Crossplane

Crossplane is an open-source Kubernetes add-on that extends Kubernetes' functionality by enabling it to manage infrastructure resources. It allows Kubernetes to serve as a control plane for provisioning and managing infrastructure such as databases, cloud services, and other external systems, similar to how it manages containerized applications.

Overview

Key Features

1. Infrastructure as Code: Crossplane allows users to define and manage infrastructure using Kubernetes-native declarative configurations (YAML files), promoting consistency and version control.

2. Composability: Crossplane enables users to create reusable infrastructure components, which can be composed into higher-level abstractions. This makes it easier to manage complex infrastructure setups.

3. Extensibility: It supports a wide range of cloud providers (like AWS, GCP, Azure & Open Telekom Cloud) and on-premises environments. Users can extend Crossplane by writing their own custom resource definitions (CRDs) and controllers.

4. Seamless Integration: By integrating with Kubernetes, Crossplane leverages Kubernetes' existing ecosystem, including its API, RBAC, and ecosystem tools, to provide a unified management interface.

5. Cross-Provider Portability: Crossplane abstracts the underlying infrastructure provider details, allowing for easier migration and multi-cloud strategies. It offers a consistent API regardless of the provider.

How Crossplane Works

• Custom Resource Definitions (CRDs): Crossplane defines CRDs for various infrastructure resources (like databases, storage, networking, etc.). These CRDs extend Kubernetes' API to manage non-container resources.

• Controllers: Crossplane controllers watch for changes to these CRDs and take actions to ensure that the current state matches the desired state, provisioning and managing resources as needed.

• Providers: Crossplane uses providers to interact with specific cloud services or infrastructure resources. Providers encapsulate the logic for managing resources on different platforms.

Use Cases

• Cloud Resource Management: Provision and manage cloud resources such as databases, virtual machines, and networking components using Kubernetes-native tools.
• Hybrid Cloud Deployments: Manage resources across multiple clouds and on-premises environments from a single control plane.
• DevOps Automation: Automate the lifecycle management of infrastructure alongside application deployment processes.

Crossplane essentially brings the principles of Kubernetes orchestration to infrastructure management, enabling a more unified and streamlined approach to handling both application and infrastructure resources within the same ecosystem.

note

You can read more in the official Crossplane Documentation.

Installing Crossplane

note

In order to execute the rest of the blueprint, an existing CCE Cluster is necessary.

We are going to install Crossplane using the official Helm chart:

helm repo add crossplane-stable https://charts.crossplane.io/stable
helm repo update

helm install crossplane \
--namespace crossplane-system \
--create-namespace crossplane-stable/crossplane 

After installing, the Helm chart will create two deployments in the crossplane-system namespace to deploy the Crossplane pods:

kubectl get deployments -n crossplane-system

NAME                      READY   UP-TO-DATE   AVAILABLE   AGE
crossplane                1/1     1            1           8m13s
crossplane-rbac-manager   1/1     1            1           8m13s

Installing Open Telekom Cloud Crossplane Provider

Open Telekom Cloud comes with its own Crossplane provider (provider-opentelekomcloud) that is built using Upjet code generation tools and exposes XRM-conformant managed resources for the Open Telekom Cloud API.

Deploy with kubectl apply -f the following manifests:

1. Installing the Provider

   provider.yaml

    apiVersion: pkg.crossplane.io/v1
    kind: Provider
    metadata:
        name: provider-opentelekomcloud
    spec:
        package: xpkg.upbound.io/opentelekomcloud/provider-opentelekomcloud:v0.1.0

2. Installing the Provider Credentials

   Pass the Open Telekom Cloud credentials as a Kubernetes Secret:

   provider-creds.yaml

   apiVersion: v1
   kind: Secret
   metadata:
   name: provider-opentelekomcloud-creds
   namespace: crossplane-system
   type: Opaque
   stringData:
   credentials: |
       {
       "user_name": "${user_name}",
       "password": "${password}",
       "auth_url": "https://iam.eu-de.otc.t-systems.com/v3",
       "domain_name": "OTC00000000001000XXXXX",
       "tenant_name": "${tenant_name}",
       "swauth": "false",
       "allow_reauth": "true",
       "max_retries": "2",
       "max_backoff_retries": "6",
       "backoff_retry_timeout": "60",
       "insecure": "false"
       }
   note

   Fill in user_name, password, domain_name and tenant_name with your organization's values.

3. Installing the Provider Configuration

   provider-config.yaml

   apiVersion: opentelekomcloud.crossplane.io/v1beta1
   kind: ProviderConfig
   metadata:
   name: default
   spec:
   credentials:
       source: Secret
       secretRef:
       name: provider-opentelekomcloud-creds
       namespace: crossplane-system
       key: credentials

note

After a couple of minutes the Provider will deploy the necessary Pods and CRDs of the Crossplane Provider for Open Telekom Cloud.