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nerdctl: Docker-compatible CLI for containerd

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nerdctl is a Docker-compatible CLI for containerd.

✅ Same UI/UX as docker

✅ Supports Docker Compose (nerdctl compose up)

✅ [Optional] Supports rootless mode, without slirp overhead (bypass4netns)

✅ [Optional] Supports lazy-pulling (Stargz, Nydus, OverlayBD)

✅ [Optional] Supports encrypted images (ocicrypt)

✅ [Optional] Supports P2P image distribution (IPFS) (*1)

✅ [Optional] Supports container image signing and verifying (cosign)

nerdctl is a non-core sub-project of containerd.

*1: P2P image distribution (IPFS) is completely optional. Your host is NOT connected to any P2P network, unless you opt in to install and run IPFS daemon.

Examples

Basic usage

To run a container with the default bridge CNI network (10.4.0.0/24):

# nerdctl run -it --rm alpine

To build an image using BuildKit:

# nerdctl build -t foo /some-dockerfile-directory
# nerdctl run -it --rm foo

To build and send output to a local directory using BuildKit:

# nerdctl build -o type=local,dest=. /some-dockerfile-directory

To run containers from docker-compose.yaml:

# nerdctl compose -f ./examples/compose-wordpress/docker-compose.yaml up

See also ./examples/compose-wordpress.

Debugging Kubernetes

To list local Kubernetes containers:

# nerdctl --namespace k8s.io ps -a

To build an image for local Kubernetes without using registry:

# nerdctl --namespace k8s.io build -t foo /some-dockerfile-directory
# kubectl apply -f - <<EOF
apiVersion: v1
kind: Pod
metadata:
  name: foo
spec:
  containers:
    - name: foo
      image: foo
      imagePullPolicy: Never
EOF

To load an image archive (docker save format or OCI format) into local Kubernetes:

# nerdctl --namespace k8s.io load < /path/to/image.tar

To read logs (experimental):

# nerdctl --namespace=k8s.io ps -a
CONTAINER ID    IMAGE                                                      COMMAND                   CREATED          STATUS    PORTS    NAMES
...
e8793b8cca8b    registry.k8s.io/coredns/coredns:v1.9.3                     "/coredns -conf /etc…"    2 minutes ago    Up                 k8s://kube-system/coredns-787d4945fb-mfx6b/coredns
...

# nerdctl --namespace=k8s.io logs -f e8793b8cca8b
[INFO] plugin/reload: Running configuration SHA512 = 591cf328cccc12bc490481273e738df59329c62c0b729d94e8b61db9961c2fa5f046dd37f1cf888b953814040d180f52594972691cd6ff41be96639138a43908
CoreDNS-1.9.3
linux/amd64, go1.18.2, 45b0a11
...

Rootless mode

To launch rootless containerd:

$ containerd-rootless-setuptool.sh install

To run a container with rootless containerd:

$ nerdctl run -d -p 8080:80 --name nginx nginx:alpine

See ./docs/rootless.md.

Install

Binaries are available here: https://github.com/containerd/nerdctl/releases

In addition to containerd, the following components should be installed:

These dependencies are included in nerdctl-full-<VERSION>-<OS>-<ARCH>.tar.gz, but not included in nerdctl-<VERSION>-<OS>-<ARCH>.tar.gz.

Brew

On Linux systems you can install nerdctl via brew:

brew install nerdctl

This is currently not supported for macOS. The section below shows how to install on macOS using brew.

macOS

Lima project provides Linux virtual machines for macOS, with built-in integration for nerdctl.

$ brew install lima
$ limactl start
$ lima nerdctl run -d --name nginx -p 127.0.0.1:8080:80 nginx:alpine

FreeBSD

See ./docs/freebsd.md.

Windows

Docker

To run containerd and nerdctl inside Docker:

docker build -t nerdctl .
docker run -it --rm --privileged nerdctl

Motivation

The goal of nerdctl is to facilitate experimenting the cutting-edge features of containerd that are not present in Docker (see below).

Note that competing with Docker is not the goal of nerdctl. Those cutting-edge features are expected to be eventually available in Docker as well.

Also, nerdctl might be potentially useful for debugging Kubernetes clusters, but it is not the primary goal.

Features present in nerdctl but not present in Docker

Major:

Minor:

Trivial:

Features implemented in nerdctl ahead of Docker

Similar tools

Developer guide

nerdctl is a containerd non-core sub-project, licensed under the Apache 2.0 license. As a containerd non-core sub-project, you will find the:

information in our containerd/project repository.

Compiling nerdctl from source

Run make && sudo make install.

See the header of go.mod for the minimum supported version of Go.

Using go install github.com/containerd/nerdctl/v2/cmd/nerdctl is possible, but unrecommended because it does not fill version strings printed in nerdctl version

Testing

See testing nerdctl.

Contributing to nerdctl

Lots of commands and flags are currently missing. Pull requests are highly welcome.

Please certify your Developer Certificate of Origin (DCO), by signing off your commit with git commit -s and with your real name.

Command reference

Moved to ./docs/command-reference.md

Additional documents

Configuration guide:

Basic features:

Advanced features:

Experimental features:

Implementation details:

Misc: