Multi-Cloud Architecture: AWS, Azure, and GCP

Building resilient applications across multiple cloud providers requires careful planning and architecture decisions. Here's what we've learned from managing multi-cloud infrastructure at scale.

Why Multi-Cloud?

**Vendor diversification** - Avoid lock-in to a single provider

**Geographic coverage** - Leverage best regions from each provider

**Cost optimization** - Use the most economical option for each workload

**Redundancy** - True disaster recovery across cloud providers

Key Challenges

1. Network Complexity

Connecting VPCs across AWS, Azure VNets, and GCP requires careful routing and security group management.

2. Identity Management

Each provider has different IAM models. We use OIDC federation to centralize authentication.

3. Cost Tracking

Normalizing billing across providers is non-trivial. We built custom dashboards using FinOps tools.

Architecture Patterns

**Hub and Spoke**: Centralized management cluster with workloads distributed across clouds.

**Active-Active**: Full redundancy with traffic distribution across all clouds.

**Best of Breed**: Use each cloud's strongest services (e.g., AWS Lambda, GCP BigQuery, Azure AD).

Conclusion

Multi-cloud adds complexity but provides unmatched resilience when done correctly.