容器管理工具 Containerd

轻量级或工业级容器管理工具 Containerd

一、Containerd介绍

1.0 前言

• 早在2016年3月，Docker 1.11的Docker Engine里就包含了containerd，而现在则是把containerd从Docker Engine里彻底剥离出来，作为一个独立的开源项目独立发展，目标是提供一个更加开放、稳定的容器运行基础设施。和原先包含在Docker Engine里containerd相比，独立的containerd将具有更多的功能，可以涵盖整个容器运行时管理的所有需求。

• containerd并不是直接面向最终用户的，而是主要用于集成到更上层的系统里，比如Swarm, Kubernetes, Mesos等容器编排系统。

• containerd以Daemon的形式运行在系统上，通过暴露底层的gRPC API，上层系统可以通过这些API管理机器上的容器。

• 每个containerd只负责一台机器，Pull镜像，对容器的操作（启动、停止等），网络，存储都是由containerd完成。具体运行容器由runC负责，实际上只要是符合OCI规范的容器都可以支持。

• 对于容器编排服务来说，运行时只需要使用containerd+runC，更加轻量，容易管理。

• 独立之后containerd的特性演进可以和Docker Engine分开，专注容器运行时管理，可以更稳定。

1.1 Containerd前世今生

2013年docker公司在推出docker产品后,由于其对全球技术产生了一定的影响力，Google公司明显感觉到自己公司内部所使用的Brog系统江湖地位受到的威胁，希望Docker公司能够与自己联合打造一款开源的容器运行时作为Docker核心依赖，但Docker公司拒绝了；接着Google公司联合RedHat、IBM等公司说服Docker公司把其容器核心技术libcontainer捐给中立社区(OCI,Open Container Intiative)，并更名为runC。
为了进一步遏制Docker在未来技术市场影响力，避免在容器市场上Docker一家独大，Google公司带领导RedHat、IBM等成立了CNCF(Cloud Native Computing Fundation)基金会，即云原生计算基金会。CNCF的目标很明确，既然在容器应用领域无法与Docker相抗衡，那就做Google更有经验的技术市场------大规模容器编排应用场景，Google公司把自己内部使用的Brog系统开源------Kubernetes，也就是我们今天所说的云原生技术生态。

2016年Docker公司推出了Docker Swarm，意在一统Docker生态，让Docker既可以实现容器应用管理，也可以实现大规模容器编排，经过近1年左右时间的市场验证后，发现在容器编排方面无法独立抗衡kubernetes,所以Docker公司于2017年正式宣布原生支持Kubernetes,至此，Docker在大规模容器编排应用市场败下阵来，但是Docker依然不甘心失败，把Docker核心依赖Containerd捐给了CNCF，依此说明Docker依旧是一个PaaS平台。

2020年CNCF基金会宣布Kubernetes 1.20版本将不再仅支持Docker容器管理工具，此事的起因主要也与Docker捐给CNCF基金会的Containerd有关，早期为了实现Kubernetes能够使用Docker实现容器管理，专门在Kubernetes组件中集成一个shim（垫片）技术，用来将Kubernetes容器运行时接口（CRI，Container Runntime Interface）调用翻译成Docker的API,这样就可以很好地使用Docker了，但是随着Kubernetes在全球技术市场的广泛应用，有更多的容器管理工具的出现，它们都想能够借助于Kubernetes被用户所使用，所以就提出标准化容器运行时接口，只要适配了这个接口就可以集成到Kubernetes生态当中，所以Kubernetes取消了对shim的维护，并且由于Containerd技术的成功，可以实现无缝对接Kubernetes，所以接下来Kubernetes容器运行时的主角是Containerd。

1.2 Containerd架构

1.2.1 架构图

Containerd设计的目的是为了嵌入到Kubernetes中使用，它是一个工业级的容器运行时，不提供给开发人员和终端用户直接使用，这样就避免了与Docker产生竞争，但事实上，Containerd已经实现大多数容器管理功能，例如：容器生命周期管理、容器镜像传输和管理、容器存储与网络管理等。

