.aws.upbound.io/v1beta1
kind: VPC
metadata:
  annotations:
    crossplane.io/composition-resource-name: vpc-0
  generateName: xnetwork-kcl-
  labels:
    crossplane.io/composite: xnetwork-kcl
    networks.meta.fn.crossplane.io/network-id: xnetwork-kcl
    networks.meta.fn.crossplane.io/vpc-id: vpc-0
  name: vpc-0
  ownerReferences:
  - apiVersion: demo-kcl.crossplane.io/v1alpha1
    blockOwnerDeletion: true
    controller: true
    kind: XNetwork
    name: xnetwork-kcl
    uid: ""
spec:
  forProvider:
    cidrBlock: 192.168.0.0/16
    enableDnsHostnames: true
    enableDnsSupport: true
    region: eu-central-1
  providerConfigRef:
    name: default
---
apiVersion: render.crossplane.io/v1beta1
kind: Result
message: created resource "vpc-0:VPC"
severity: SEVERITY_NORMAL
step: render-with-kcl

[negz]

FWIW, this was mostly a POC. Following up to get it to the finish line isn't a priority for me, unfortunately. I'm happy if someone else wants to take it and run with it. 🙂

[jbw976]

I'm happy if someone else wants to take it and run with it.

Cool @negz, thanks for getting it to here so far! I've got this PR tracked in ##3957, so folks should hopefully find it and take it to the finish line sometime soon.