Crossplane — Infrastructure as Kubernetes Resource

[khalilbenaz]

---

lede: Crossplane permet de provisionner AWS/GCP/Azure via Kubernetes manifests. Alternative GitOps à Terraform pour équipes K8s-native.
lede_en: Crossplane provisions AWS/GCP/Azure via Kubernetes manifests. GitOps alternative to Terraform for K8s-native teams.
title_en: Crossplane — Infrastructure as Kubernetes Resource

Crossplane — l'IaC via K8s

Crossplane (CNCF) installe des CRDs dans votre cluster K8s qui exposent les ressources cloud (S3 bucket, RDS, etc.) comme des objets Kubernetes.

apiVersion: rds.aws.upbound.io/v1beta1
kind: Instance
metadata:
  name: my-db
spec:
  forProvider:
    region: us-east-1
    engine: postgres
    engineVersion: "16"
    instanceClass: db.t3.medium
    allocatedStorage: 20
  providerConfigRef:
    name: aws-default

kubectl apply → Crossplane provisionne le RDS sur AWS.

Compositions — l'abstraction

Vous packagez plusieurs ressources comme un XR (Composite Resource) :

apiVersion: platform.example.com/v1alpha1
kind: PostgresInstance
metadata:
  name: my-db
spec:
  size: small
  region: eu-west-1

Sous le capot : crée RDS + IAM role + Secrets + Backup policy automatiquement.

Vos devs utilisent un XR simple. Platform team définit la composition.

Vs Terraform

	Crossplane	Terraform
Source vérité	K8s cluster	State file (S3)
Reconciliation	Continue	One-shot apply
GitOps	Natif via ArgoCD	Nécessite Atlantis
Multi-cloud	Oui	Oui
Communauté	Croissante	Énorme
Talent pool	Petit	Large

Crossplane gagne sur : GitOps natif, reconciliation continue (auto-fix drift), abstraction via compositions.

Terraform gagne sur : maturité, talent disponible, écosystème modules.

Cas d'usage

Platform team : exposer une "internal platform API" aux devs via XRs. Self-service infrastructure.

Multi-cluster : provisionner clusters K8s + leurs ressources cloud depuis un cluster control plane.

GitOps strict : tout dans git, ArgoCD sync infrastructure ET apps.

Setup

helm install crossplane crossplane-stable/crossplane

# Install providers
kubectl apply -f provider-aws.yaml
kubectl apply -f provider-config.yaml

# Now AWS resources as K8s
kubectl apply -f my-bucket.yaml

Effort initial : 1-2 jours pour setup propre.

Verdict

Pour équipes K8s-natives sérieuses : Crossplane mérite évaluation. Self-service infra + GitOps unified.

Pour équipes Terraform productives : pas raison forte de migrer. Coexistence possible (Crossplane pour internal abstractions, Terraform pour cloud raw).

Crossplane — IaC via K8s

Crossplane (CNCF) installs CRDs in your K8s cluster exposing cloud resources (S3 bucket, RDS, etc.) as Kubernetes objects.

apiVersion: rds.aws.upbound.io/v1beta1
kind: Instance
metadata:
  name: my-db
spec:
  forProvider:
    region: us-east-1
    engine: postgres
    engineVersion: "16"
    instanceClass: db.t3.medium
    allocatedStorage: 20
  providerConfigRef:
    name: aws-default

kubectl apply → Crossplane provisions the RDS on AWS.

Compositions — the abstraction

You package multiple resources as a XR (Composite Resource):

apiVersion: platform.example.com/v1alpha1
kind: PostgresInstance
metadata:
  name: my-db
spec:
  size: small
  region: eu-west-1

Underneath: creates RDS + IAM role + Secrets + Backup policy automatically.

Your devs use a simple XR. Platform team defines the composition.

vs Terraform

	Crossplane	Terraform
Truth source	K8s cluster	State file (S3)
Reconciliation	Continuous	One-shot apply
GitOps	Native via ArgoCD	Needs Atlantis
Multi-cloud	Yes	Yes
Community	Growing	Huge
Talent pool	Small	Large

Crossplane wins on: native GitOps, continuous reconciliation (auto-fix drift), abstraction via compositions.

Terraform wins on: maturity, available talent, module ecosystem.

Use cases

Platform team: expose an "internal platform API" to devs via XRs. Self-service infrastructure.

Multi-cluster: provision K8s clusters + their cloud resources from a control plane cluster.

Strict GitOps: everything in git, ArgoCD syncs infrastructure AND apps.

Setup

helm install crossplane crossplane-stable/crossplane

# Install providers
kubectl apply -f provider-aws.yaml
kubectl apply -f provider-config.yaml

# Now AWS resources as K8s
kubectl apply -f my-bucket.yaml

Initial effort: 1-2 days for clean setup.

Verdict

For serious K8s-native teams: Crossplane deserves evaluation. Self-service infra + unified GitOps.

For productive Terraform teams: no strong reason to migrate. Coexistence possible (Crossplane for internal abstractions, Terraform for raw cloud).

[MikeGarciaAGM]

Implemented and opened PR for this issue: #343

Scope:

• add issue content to posts.json as a new post entry
• preserve existing structure/order