• Containerd 采用标准的 C/S 架构

  • 服务端通过 GRPC 协议提供稳定的 API
  • 客户端通过调用服务端的 API 进行高级的操作

• 为了实现解耦，Containerd 将不同的职责划分给不同的组件，每个组件就相当于一个子系统（subsystem）。连接不同子系统的组件被称为模块。

• Containerd 两大子系统为：

  • Bundle : 在 Containerd 中，Bundle 包含了配置、元数据和根文件系统数据，你可以理解为容器的文件系统。而 Bundle 子系统允许用户从镜像中提取和打包 Bundles。
  • Runtime : Runtime 子系统用来执行 Bundles，比如创建容器。

  其中，每一个子系统的行为都由一个或多个模块协作完成（架构图中的 Core 部分）。每一种类型的模块都以插件的形式集成到 Containerd 中，而且插件之间是相互依赖的。

  例如，上图中的每一个长虚线的方框都表示一种类型的插件，包括 Service Plugin、Metadata Plugin、GC Plugin、Runtime Plugin 等，其中 Service Plugin 又会依赖 Metadata Plugin、GC Plugin 和 Runtime Plugin。每一个小方框都表示一个细分的插件，例如 Metadata Plugin 依赖 Containers Plugin、Content Plugin 等。

1.2.2 常用插件

• Content Plugin : 提供对镜像中可寻址内容的访问，所有不可变的内容都被存储在这里。
• Snapshot Plugin : 用来管理容器镜像的文件系统快照。镜像中的每一个 layer 都会被解压成文件系统快照，类似于 Docker 中的 graphdriver。
• Metrics : 暴露各个组件的监控指标。

1.2.3 架构缩略图

Containerd 被分为三个大块：Storage、Metadata 和 Runtime

1.2.4 与其它容器运行时工具性能对比

这是使用 bucketbench 对 Docker、crio 和 Containerd 的性能测试结果，包括启动、停止和删除容器，以比较它们所耗的时间：

结论： Containerd 在各个方面都表现良好，总体性能优于 Docker 和 crio 。

二、Containerd安装

课程操作系统环境为centos7u6

2.1 YUM方式安装

2.1.1 获取YUM源

获取阿里云YUM源
# wget -O /etc/yum.repos.d/docker-ce.repo https://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo

查看YUM源中Containerd软件
# yum list | grep containerd
containerd.io.x86_64                        1.4.12-3.1.el7             docker-ce-stable

2.1.2 使用yum命令安装

安装Containerd.io软件，即可安装Containerd
# yum -y install containerd.io

2.1.3 验证安装及启动服务

使用rpm -qa命令查看是否安装
# rpm -qa | grep containerd
containerd.io-1.4.12-3.1.el7.x86_64

设置containerd服务启动及开机自启动
# systemctl enable containerd
# systemctl start containerd

查看containerd服务启动状态
# systemctl status containerd
● containerd.service - containerd container runtime
   Loaded: loaded (/usr/lib/systemd/system/containerd.service; enabled; vendor preset: disabled)
   Active: active (running) since 五 2022-02-18 11:38:30 CST; 9s ago 此行第二列及第三列表示其正在运行状态
     Docs: https://containerd.io
  Process: 59437 ExecStartPre=/sbin/modprobe overlay (code=exited, status=0/SUCCESS)
 Main PID: 59439 (containerd)
    Tasks: 7
   Memory: 19.5M
   CGroup: /system.slice/containerd.service
           └─59439 /usr/bin/containerd
           ......

