Pure public cloud is not the right answer for every workload. Regulatory requirements, data sovereignty concerns, latency constraints, and the cost of migrating legacy systems mean that most enterprises operate—and will continue to operate—in a hybrid environment. The question is not whether to use hybrid cloud, but how to design it well.
What Is Hybrid Cloud?
Hybrid cloud combines on-premises infrastructure (or private cloud) with one or more public cloud services, connected by a network that allows data and applications to move between them. The key principle is orchestration—managing on-premises and cloud resources through a unified control plane.
This is distinct from multi-cloud (using multiple public cloud providers) though most enterprise environments are both hybrid and multi-cloud simultaneously.
Why Hybrid Cloud?
Regulatory and Data Sovereignty
Many industries—financial services, healthcare, legal, defence—must keep certain data within specific geographic boundaries or on infrastructure they physically control. Hybrid cloud allows regulated data to stay on-premises while unregulated workloads benefit from public cloud economics.
Legacy System Integration
Modernising a 15-year-old ERP system is a multi-year programme. Hybrid cloud lets you extend and integrate legacy systems with cloud-native capabilities without requiring a big-bang migration.
Cost Optimisation
- Run predictable, stable workloads on-premises (where the cost per compute hour is lower at scale)
- Burst to public cloud for variable, seasonal, or unpredictable demand
- Avoid over-provisioning on-premises capacity
Disaster Recovery and Resilience
Use the public cloud as a cost-effective DR target for on-premises systems, achieving enterprise-grade resilience without building and maintaining a second physical data centre.
Designing Your Hybrid Cloud Architecture
Step 1: Workload Classification
Classify every workload into one of four categories:
| Category | Characteristics | Recommended Placement |
|---|---|---|
| Cloud-native | Stateless, containerised, modern stack | Public cloud |
| Cloud-friendly | Can migrate with moderate refactoring | Public cloud (lift-and-shift first) |
| Cloud-sensitive | Regulatory constraints, latency needs | On-premises / private cloud |
| Cloud-incompatible | Legacy, deeply coupled, high migration cost | On-premises (modernise over time) |
Step 2: Define the Connectivity Model
Connectivity between on-premises and cloud must be reliable, secure, and low-latency:
- Site-to-Site VPN: Encrypted tunnel over internet. Cost-effective for moderate workloads but variable latency.
- Dedicated private connectivity: Azure ExpressRoute, AWS Direct Connect, Google Cloud Interconnect. Predictable performance and lower latency; higher cost.
- SD-WAN: Software-defined WAN overlay that optimises traffic routing across multiple connectivity paths.
For production workloads, dedicated private connectivity is strongly recommended.
Step 3: Unified Identity and Access Management
Hybrid cloud security starts with identity:
- Extend on-premises Active Directory to the cloud via Azure AD Connect (for Microsoft environments) or equivalent directory synchronisation
- Single Sign-On (SSO) across on-premises and cloud applications
- Conditional Access policies that evaluate device compliance, user location, and risk before granting access
- Privileged Identity Management (PIM) for cloud administrative access
Step 4: Consistent Security Controls
Avoid the trap of strong on-premises security with weak cloud controls (or vice versa):
- Apply the same security baseline (patching, EDR, logging) to cloud VMs as to on-premises servers
- Extend on-premises SIEM (or deploy a cloud-native SIEM) to ingest logs from both environments
- Use Cloud Security Posture Management (CSPM) tools to detect cloud misconfigurations
- Implement DLP policies that follow data regardless of whether it is on-premises or in the cloud
Step 5: Hybrid Management Tooling
Manage both environments through a single control plane:
- Azure Arc: Extend Azure management and policy to on-premises and multi-cloud servers
- AWS Outposts: Run AWS infrastructure on-premises for true hybrid consistency
- VMware Cloud Foundation: Unified platform for on-premises and cloud VMware environments
- HashiCorp Terraform: Infrastructure-as-code across multiple providers
Common Hybrid Cloud Pitfalls
Network Latency Assumptions
Applications designed for low-latency local networks may perform poorly when data must traverse a WAN link to the cloud. Profile application latency requirements before deciding on placement.
Inconsistent Security Posture
Teams often apply rigorous change control and security hardening to on-premises systems but treat cloud environments as ad-hoc. Enforce the same standards everywhere.
Cost Visibility
Cloud costs are dynamic and can surprise organisations accustomed to fixed on-premises CAPEX. Implement FinOps practices: tagging, budgets, anomaly detection, and regular cost reviews.
Complexity Creep
Hybrid cloud is inherently more complex than a single environment. Resist the urge to use every available service; start with a small set of well-understood patterns and expand deliberately.
Measuring Hybrid Cloud Success
Track these metrics quarterly:
- Unit cost per workload (on-premises vs cloud vs hybrid)
- Cloud cost as % of IT budget (target: transparent and budgeted, not surprising)
- Security policy compliance rate across both environments
- Mean Time to Provision new environments (should improve with automation)
- Application availability for workloads spanning both environments
A well-designed hybrid cloud strategy is not a compromise between security and flexibility—it is the architecture that delivers both, applied intelligently based on the characteristics of each workload.