xrender

Important

xrender is now crossplane render, which lives at https://github.com/crossplane/crossplane.

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

# See how to use it
$ xrender --help
Usage: xrender <composite-resource> <composition> <functions>

Render an XR using Composition Functions.

Arguments:
  <composite-resource>    A YAML manifest containing the Composite Resource (XR) to render.
  <composition>           A YAML manifest containing the Composition to use. Must be mode: Pipeline.
  <functions>             A YAML stream of manifests containing the Composition Functions to use.

Flags:
  -h, --help                         Show context-sensitive help.
  -d, --debug                        Emit debug logs in addition to info logs.
      --timeout=3m                   How long to run before timing out.
  -o, --observed-resources=STRING    An optional YAML stream of manifests mocking the observed state of composed resources.

# Try it out using the examples in this repository
$ xrender examples/xr.yaml examples/composition.yaml examples/functions.yaml
---
apiVersion: nopexample.org/v1
kind: XBucket
metadata:
  name: test-xrender
status:
  bucketRegion: us-east-2
---
apiVersion: s3.aws.upbound.io/v1beta1
kind: Bucket
metadata:
  annotations:
    crossplane.io/composition-resource-name: my-bucket
  generateName: test-xrender-
  labels:
    crossplane.io/composite: test-xrender
  ownerReferences:
  - apiVersion: nopexample.org/v1
    blockOwnerDeletion: true
    controller: true
    kind: XBucket
    name: test-xrender
    uid: ""
spec:
  forProvider:
    region: us-east-2

How does it work?

xrender only supports Compositions in mode: Pipeline - i.e. Compositions that are powered by Composition Functions. It works by:

1. Running the pipeline of Composition Functions locally.
2. Running your XR through the pipeline.
3. Printing the results to stdout.

You can also pass the -o flag to pass a series of "observed composed resources" to the pipeline along with your XR. This is useful to see how your Composition would work if some of its composed resources already existed, for example to test out copying composed resource status back to the XR.

By default xrender uses Docker to run Functions locally.

Configuration

xrender uses "runtimes" to run Functions. It's designed to easily be extended with new runtimes. Right now it supports two:

• Docker (default) - run Functions using a Docker daemon.
• Development - connect to a Function running locally (e.g. using go run).

You can configure which runtime to use on a Function-by-Function basis. This is handy for developing Functions. Say your Composition uses a pipeline of three Functions, and you're developing one of them. You can run the two "stable" Functions using the Docker runtime, and use the Development runtime to tell xrender to connect to the Function you're running locally.

You configure what runtime to use by adding annotations to the Function packages in functions.yaml. The following annotations are supported:

• xrender.crossplane.io/runtime: Docker (default) - Use the Docker runtime.
• xrender.crossplane.io/runtime: Development - Use the Development runtime.

The Docker runtime supports the following additional annotations:

• xrender.crossplane.io/runtime-docker-cleanup: Stop (default) - Stop the Docker container after rendering the XR.
• xrender.crossplane.io/runtime-docker-cleanup: Orphan - Leave the Docker container running after rendering the XR.
• xrender.crossplane.io/runtime-docker-image - Override the image used to run the Function. The Function's spec.package is used by default.

For example:

---
apiVersion: pkg.crossplane.io/v1beta1
kind: Function
metadata:
  name: function-dummy
  annotations:
    xrender.crossplane.io/runtime: Docker
    xrender.crossplane.io/runtime-docker-cleanup: Orphan
    xrender.crossplane.io/runtime-docker-image: 690d376c2b2a # Some local image build.
spec:
  package: xpkg.upbound.io/crossplane-contrib/function-dummy:v0.2.1

The Development runtime supports the following additional annotation:

• xrender.crossplane.io/runtime-development-target - The gRPC 'target' address at which the Function is listening. The default is localhost:9443.

Note that the Development runtime requires the Function to be listening in --insecure mode, i.e. without mTLS transport security.

For example:

---
apiVersion: pkg.crossplane.io/v1beta1
kind: Function
metadata:
  name: function-dummy
  annotations:
    xrender.crossplane.io/runtime: Development
    xrender.crossplane.io/runtime-development-target: localhost:9443 # A Function running locally
spec:
  package: xpkg.upbound.io/crossplane-contrib/function-dummy:v0.2.1

Future Improvements

xrender is an early implementation. It doesn't yet support:

• Automatically rendering nested XRs.
• Rendering the XR's connection details.
• Determining whether the XR would be considered ready.
• Providing mocked observed composed resource connection details.