简介
nerdctl 是用于 containerd 并且 兼容 docker cli 习惯的管理工具，主要适用于刚从 docker 转到 containerd 的用户，操作 containerd 的命令行工具 ctr 和 crictl 不怎么好用，所以就有了 nerdctl。
要特别说明的是：nerdctl 操作的是 containerd 而非 docker，所以 nerdctl images 和 docker images 看到的内容不同，它只是用法保持了 docker cli 的习惯，实质上操作的是 containerd。
nerdctl 的使用和 docker 一致，与 docker 具有相同的体验，主要特征如下：
✅ 与 docker 的 UI/UX 相同
✅ 支持 docker-compose ( 例如：nerdctl compose up)
✅ [可选] 支持 rootless 模式，无 slirp 开销（bypass4netns）
✅ [可选] 支持延迟拉取（Stargz、Nydus、OverlayBD）
✅ [可选] 支持加密镜像（ocicrypt）
✅ [可选] 支持 P2P 镜像分发 (IPFS) (*1)
✅ [可选] 支持容器镜像签名和验证（cosign）
✅ [可选] 支持 containerd 的命名空间查看，nerdctl不仅可以管理Docker容器，也可以直接管理本地的的Kubernetes pod。
✅ [可选] 支持将Docker Image Manifest镜像转换为OCI镜像、estargz镜像。
nerdctl 是 containerd 的非核心子项目，更多资料详见官网。
安装
nerdctl 的安装分为 Minimal 精简安装和包含一些插件的 Full 完整安装。精简版只包含 nerdctl，完整版包含 nerdctl 和 CNI 插件等依赖（当然你也可以在精简安装的基础上再自己添加 CNI 等插件）。
- Minimal (nerdctl-1.0.0-linux-amd64.tar.gz): nerdctl only
- Full (nerdctl-full-1.0.0-linux-amd64.tar.gz): Includes dependencies such as containerd, runc, and CNI
下载安装
官方下载地址： https://github.com/containerd/nerdctl/releases，在 Asset 中选择下载精简或者完全安装包（本例精简安装）。
[root@test tmp]# wget https://github.com/containerd/nerdctl/releases/download/v1.0.0/nerdctl-1.0.0-linux-amd64.tar.gz
[root@test tmp]# tar -xzvf nerdctl-*-linux-amd64.tar.gz -C /usr/local/bin/
查看版本号验证安装
[root@test tmp] nerdctl --version
nerdctl version 1.0.0
命令
输入 nerdctl -h 查看帮助，列出所有命令说明，如下：
[root@test tmp]# nerdctl -h
nerdctl is a command line interface for containerd
Config file ($NERDCTL_TOML): /etc/nerdctl/nerdctl.toml
Usage: nerdctl [flags]
Management commands:
apparmor Manage AppArmor profiles
builder Manage builds
container Manage containers
image Manage images
ipfs Distributing images on IPFS
namespace Manage containerd namespaces
network Manage networks
system Manage containerd
volume Manage volumes
Commands:
build Build an image from a Dockerfile. Needs buildkitd to be running.
commit Create a new image from a container's changes
completion Generate the autocompletion script for the specified shell
compose Compose
cp Copy files/folders between a running container and the local filesystem.
create Create a new container. Optionally specify "ipfs://" or "ipns://" scheme to pull image from IPFS.
events Get real time events from the server
exec Run a command in a running container
help Help about any command
history Show the history of an image
images List images
info Display system-wide information
inspect Return low-level information on objects.
internal DO NOT EXECUTE MANUALLY
kill Kill one or more running containers
load Load an image from a tar archive or STDIN
login Log in to a container registry
logout Log out from a container registry
logs Fetch the logs of a container. Currently, only containers created with `nerdctl run -d` are supported.
pause Pause all processes within one or more containers
port List port mappings or a specific mapping for the container
ps List containers
pull Pull an image from a registry. Optionally specify "ipfs://" or "ipns://" scheme to pull image from IPFS.
push Push an image or a repository to a registry. Optionally specify "ipfs://" or "ipns://" scheme to push image to IPFS.
rename rename a container
restart Restart one or more running containers
rm Remove one or more containers
rmi Remove one or more images
run Run a command in a new container. Optionally specify "ipfs://" or "ipns://" scheme to pull image from IPFS.
save Save one or more images to a tar archive (streamed to STDOUT by default)
start Start one or more running containers
stats Display a live stream of container(s) resource usage statistics.
stop Stop one or more running containers
tag Create a tag TARGET_IMAGE that refers to SOURCE_IMAGE
top Display the running processes of a container
unpause Unpause all processes within one or more containers
update Update one or more running containers
version Show the nerdctl version information
wait Block until one or more containers stop, then print their exit codes.
Flags:
-H, --H string Alias of --address (default "/run/containerd/containerd.sock")
-a, --a string Alias of --address (default "/run/containerd/containerd.sock")
--address string containerd address, optionally with "unix://" prefix [$CONTAINERD_ADDRESS] (default "/run/containerd/containerd.sock")
--cgroup-manager string Cgroup manager to use ("cgroupfs"|"systemd") (default "cgroupfs")
--cni-netconfpath string cni config directory [$NETCONFPATH] (default "/etc/cni/net.d")
--cni-path string cni plugins binary directory [$CNI_PATH] (default "/opt/cni/bin")
--data-root string Root directory of persistent nerdctl state (managed by nerdctl, not by containerd) (default "/var/lib/nerdctl")
--debug debug mode
--debug-full debug mode (with full output)
--experimental Control experimental: https://github.com/containerd/nerdctl/blob/master/docs/experimental.md [$NERDCTL_EXPERIMENTAL] (default true)
-h, --help help for nerdctl
--host string Alias of --address (default "/run/containerd/containerd.sock")
--hosts-dir strings A directory that contains <HOST:PORT>/hosts.toml (containerd style) or <HOST:PORT>/{ca.cert, cert.pem, key.pem} (docker style) (default [/etc/containerd/certs.d,/etc/docker/certs.d])
--insecure-registry skips verifying HTTPS certs, and allows falling back to plain HTTP
-n, --n string Alias of --namespace (default "default")
--namespace string containerd namespace, such as "moby" for Docker, "k8s.io" for Kubernetes [$CONTAINERD_NAMESPACE] (default "default")
--snapshotter string containerd snapshotter [$CONTAINERD_SNAPSHOTTER] (default "overlayfs")
--storage-driver string Alias of --snapshotter (default "overlayfs")
-v, --version version for nerdctl
Run 'nerdctl COMMAND --help' for more information on a command.
