Crossplane 1.18+ provides a unified API for stateful workloads across AWS and GCP. Learn to build provider-agnostic infrastructure today. Full breakdown.
Why multi-cloud state is hard
Stateless services can move between clouds with relatively little friction. Stateful workloads are different. Databases, message brokers, object stores, and disk-backed caches carry identity, schema, credentials, backup policies, and network placement that are tightly coupled to a single provider’s control plane. When those resources live in both AWS and GCP, teams often end up with two Terraform roots, two console workflows, and two sets of operational runbooks—each describing the same intent in different vocabulary.
The cost of that split is not only duplicated YAML. Drift appears when one environment gets a parameter change the other never receives. Failover drills stall because restore paths differ. Ownership blurs: platform teams own “the cloud,” application teams own “the data,” and nobody owns the contract that says both sides stay aligned. A multi-cloud strategy only works if state is expressed once and reconciled everywhere it must exist.
What Crossplane changes with a unified API
Crossplane treats infrastructure as Kubernetes-native APIs. Instead of calling each cloud’s SDK from scripts, you declare desired resources as custom resources and let controllers reconcile them. Crossplane 1.18+ strengthens this model for stateful workloads across AWS and GCP by exposing a more consistent composition surface: you define the shape of the workload once, then map it to provider-specific implementations behind the scenes.
The practical win is a single source of truth. Application and platform owners work against the same API kinds and status fields. Provider packages still talk to AWS or GCP under the hood, but operators reason in terms of claims, compositions, and managed resources rather than two disjoint toolchains. That does not erase cloud differences—latency, IAM models, and storage classes still matter—but it moves those differences into composition logic instead of ad-hoc runbooks.
Building provider-agnostic infrastructure in practice
Start by separating what the app needs from where it runs. A claim might say “I need a durable relational store with automated backups and private network access.” A composition turns that claim into AWS- or GCP-specific managed resources, injecting provider credentials, region, and sizing from environment context. Keep compositions small and reviewable: one composition per workload class beats a giant template that tries to encode every product edge case.
- Model identity and secrets as first-class inputs so rotation and least privilege are not afterthoughts.
- Expose connection details through a stable contract (connection secret, status fields) so apps do not hardcode cloud-specific endpoints.
- Encode backup, retention, and deletion protection in the composition so state lifecycle is declarative, not tribal knowledge.
- Test compositions in a non-production control plane before promoting the same claim shape to production clusters.
Provider-agnostic does not mean provider-blind. Use composition patches and environment configs to choose instance families, disk types, and networking patterns that fit each cloud, while keeping the claim API identical for consumers. That is how teams ship the same product topology on AWS and GCP without rewriting application manifests.
Operational discipline that makes it stick
Reconciliation is continuous, so treat Crossplane the way you treat any control plane: watch resource readiness, surface meaningful status conditions, and gate promotions when managed resources sit in pending or degraded states. Prefer immutable composition versions over in-place edits that surprise running claims. Document which fields are portable and which are cloud-specific so platform consumers know what they can change safely.
Multi-cloud state synchronization succeeds when intent is centralized, differences are explicit, and recovery paths are exercised. Crossplane’s unified API is the mechanism; the discipline is keeping claims thin, compositions honest about provider tradeoffs, and operational signals clear enough that drift is fixed by the controller—not by a late-night console edit in only one cloud.