2.1.4 验证可用性

安装Containerd时ctr命令亦可使用，ctr命令主要用于管理容器及容器镜像等。
使用ctr命令查看Containerd客户端及服务端相关信息。
# ctr version
Client:
  Version:  1.4.12
  Revision: 7b11cfaabd73bb80907dd23182b9347b4245eb5d
  Go version: go1.16.10

Server:
  Version:  1.4.12
  Revision: 7b11cfaabd73bb80907dd23182b9347b4245eb5d
  UUID: 3c4b142d-d91d-44a5-aae2-9673785d4b2c

2.2 二进制方式安装

Containerd有两种安装包：

• 第一种是containerd-xxx,这种包用于单机测试没问题，不包含runC，需要提前安装。
• 第二种是cri-containerd-cni-xxxx，包含runc和k8s里的所需要的相关文件。k8s集群里需要用到此包。虽然包含runC，但是依赖系统中的seccomp（安全计算模式，是一种限制容器调用系统资源的模式。）

2.2.1 获取安装包

下载Containerd安装包
# wget https://github.com/containerd/containerd/releases/download/v1.6.0/cri-containerd-cni-1.6.0-linux-amd64.tar.gz

2.2.2 安装并测试可用性

2.2.2.1 安装containerd

查看已获取的安装包
# ls
cri-containerd-cni-1.6.0-linux-amd64.tar.gz

解压已下载的软件包
# tar xf cri-containerd-cni-1.6.0-linux-amd64.tar.gz

查看解压后目录
# ls
etc opt  usr 

查看etc目录，主要为containerd服务管理配置文件及cni虚拟网卡配置文件
# ls etc
cni  crictl.yaml  systemd
# ls etc/systemd/
system
# ls etc/systemd/system/
containerd.service


查看opt目录，主要为gce环境中使用containerd配置文件及cni插件
# ls opt
cni  containerd
# ls opt/containerd/
cluster
# ls opt/containerd/cluster/
gce  version
# ls opt/containerd/cluster/gce
cloud-init  cni.template  configure.sh  env

查看usr目录，主要为containerd运行时文件，包含runc
# ls usr
local
# ls usr/local/
bin  sbin
# ls usr/local/bin
containerd  containerd-shim  containerd-shim-runc-v1  containerd-shim-runc-v2  containerd-stress  crictl  critest  ctd-decoder  ctr
# ls usr/local/sbin
runc

2.2.2.2 查看containerd安装位置

查看containerd.service文件，了解containerd文件安装位置
# cat etc/systemd/system/containerd.service



# Copyright The containerd Authors.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

[Unit]
Description=containerd container runtime
Documentation=https://containerd.io
After=network.target local-fs.target

[Service]
ExecStartPre=-/sbin/modprobe overlay
ExecStart=/usr/local/bin/containerd 查看此位置,把containerd二进制文件放置于此处即可完成安装。

Type=notify
Delegate=yes
KillMode=process
Restart=always
RestartSec=5
# Having non-zero Limit*s causes performance problems due to accounting overhead
# in the kernel. We recommend using cgroups to do container-local accounting.
LimitNPROC=infinity
LimitCORE=infinity
LimitNOFILE=infinity
# Comment TasksMax if your systemd version does not supports it.
# Only systemd 226 and above support this version.
TasksMax=infinity
OOMScoreAdjust=-999

[Install]
WantedBy=multi-user.target

2.2.2.3 复制containerd运行时文件至系统

查看宿主机/usr/local/bin目录，里面没有任何内容。
# ls /usr/local/bin/

查看解压后usr/local/bin目录，里面包含containerd运行时文件
# ls usr/
local
# ls usr/local/
bin  sbin
# ls usr/local/bin/
containerd  containerd-shim  containerd-shim-runc-v1  containerd-shim-runc-v2  containerd-stress  crictl  critest  ctd-decoder  ctr

复制containerd文件至/usr/local/bin目录中，本次可仅复制containerd一个文件也可复制全部文件。
# cp usr/local/bin/containerd /usr/local/bin/
# ls /usr/local/bin/
containerd