可以通过配置文件
/etc/nerdctl/nerdctl.toml对 nerdctl 进行更多配置。
手工添加插件（按需可选）
以添加 CNI 插件为例，先到 CNI 插件的官方地址下载插件文件。
CNI 需放在指定目录，默认目录为 /opt/cni/bin （这个默认目录在 nerdctl --help 帮助中 --cni-path 后面有说明），nerdctl 会默认查找该目录。
[root@test tmp]# wget https://github.com/containernetworking/plugins/releases/download/v1.1.1/cni-plugins-linux-amd64-v1.1.1.tgz
[root@test tmp]# mkdir -p /opt/cni/bin
[root@test tmp]# tar -xzvf cni-plugins-linux-amd64-v1.1.1.tgz -C /opt/cni/bin
[root@test tmp]# ll /opt/cni/bin/
total 63728
-rwxr-xr-x 1 root root 3780654 Mar 10 2022 bandwidth
-rwxr-xr-x 1 root root 4221977 Mar 10 2022 bridge
-rwxr-xr-x 1 root root 9742834 Mar 10 2022 dhcp
-rwxr-xr-x 1 root root 4345726 Mar 10 2022 firewall
-rwxr-xr-x 1 root root 3811793 Mar 10 2022 host-device
-rwxr-xr-x 1 root root 3241605 Mar 10 2022 host-local
-rwxr-xr-x 1 root root 3922560 Mar 10 2022 ipvlan
-rwxr-xr-x 1 root root 3295519 Mar 10 2022 loopback
-rwxr-xr-x 1 root root 3959868 Mar 10 2022 macvlan
-rwxr-xr-x 1 root root 3679140 Mar 10 2022 portmap
-rwxr-xr-x 1 root root 4092460 Mar 10 2022 ptp
-rwxr-xr-x 1 root root 3484284 Mar 10 2022 sbr
-rwxr-xr-x 1 root root 2818627 Mar 10 2022 static
-rwxr-xr-x 1 root root 3379564 Mar 10 2022 tuning
-rwxr-xr-x 1 root root 3920827 Mar 10 2022 vlan
-rwxr-xr-x 1 root root 3523475 Mar 10 2022 vrf
测试一下
启动一个 nginx 容器，名称为 nginx-test，将宿主机端口 10800 和容器的 80 端口映射
# 启动容器
[root@test tmp]# nerdctl run -d --name nginx-test -p 10800:80 nginx:1.22.1
docker.io/library/nginx:1.22.1: resolved |++++++++++++++++++++++++++++++++++++++|
index-sha256:809f0924101d9c07322d69ab0705e1a0d85b1d0f287e320ae19b0826979c56e9: done |++++++++++++++++++++++++++++++++++++++|
manifest-sha256:fa7e5dee56197a5cbb5b346b3c2c41d91ffa57eb1efcabb5ff09483c87270ccb: done |++++++++++++++++++++++++++++++++++++++|
config-sha256:404359394820dad4c8f210f935939f5890a02ccf82302e1a1068bd0723149736: done |++++++++++++++++++++++++++++++++++++++|
layer-sha256:50b97857b95c8b58fbaa89e528105534fc73606f71e0c4866566b2d6dda2f907: done |++++++++++++++++++++++++++++++++++++++|
layer-sha256:f3c8f37c59f021e336eb6064cb5ef086a44630c8a1cd0728d9b56d584a89fbaf: done |++++++++++++++++++++++++++++++++++++++|
layer-sha256:a603fa5e3b4127f210503aaa6189abf6286ee5a73deeaab460f8f33ebc6b64e2: done |++++++++++++++++++++++++++++++++++++++|
layer-sha256:0edfe97a837abe97ce52b42da5fad5df39a3daccc47b5e4d3bc294375b481a0a: done |++++++++++++++++++++++++++++++++++++++|
layer-sha256:0bf5e07cb0afcd466f3b9f207c8cbaf77a1d483779f37d0189115282e4374dc1: done |++++++++++++++++++++++++++++++++++++++|
layer-sha256:f95a257c65b62fcb59f62f64ab3212e47226f460e9cbfa8c9187f2ab1923ca8c: done |++++++++++++++++++++++++++++++++++++++|
elapsed: 20.9s total: 30.0 M (1.4 MiB/s)
d550e2afd0c1ac924a3047a559c38697167b6b2317a19b3336e43285c6e558dc
# 查看运行中的容器
[root@test tmp]# nerdctl ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
d550e2afd0c1 docker.io/library/nginx:1.22.1 "/docker-entrypoint.…" 32 seconds ago Up 0.0.0.0:10080->80/tcp nginx-test
# 根据容器名称删除容器
[root@test tmp]# nerdctl rm -f nginx-test
nginx-test
通过浏览器可以正常访问：
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