The nydus project implements a content-addressable filesystem on top of a RAFS format that improves the current OCI image specification, in terms of container launching speed, image space, and network bandwidth efficiency, as well as data integrity.

The following benchmarking result shows the performance improvement compared with the OCI image for the container cold startup elapsed time on containerd. As the OCI image size increases, the container startup time of using Nydus image remains very short.

Nydus' key features include:

• Container images can be downloaded on demand in chunks for lazy pulling to boost container startup
• Chunk-based content-addressable data de-duplication to minimize storage, transmission and memory footprints
• Merged filesystem tree in order to remove all intermediate layers as an option
• in-kernel EROFS or FUSE filesystem together with overlayfs to provide full POSIX compatibility
• E2E image data integrity check. So security issues like "Supply Chain Attach" can be avoided and detected at runtime
• Compatible with the OCI artifacts spec and distribution spec, so nydus image can be stored in a regular container registry
• Native eStargz image support with remote snapshotter plugin nydus-snapshotter for containerd runtime.
• Various container image storage backends are supported. For example, Registry, NAS, Aliyun/OSS.
• Integrated with CNCF incubating project Dragonfly to distribute container images in P2P fashion and mitigate the pressure on container registries
• Capable to prefetch data block before user IO hits the block thus to reduce read latency
• Record files access pattern during runtime gathering access trace/log, by which user abnormal behaviors are easily caught
• Access trace based prefetch table
• User I/O amplification to reduce the amount of small requests to storage backend.

Currently Nydus includes following tools:

Currently Nydus is supporting the following platforms in container ecosystem:

To try nydus image service:

1. Convert an original OCI image to nydus image and store it somewhere like Docker/Registry, NAS or Aliyun/OSS. This can be directly done by nydusify. Normal users don't have to get involved with nydus-image.
2. Get nydus-snapshotter(containerd-nydus-grpc) installed locally and configured properly. Or install nydus-docker-graphdriver plugin.
3. Operate container in legacy approaches. For example, docker, nerdctl, crictl and ctr.

# build debug binary
make
# build release binary
make release
# build static binary with docker
make docker-static

For more details on how to lazily start a container with nydus-snapshotter and nydus image on Kubernetes nodes or locally use nerdctl rather than CRI, please refer to Nydus Setup

Build Nydus image from directory source: Nydus Image Builder.

Convert OCI image to Nydus image: Nydusify.

Nydus-snapshotter is a non-core sub-project of containerd.

Check out its code and tutorial from Nydus-snapshotter repository. It works as a containerd remote snapshotter to help setup container rootfs with nydus images, which handles nydus image format when necessary. When running without nydus images, it is identical to the containerd's builtin overlayfs snapshotter.

Normally, users do not need to start nydusd by hand. It is started by nydus-snapshotter or nydus-docker-graphdriver when a container rootfs is prepared.

Run Nydusd Daemon to serve Nydus image: Nydusd.

In-kernel EROFS has been fully compatible with RAFS v6 image format since Linux 5.16. In other words, uncompressed RAFS v6 images can be mounted over block devices since then.

Since Linux 5.19, EROFS has added a new file-based caching (fscache) backend. In this way, compressed RAFS v6 images can be mounted directly with fscache subsystem, even such images are partially available. estargz can be converted on the fly and mounted in this way too.

Guide to running Nydus with fscache: Nydus-fscache

Nydus cooperates with Harbor community to develop acceleration-service which provides a general service for Harbor to support image acceleration based on kinds of accelerators like Nydus, eStargz, etc.

Docker graph driver is also accompanied, it helps to start container from nydus image. For more particular instructions, please refer to

• Nydus Graph Driver

Browse the documentation to learn more. Here are some topics you may be interested in:

• A Nydus Tutorial for Beginners
• Nydus Design Doc
• Our talk on Open Infra Summit 2020: Toward Next Generation Container Image
• EROFS, What Are We Doing Now For Containers?
• The Evolution of the Nydus Image Acceleration (Video)
• Introduction to Nydus Image Service on In-kernel EROFS (Video)

• Nydus can also run with macfuse(a.k.a osxfuse).For more details please read nydus with macos.

The containerd remote snapshotter plugin nydus-snapshotter can be used to run nydus images, or to run eStargz images directly by appending --enable-stargz command line option.

In the future, zstd::chunked can work in this way as well.

Nydus aims to form a vendor-neutral opensource image distribution solution to all communities. Questions, bug reports, technical discussion, feature requests and contribution are always welcomed!

We're very pleased to hear your use cases any time. Feel free to reach/join us via Slack and/or Dingtalk

• Slack

  Join our Slack workspace

• Dingtalk

  Join nydus-devel group by clicking URL on your phone.

  You can also search our talking group by number 34971767 and QR code

Nydus bi-weekly technical community meeting is also regularly available, currrently held on Wednesdays at 06:00 UTC (14:00 Beijing, Shanghai) starting from Aug 10, 2022. For more details, please see our HackMD page.