Wondering how AWS Lambda works under the hood? You’re in the right place! To begin with, in this blog, we’ll explore Firecracker, which is the revolutionary technology powering the AWS Lambda Service. More specifically, we’ll delve into what Firecracker is and gain a deeper understanding of its core features. In addition to that, we’ll learn about MicroVMs (Micro Virtual Machines) and uncover how they contribute to the efficiency of serverless computing. Following this, we will explore how to use the Go Firecracker SDK, breaking it down into simple, actionable steps. Step by step, we’ll guide you through launching a Firecracker Virtual Machine using Go. Furthermore, we’ll show you how to set up Firecracker on your machine, ensuring you’re equipped to take full advantage of this powerful technology. With that said, are you ready to dive deep into the technology that powers AWS Lambda? If so, let’s get this fire-crackin’!

Note: Firecracker only works with Linux Machines

What is Firecracker and a Micro Virtual Machine?

Understanding Firecracker

Originally developed by AWS, Firecracker is an innovative technology. Through its thoughtful design, it prioritizes security, speed, and efficiency. As a result, it has enabled the creation and management of lightweight micro virtual machines (MicroVMs). In turn, these MicroVMs are ideal for serverless computing workloads, such as AWS Lambda, primarily because of their minimal overhead and extremely fast startup times. Moreover, this combination of features ensures optimal performance for modern, scalable applications.

MicroVMs Explained

A MicroVM is a lightweight virtual machine that combines the isolation benefits of traditional Virtual Machines with the speed and resource efficiency of containers. In contrast to conventional Virtual Machines, which can be bulky and slow to start, MicroVMs leverage technologies like the KVM or Kernel-Based Virtual Machine. Notably, this approach provides near-native performance while maintaining strong security. Furthermore, it strikes an excellent balance between efficiency and reliability, making it an ideal choice for modern workloads.

Recap for MicroVMs

• Minimal Footprint: Consume fewer resources which allows for higher density of workloads on the same hardware. 
• Fast Boot Times: It can be launched in milliseconds making it perfect for bursty and scalable workloads.
• Strong Isolation: Each MicroVM created is in its isolated environment since it ensures security and stability across different workloads.
• Flexible Configuration: Highly configurable to match the specific requirements of diverse applications.

Setting Up Firecracker, Go, and the Firecracker Go SDK

To provide a hands-on experience, we will now learn how to set up Firecracker and the Go Firecracker SDK. This section ensures you are fully equipped to get started!

Prerequisites

Before we begin, ensure you have the following:

• Linux Machine: Firecracker only works on Linux Environments.
• Root Privileges: Necessary for setting up network interfaces and running firecracker.
• Basic Knowledge of Go: Familiarity with the Go programming language will be beneficial.

Step 1: Install Required Dependencies

Ensure your system meets the necessary prerequisites for Firecracker. For instance, if you’re running Ubuntu:

• Update Your System:
  • sudo apt-get update
  • sudo apt-get upgrade -y
• Install Essential Tools:
  • sudo apt-get install -y git wget build-essential iproute2 qemu-utls

• Load KVM Modules
  • sudo modprobe kvm
  • sudo modprobe kvm_intel For Intel CPUs
  • sudo modprobe kvm_amd For AMD CPUs
• Verify that KVM is Enabled:
  • ls /dev/kvm It should return “dev/kvm” which means KVM is successfully loaded.

If everything is correct, it should return “dev/kvm,” indicating KVM is successfully loaded.

Step 2: Install Firecracker

First, visit the Firecracker Releases Page to find the latest version.

• Next, download the latest Firecracker Binary: 
• • curl -LO https://github.com/firecracker-microvm/firecracker/releases/download/v1.10.1/firecracker-v1.10.1-x86_64.tgz
  • tar -xzvf firecracker-v1.10.1-x86_64.tgz
  • chmod +x release-v1.10.1-x86_64/firecracker-v1.10.1-x86_64
  • sudo mv release-v1.10.1-x86_64/firecracker-v1.10.1-x86_64 /usr/local/bin/firecracker
• Finally, verify the Installation
  • firecracker --version Should return 1.10.1

Step 3: Set Up Kernel and Root Filesystem

For simplicity, this guide uses pre-built images provided by the Firecracker project. However, if desired, you can build your own kernel and root filesystem.

• Download the Kernel Image
  • wget https://s3.amazonaws.com/spec.ccfc.min/img/hello/kernel/hello-vmlinux.bin -O vmlinux.bin
• Create a Root Filesystem using this Bash Script
  • chmod +x filename.sh

Step 4: Set Up Networking

Firecracker requires a TAP network interface to provide networking capabilities to the VM.

• Create a TAP Device 
  • sudo ip tuntap add dev fc-88-tap0 mode tap
sudo ip addr add 169.254.0.21/30 dev fc-88-tap0
sudo ip link set dev fc-88-tap0 up
sudo sysctl -w net.ipv4.conf.fc-88-tap0.proxy_arp=1
sudo sysctl -w net.ipv6.conf.fc-88-tap0.disable_ipv6=1
  • Explanation:
    • TAP Device: fc-88-tap0 is the TAP device that will bridge the host and the VM’s network.
    • IP Addressing : Assign IP addresses in the link-local range to avoid conflicts
    • Proxy ARP: Enables the host to respond to ARP requests on behalf of the VM.
    • Disable IPv6: Simplifies networking by focusing on IPv4.
• Ensure the TAP Device Exists:
  • ip addr show fc-88-tap0 You should see the TAP device with the assigned IP address.

Step 5: Install Go

Visit the official Go Downloads Page for the Latest Go Version.

• Download and Install Go:
  • curl -O https://go.dev/dl/go1.23.4.linux-amd64.tar.gz
  • rm -rf /usr/local/go && tar -C /usr/local -xzf go1.23.4.linux-amd64.tar.gz You may need to run this as root or through sudo
  • export PATH=$PATH:/usr/local/go/bin
  • source ~/.profile or source ~/.bashrc or ~/.zsrhc
  • go version Should output “go version go1.23.4 linux/amd64”

Let’s Try!

First: Initialize a New Go Project

• mkdir firecracker-demo
• cd firecracker-demo
• go mod init firecracker-demo

Second:  Fetch the Firecracker Go SDK

• go get github.com/firecracker-microvm/firecracker-go-sdk

Third: Create a Go File and Paste the Code Below

• touch main.go

Conclusion