Get Started on Crossplane

Install Crossplane

Crossplane installs into an existing Kubernetes cluster, creating the Crossplane pod.

Installing Crossplane enables the installation of Crossplane Provider, Function, and Configuration resources.

Tip

If you don’t have a Kubernetes cluster create one locally with Kind.

Prerequisites

An actively supported Kubernetes version
Helm version v3.2.0 or later

Install Crossplane

Install Crossplane using the Helm chart.

Get Started With Composition

This guide shows how to create a new kind of custom resource named App. When a user calls the custom resource API to create an App, Crossplane creates a Deployment and a Service.

Crossplane calls this composition. The App is composed of the Deployment and the Service.

Tip

The guide shows how to configure composition using YAML, YAML+CEL, templated YAML, Python, and KCL. You can pick your preferred language.

An App custom resource looks like this:

Get Started With Managed Resources

This guide shows how to install and use a new kind of custom resource called Bucket. When a user calls the custom resource API to create a Bucket, Crossplane creates a bucket in AWS S3.

Crossplane calls this a managed resource. A managed resource is a ready-made custom resource that manages something outside of the control plane.

A Bucket managed resource looks like this:

1apiVersion: s3.aws.m.upbound.io/v1beta1
2kind: Bucket
3metadata:
4 namespace: default
5 name: crossplane-bucket-example
6spec:
7 forProvider:
8 region: us-east-2

Note

Kubernetes calls third party API resources custom resources.

Prerequisites

This guide requires:

Get Started With Operations

This guide shows how to use Crossplane Operations to automate day-two operational tasks. You create an Operation that checks SSL certificate expiry for a website.

Crossplane calls this Operations. Operations run function pipelines to perform tasks that don’t fit the typical resource creation pattern - like certificate monitoring, rolling upgrades, or scheduled maintenance.

An Operation looks like this:

 1apiVersion: ops.crossplane.io/v1alpha1
 2kind: Operation
 3metadata:
 4 name: check-cert-expiry
 5spec:
 6 mode: Pipeline
 7 pipeline:
 8 - step: check-certificate
 9 functionRef:
10 name: crossplane-contrib-function-python
11 input:
12 apiVersion: python.fn.crossplane.io/v1beta1
13 kind: Script
14 script: |
15 import ssl
16 import socket
17 from datetime import datetime
18
19 from crossplane.function import request, response
20
21 def operate(req, rsp):
22 hostname = "google.com"
23 port = 443
24
25 # Get SSL certificate info
26 context = ssl.create_default_context()
27 with socket.create_connection((hostname, port)) as sock:
28 with context.wrap_socket(sock, server_hostname=hostname) as ssock:
29 cert = ssock.getpeercert()
30
31 # Parse expiration date
32 expiry_date = datetime.strptime(cert['notAfter'], '%b %d %H:%M:%S %Y %Z')
33 days_until_expiry = (expiry_date - datetime.now()).days
34
35 # Return results in operation output
36 response.set_output(rsp, {
37 "hostname": hostname,
38 "certificateExpires": cert['notAfter'],
39 "daysUntilExpiry": days_until_expiry,
40 "status": "warning" if days_until_expiry < 30 else "ok"
41 })

The Operation runs once to completion, like a Kubernetes Job.