j4flmao AWS Serverless: Deep Dive into Lambda and Firecracker
AWS Lambda abstracts infrastructure, but under the hood, it relies heavily on Firecracker microVMs. Firecracker uses the KVM (Kernel-based Virtual Machine) to provision and manage secure, lightweight microVMs. A microVM has a minimal device model, stripping away unnecessary hardware emulation to achieve boot times of <125ms and a memory footprint of <5MB per VM.
When a Lambda function is invoked for the first time (a cold start), the Firecracker hypervisor allocates a new microVM. The control plane downloads the function package, initializes the language runtime, and executes the user's initialization code.
%%{init: {"theme": "default", "flowchart": {"useMaxWidth": true}}}%%
flowchart TD
subgraph CPControlPlane ["Control Plane<br><br><br>"]
A[API Gateway] -->|"Invoke()"| B[Worker Node]
end
subgraph VMFirecrackermicroVM ["Firecracker microVM<br><br><br>"]
B --> C[MicroVM Init]
C -->|"LoadRuntime()"| D[Language Runtime]
D -->|"ExecuteHandler()"| E[Function Code]
end