2.2.2.4 添加containerd.service文件至系统

查看解压后的etc/system目录
# ls etc
cni  crictl.yaml  systemd

# ls etc/systemd/
system

# ls etc/systemd/system/
containerd.service

复制containerd服务管理配置文件至/usr/lib/systemd/system/目录中
# cp etc/systemd/system/containerd.service /usr/lib/systemd/system/containerd.service

查看复制后结果
# ls /usr/lib/systemd/system/containerd.service
/usr/lib/systemd/system/containerd.service

2.2.2.5 查看containerd使用帮助

# containerd --help
NAME:
   containerd -
                    __        _                     __
  _________  ____  / /_____ _(_)___  ___  _________/ /
 / ___/ __ \/ __ \/ __/ __ `/ / __ \/ _ \/ ___/ __  /
/ /__/ /_/ / / / / /_/ /_/ / / / / /  __/ /  / /_/ /
\___/\____/_/ /_/\__/\__,_/_/_/ /_/\___/_/   \__,_/

high performance container runtime


USAGE:
   containerd [global options] command [command options] [arguments...]

VERSION:
   v1.6.0

DESCRIPTION:

containerd is a high performance container runtime whose daemon can be started
by using this command. If none of the *config*, *publish*, or *help* commands
are specified, the default action of the **containerd** command is to start the
containerd daemon in the foreground.


A default configuration is used if no TOML configuration is specified or located
at the default file location. The *containerd config* command can be used to
generate the default configuration for containerd. The output of that command
can be used and modified as necessary as a custom configuration.

COMMANDS:
   config    information on the containerd config
   publish   binary to publish events to containerd
   oci-hook  provides a base for OCI runtime hooks to allow arguments to be injected.
   help, h   Shows a list of commands or help for one command

GLOBAL OPTIONS:
   --config value, -c value     path to the configuration file (default: "/etc/containerd/config.toml")
   --log-level value, -l value  set the logging level [trace, debug, info, warn, error, fatal, panic]
   --address value, -a value    address for containerd's GRPC server
   --root value                 containerd root directory
   --state value                containerd state directory
   --help, -h                   show help
   --version, -v                print the version

2.2.2.6 生成containerd模块配置文件

2.2.2.6.1 生成默认模块配置文件

Containerd 的默认配置文件为 /etc/containerd/config.toml，可以使用containerd config default > /etc/containerd/config.toml命令创建一份模块配置文件

创建配置文件目录
# mkdir /etc/containerd

生成配置文件
# containerd config default > /etc/containerd/config.toml

查看配置文件
# cat /etc/containerd/config.toml
disabled_plugins = []
imports = []
oom_score = 0
plugin_dir = ""
required_plugins = []
root = "/var/lib/containerd"
state = "/run/containerd"
temp = ""
version = 2

[cgroup]
  path = ""

[debug]
  address = ""
  format = ""
  gid = 0
  level = ""
  uid = 0

[grpc]
  address = "/run/containerd/containerd.sock"
  gid = 0
  max_recv_message_size = 16777216
  max_send_message_size = 16777216
  tcp_address = ""
  tcp_tls_ca = ""
  tcp_tls_cert = ""
  tcp_tls_key = ""
  uid = 0

[metrics]
  address = ""
  grpc_histogram = false

[plugins]

  [plugins."io.containerd.gc.v1.scheduler"]
    deletion_threshold = 0
    mutation_threshold = 100
    pause_threshold = 0.02
    schedule_delay = "0s"
    startup_delay = "100ms"

  [plugins."io.containerd.grpc.v1.cri"]
    device_ownership_from_security_context = false
    disable_apparmor = false
    disable_cgroup = false
    disable_hugetlb_controller = true
    disable_proc_mount = false
    disable_tcp_service = true
    enable_selinux = false
    enable_tls_streaming = false
    enable_unprivileged_icmp = false
    enable_unprivileged_ports = false
    ignore_image_defined_volumes = false
    max_concurrent_downloads = 3
    max_container_log_line_size = 16384
    netns_mounts_under_state_dir = false
    restrict_oom_score_adj = false
    sandbox_image = "k8s.gcr.io/pause:3.6"  由于网络原因，此处被替换
    selinux_category_range = 1024
    stats_collect_period = 10
    stream_idle_timeout = "4h0m0s"
    stream_server_address = "127.0.0.1"
    stream_server_port = "0"
    systemd_cgroup = false
    tolerate_missing_hugetlb_controller = true
    unset_seccomp_profile = ""

