Firecracker CTL

Overview

Rust Axum REST API for managing Firecracker microVMs. Provides VM lifecycle management (create, poll, destroy) with per-VM timeout enforcement and in-memory state tracking via DashMap.

API Endpoints

Method	Path	Description
POST	/vm/create	Create and start a microVM
GET	/vm/{vm_id}	Get VM status
GET	/vm/{vm_id}/result	Get stdout/stderr/exit_code after completion
DELETE	/vm/{vm_id}	Force-terminate a running VM
GET	/vm	List all VMs
GET	/health	Service health check

Code Execution Flow

1. User code arrives via env.CODE in the create request
2. Code is written to a raw block file (512-byte padded)
3. Block file attached as second Firecracker drive (/dev/vdb)
4. Entrypoint passed via boot_args (fc_entrypoint=/usr/bin/python3)
5. VM init script reads code from /dev/vdb, writes to /tmp/code, execs entrypoint

Rootfs Images

Pre-built ext4 root filesystems built in-cluster via ArgoCD PostSync hook:

Image	Size	Contents
alpine-minimal	32 MB	Alpine + busybox
alpine-python	128 MB	Alpine + Python 3.12
alpine-node	128 MB	Alpine + Node.js

Kubernetes Resources

All manifests in apps/kube/firecracker/manifests/:

• Deployment — firecracker-ctl with /dev/kvm device plugin, kvm=true node selector
• Service — ClusterIP on port 9001
• PVC — 2Gi Longhorn volume for rootfs + vmlinux kernel
• NetworkPolicy — Ingress from edge-runtime + dashboard proxy only
• KEDA ScaledObject — minReplicas=1, cron scales to 2 during peak hours
• Rootfs Init Job — ArgoCD PostSync hook, builds ext4 images in-cluster