容器引擎是Kubernetes最重要的组件之一，负责管理镜像和容器的生命周期。Kubelet通过Container Runtime Interface (CRI) 与容器引擎交互，以管理镜像和容器。

表1 容器引擎对比

Containerd和Docker组件常用命令对比

表2 镜像相关功能

表3 容器相关功能

表4 Pod相关功能

说明：
Containerd创建并启动的容器会被kubelet立即删除，不支持暂停、恢复、重启、重命名、等待容器，Containerd不具备docker构建、导入、导出、比较、推送、查找、打标签镜像的能力，Containerd不支持复制文件，可通过修改containerd的配置文件实现登录镜像仓库。

调用链区别

• Docker（Kubernetes 1.23及以下版本）：
  kubelet --> docker shim （在kubelet 进程中） --> docker --> containerd

• Docker（Kubernetes 1.24及以上版本社区方案）：
  kubelet --> cri-dockerd （kubelet使用cri接口对接cri-dockerd） --> docker --> containerd

• Containerd：
  kubelet --> cri plugin（在containerd进程中） --> containerd

其中Docker虽增加了swarm cluster、docker build、docker API等功能，但也会引入一些bug，并且与Containerd相比，多了一层调用，因此Containerd被认为更加节省资源且更安全。

Contianerd换源

Containerd通过在启动时指定一个配置文件夹，使后续所有镜像仓库相关的配置都可以在里面热加载，无需重启Containerd。

1. 如果/etc/containerd/config.toml配置文件中已包含config_path配置（例如"/etc/containerd/cert.d"），则无需执行此步骤；如果不存在，您可以在配置文件中添加以下config_path并重启Containerd使更改生效。

config_path = "/etc/containerd/certs.d"

2. 在步骤一中指定的config_path路径中创建docker.io/hosts.toml文件。
   在文件中写入如下配置。

server = "https://registry-1.docker.io"[host."$(镜像加速器地址，如https://xxx.mirror.aliyuncs.com)"]capabilities = ["pull", "resolve", "push"]

镜像加速配置：

# docker hub镜像加速
mkdir -p /etc/containerd/certs.d/docker.io
cat > /etc/containerd/certs.d/docker.io/hosts.toml << EOF
server = "https://docker.io"
[host."https://dockerproxy.com"]capabilities = ["pull", "resolve"][host."https://docker.m.daocloud.io"]capabilities = ["pull", "resolve"][host."https://reg-mirror.qiniu.com"]capabilities = ["pull", "resolve"][host."https://registry.docker-cn.com"]capabilities = ["pull", "resolve"][host."http://hub-mirror.c.163.com"]capabilities = ["pull", "resolve"]EOF# registry.k8s.io镜像加速
mkdir -p /etc/containerd/certs.d/registry.k8s.io
tee /etc/containerd/certs.d/registry.k8s.io/hosts.toml << 'EOF'
server = "https://registry.k8s.io"[host."https://k8s.m.daocloud.io"]capabilities = ["pull", "resolve", "push"]
EOF# docker.elastic.co镜像加速
mkdir -p /etc/containerd/certs.d/docker.elastic.co
tee /etc/containerd/certs.d/docker.elastic.co/hosts.toml << 'EOF'
server = "https://docker.elastic.co"[host."https://elastic.m.daocloud.io"]capabilities = ["pull", "resolve", "push"]
EOF# gcr.io镜像加速
mkdir -p /etc/containerd/certs.d/gcr.io
tee /etc/containerd/certs.d/gcr.io/hosts.toml << 'EOF'
server = "https://gcr.io"[host."https://gcr.m.daocloud.io"]capabilities = ["pull", "resolve", "push"]
EOF# ghcr.io镜像加速
mkdir -p /etc/containerd/certs.d/ghcr.io
tee /etc/containerd/certs.d/ghcr.io/hosts.toml << 'EOF'
server = "https://ghcr.io"[host."https://ghcr.m.daocloud.io"]capabilities = ["pull", "resolve", "push"]
EOF# k8s.gcr.io镜像加速
mkdir -p /etc/containerd/certs.d/k8s.gcr.io
tee /etc/containerd/certs.d/k8s.gcr.io/hosts.toml << 'EOF'
server = "https://k8s.gcr.io"[host."https://k8s-gcr.m.daocloud.io"]capabilities = ["pull", "resolve", "push"]
EOF# mcr.m.daocloud.io镜像加速
mkdir -p /etc/containerd/certs.d/mcr.microsoft.com
tee /etc/containerd/certs.d/mcr.microsoft.com/hosts.toml << 'EOF'
server = "https://mcr.microsoft.com"[host."https://mcr.m.daocloud.io"]capabilities = ["pull", "resolve", "push"]
EOF# nvcr.io镜像加速
mkdir -p /etc/containerd/certs.d/nvcr.io
tee /etc/containerd/certs.d/nvcr.io/hosts.toml << 'EOF'
server = "https://nvcr.io"[host."https://nvcr.m.daocloud.io"]capabilities = ["pull", "resolve", "push"]
EOF# quay.io镜像加速
mkdir -p /etc/containerd/certs.d/quay.io
tee /etc/containerd/certs.d/quay.io/hosts.toml << 'EOF'
server = "https://quay.io"[host."https://quay.m.daocloud.io"]capabilities = ["pull", "resolve", "push"]
EOF# registry.jujucharms.com镜像加速
mkdir -p /etc/containerd/certs.d/registry.jujucharms.com
tee /etc/containerd/certs.d/registry.jujucharms.com/hosts.toml << 'EOF'
server = "https://registry.jujucharms.com"[host."https://jujucharms.m.daocloud.io"]capabilities = ["pull", "resolve", "push"]
EOF# rocks.canonical.com镜像加速
mkdir -p /etc/containerd/certs.d/rocks.canonical.com
tee /etc/containerd/certs.d/rocks.canonical.com/hosts.toml << 'EOF'
server = "https://rocks.canonical.com"[host."https://rocks-canonical.m.daocloud.io"]capabilities = ["pull", "resolve", "push"]
EOF

参考：

1. https://support.huaweicloud.com/usermanual-cce/cce_10_0462.html
2. https://help.aliyun.com/zh/acr/user-guide/accelerate-the-pulls-of-docker-official-images?spm=5176.28426678.J_HeJR_wZokYt378dwP-lLl.11.55d25181Z6Gz74&scm=20140722.S_help@@%E6%96%87%E6%A1%A3@@60750.S_BB2@bl+RQW@ag0+BB1@ag0+os0.ID_60750-RL_etccontainerd-LOC_search_UNDhelpdoc_UNDitem-OR_ser-V_3-P0_0
3. https://blog.csdn.net/IOT_AI/article/details/131975562