Latest Firecracker Virtualization Overview

Posted on Dec 11

• Originally published at bacchi.org

Firecracker is an open source virtualization technology created by Amazon Web Services (AWS) which underpins their AWS Lambda Functions as a Service (FaaS) serverless product.

Firecracker was open sourced in 2018 [0], making it possible for anyone to use this extremely fast and reliable system for their own projects and use cases.

I've been researching the ecosystem lately and am impressed at the flexibility architected into the Firecracker code which enables it to be used in many ways. We might have expected them to design it such that it only works in their very tightly controlled environment. But the fact that it's not specialized to just the AWS Lambda use case means that it can be leveraged by anyone from AWS scale to a home lab running a single VM.

Let's explore the capabilities of Firecracker and the various methods of using it.

There are many good quick start documents 1 and blogs describing how to install and start a single Firecracker MicroVM instance. Because of these great resources readily available, I won't describe that here.

When you start a firecracker VM by executing the firecracker program, you are running a single VM instance which can be managed through the firecracker process you launched it with. You can send subsequent commands to perform additional management tasks to the firecracker process using the API via a unix socket. When you are done with the VM you can and should stop it "gracefully".

Multiple firecracker processes can be executed at one time, which translates to running multiple VMs. Presumably this is how AWS runs millions of Lambda functions.

If you use the configuration file to set the VM guest kernel and rootfs, you can still use the socket to send API requests. These configuration methods seem to conflict, but they appear to me to be part of the design of a highly flexible system.

The HTTP API is enhanced by what appears to be an official Go SDK [4] that you can use to manage your Firecracker VM instances. A likely scenario is that AWS uses this Go SDK to provision and control their Lambda functions via this HTTP API provided by the Firecracker process.

Source: Dev.to