What you need to know about Lambda MicroVMs

AWS launched Lambda MicroVMs, a new compute primitive that combines VM-level isolation (via Firecracker), fast startup from pre-initialized snapshots, and stateful sessions lasting up to 8 hours. Unlike standard Lambda functions, MicroVMs expose a persistent HTTPS endpoint per user/session, support HTTP/2, gRPC, and WebSockets, and allow shell access and Docker inside the VM. The primary use case is safely running AI-generated or user-supplied code in sandboxed environments. Key caveats include ARM64-only support, availability in only five regions, and Fargate-like pricing. The post also compares Lambda MicroVMs with AgentCore Runtime: AgentCore is a managed agent platform with fleet management and built-in protocols, while Lambda MicroVMs is a low-level primitive giving full VM control — analogous to Fargate vs. EC2.