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This repository enables the use of a container runtime, containerd, to manage Firecracker microVMs. Like traditional containers, Firecracker microVMs offer fast start-up and shut-down and minimal overhead. Unlike traditional containers, however, they can provide an additional layer of isolation via the KVM hypervisor.
Potential use cases of Firecracker-based containers include:
- Sandbox a partially or fully untrusted third party container in its own microVM. This would reduce the likelihood of leaking secrets via the third party container, for example.
- Bin-pack disparate container workloads on the same host, while maintaining a high level of isolation between containers. Because the overhead of Firecracker is low, the achievable container density per host should be comparable to running containers using kernel-based container runtimes, without the isolation compromise of such solutions. Multi-tentant hosts would particularly benefit from this use case.
To maintain compatibility with the container ecosystem, where possible, we use container standards such as the OCI image format.
There are several components in this repository that enable containerd to use Firecracker microVMs to run containers:
- A snapshotter that creates files used as block-devices for pass-through into the microVM. This snapshotter is used for providing the container image to the microVM. The snapshotter runs as an out-of-process gRPC proxy plugin. We currently have two implementations of a snapshotter: a naive copy-ahead implementation and a devmapper-based copy-on-write implementation.
- A control plugin managing the lifecycle of the runtime and implementing our control API to manage the lifecycle of microVMs. The control plugin is compiled in to the containerd binary, which requires us to build a specialized containerd binary for firecracker-containerd.
- A runtime linking containerd (outside the microVM) to the Firecracker virtual machine monitor (VMM). The runtime is implemented as an out-of-process shim runtime communicating over ttrpc.
- An agent running inside the microVM, which invokes
runC via containerd's
containerd-shim-runc-v1to create standard Linux containers inside the microVM. - A root file filesystem image builder that constructs a firecracker microVM root filesystem containing runc and the firecracker-containerd agent.
For more detailed information on the components and how they work, see architecture.md.
Initially, this project allows you to launch one container per microVM. We intend it to be a drop-in component that can run a variety of containerized applications, so the short term roadmap contains work to support container standards such as OCI and CNI. In addition, we intend to support launching multiple containers inside of one microVM. To support the widest variety of workloads, the new runtime component has to work with popular container orchestration frameworks such as Kubernetes and Amazon ECS, so we will work to ensure that the software is conformant or compatible where necessary.
Details of specific roadmap items are tracked in GitHub issues.
For detailed instructions on building and running firecracker-containerd, see the getting started guide and the quickstart guide.
Please use GitHub issues to report problems, discuss roadmap items, or make feature requests.
If you've discovered an issue that may have security implications to users or developers of this software, please do not report it using GitHub issues, but instead follow Firecracker's security reporting guidelines.
Other discussion: For general discussion, please join us in the #containerd
channel on the Firecracker Slack.
This library is licensed under the Apache 2.0 License.