IaaS Explained: Infrastructure as a Service Guide
Infrastructure as a Service gives customers programmable compute, network, and storage while the provider operates physical facilities and hardware. It is appropriate when a team needs operating-system and network control and can own patching, identity, backups, monitoring, and recovery. If the product only needs an application runtime or database, a managed platform may remove more risk than raw IaaS.
IaaS draws a responsibility boundary
The NIST cloud definition describes IaaS as provisioning processing, storage, networks, and other fundamental resources while the consumer controls operating systems, storage, deployed applications, and selected networking. The provider secures facilities and underlying infrastructure; the customer still owns guest configuration, credentials, exposed ports, workloads, and data.
Provider tools do not erase that split. AWS's shared-responsibility model distinguishes security “of” and “in” the cloud. The exact line changes for each service: a virtual machine, managed database, object store, and serverless function leave different patching, encryption, logging, backup, and availability duties to the customer.
Choose the highest useful abstraction
IaaS fits custom network appliances, legacy software, specialised kernels, lift-and-improve migrations, and platforms whose operators need host-level control. PaaS fits applications that can accept the provider's runtime, scaling, and deployment model. SaaS fits a complete business capability. Containers and Kubernetes are deployment technologies, not service-model synonyms; they can be customer-operated on IaaS or delivered as a managed platform.
Start from recovery and compliance requirements, then select the least infrastructure the team must own. A managed database can be worth more than its price difference if it supplies tested failover and point-in-time recovery. It can also create API and data-format lock-in. Document the exit format, maximum export time, and a restore target before relying on a proprietary service.
Model cost and failure together
A realistic IaaS estimate includes compute commitments, CPU sharing, disks and performance tiers, snapshots, backup retention, load balancers, public addresses, NAT, DNS, cross-zone traffic, egress, logging, monitoring, support, licences, tax, and engineering on-call. Benchmark the actual workload; nominal vCPU and memory are not performance units across providers.
Build a minimal production architecture, then test loss of an instance, zone, credential, network path, and primary database. Verify immutable rebuilds, secret rotation, backup restore, capacity alarms, and account recovery. Terraform or OpenTofu can reproduce declared resources, but state and provider APIs are themselves dependencies; OpenTofu's official introduction and Terraform's state documentation should inform locking, encryption, backup, and recovery of infrastructure state.
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