Upbound supports defining your control plane APIs in KCL, an open source constraint-based record and functional language.
Prerequisites
Install the following:
Example
The example below is a pre-generated function that detects if a composed resource is ready in your infrastructure.
The function file below describes the behavior of your function. This overview describes the core elements below.
import models.v1beta1 as v1beta1
_metadata = lambda name: str -> any {
{ annotations = { "krm.kcl.dev/composition-resource-name" = name }}
}
# This is the observed composite resource, provided as an input to the function
oxr = option("params").oxr
_items = [
v1beta1.Instance {
metadata: _metadata("vm-instance")
spec.forProvider = {
associatePublicIpAddress: True
instanceType: "t3.micro"
availabilityZone: oxr.spec.parameters.locaton
cpuCoreCount: 10
}
}
]
# This function composes an EC2 instance.
items = _items
First, review the import statements.
import models.v1alpha1.nop_crossplane_io_v1alpha1_nop_resource as nopv1alpha1
import models.k8s.apimachinery.pkg.apis.meta.v1 as metav1
The function above can be generated from a corresponding XRD, which maps the resource schema for the resource you want to create.
apiVersion: apiextensions.crossplane.io/v1
kind: CompositeResourceDefinition
metadata:
name: xdatabases.platform.acme.co
spec:
group: platform.acme.co
names:
kind: XDatabase
plural: xdatabases
claimNames:
kind: Database
plural: databases
versions:
- name: v1alpha1
served: true
referenceable: true
schema:
openAPIV3Schema:
type: object
properties:
spec:
type: object
description: |
The specification for how this database should be
deployed.
properties:
parameters:
type: object
description: |
The parameters indicating how this database should
be configured.
properties:
region:
type: string
enum:
- east
- west
description: |
The geographic region in which this database
should be deployed.
size:
type: string
enum:
- small
- medium
- large
description: |
The machine size for this database.
storage:
type: integer
description: |
The storage size for this database in GB.
required:
- region
- size
- storage
required:
- parameters
Compositions reference your function and automatically follow the function logic.
apiVersion: apiextensions.crossplane.io/v1
kind: Composition
metadata:
name: xdatabases.platform.acme.co
spec:
compositeTypeRef:
apiVersion: platform.acme.co/v1alpha1
kind: XDatabase
mode: Pipeline
pipeline:
- step: compose
functionRef:
name: upbound-project-getting-startedxdatabase
- step: automatically-detect-ready-composed-resources
functionRef:
name: crossplane-contrib-function-auto-ready
Control plane project model
The Upbound programming model defines the core concepts you can use when creating your control plane using Upbound. Concepts describes these concepts with examples available in KCL. This section contains guidance specifically for how to use the KCL language to do Crossplane-specific tasks. Read the KCL reference docs for comprehensive instruction.
The KCL experience is made available thanks to the function-kcl function.