    [plugins."io.containerd.grpc.v1.cri".cni]
      bin_dir = "/opt/cni/bin"
      conf_dir = "/etc/cni/net.d"
      conf_template = ""
      ip_pref = ""
      max_conf_num = 1

    [plugins."io.containerd.grpc.v1.cri".containerd]
      default_runtime_name = "runc"
      disable_snapshot_annotations = true
      discard_unpacked_layers = false
      ignore_rdt_not_enabled_errors = false
      no_pivot = false
      snapshotter = "overlayfs"

      [plugins."io.containerd.grpc.v1.cri".containerd.default_runtime]
        base_runtime_spec = ""
        cni_conf_dir = ""
        cni_max_conf_num = 0
        container_annotations = []
        pod_annotations = []
        privileged_without_host_devices = false
        runtime_engine = ""
        runtime_path = ""
        runtime_root = ""
        runtime_type = ""

        [plugins."io.containerd.grpc.v1.cri".containerd.default_runtime.options]

      [plugins."io.containerd.grpc.v1.cri".containerd.runtimes]

        [plugins."io.containerd.grpc.v1.cri".containerd.runtimes.runc]
          base_runtime_spec = ""
          cni_conf_dir = ""
          cni_max_conf_num = 0
          container_annotations = []
          pod_annotations = []
          privileged_without_host_devices = false
          runtime_engine = ""
          runtime_path = ""
          runtime_root = ""
          runtime_type = "io.containerd.runc.v2"

          [plugins."io.containerd.grpc.v1.cri".containerd.runtimes.runc.options]
            BinaryName = ""
            CriuImagePath = ""
            CriuPath = ""
            CriuWorkPath = ""
            IoGid = 0
            IoUid = 0
            NoNewKeyring = false
            NoPivotRoot = false
            Root = ""
            ShimCgroup = ""
            SystemdCgroup = false

      [plugins."io.containerd.grpc.v1.cri".containerd.untrusted_workload_runtime]
        base_runtime_spec = ""
        cni_conf_dir = ""
        cni_max_conf_num = 0
        container_annotations = []
        pod_annotations = []
        privileged_without_host_devices = false
        runtime_engine = ""
        runtime_path = ""
        runtime_root = ""
        runtime_type = ""

        [plugins."io.containerd.grpc.v1.cri".containerd.untrusted_workload_runtime.options]

    [plugins."io.containerd.grpc.v1.cri".image_decryption]
      key_model = "node"

    [plugins."io.containerd.grpc.v1.cri".registry]
      config_path = ""

      [plugins."io.containerd.grpc.v1.cri".registry.auths]

      [plugins."io.containerd.grpc.v1.cri".registry.configs]

      [plugins."io.containerd.grpc.v1.cri".registry.headers]

      [plugins."io.containerd.grpc.v1.cri".registry.mirrors]

    [plugins."io.containerd.grpc.v1.cri".x509_key_pair_streaming]
      tls_cert_file = ""
      tls_key_file = ""

  [plugins."io.containerd.internal.v1.opt"]
    path = "/opt/containerd"

  [plugins."io.containerd.internal.v1.restart"]
    interval = "10s"

  [plugins."io.containerd.internal.v1.tracing"]
    sampling_ratio = 1.0
    service_name = "containerd"

  [plugins."io.containerd.metadata.v1.bolt"]
    content_sharing_policy = "shared"

  [plugins."io.containerd.monitor.v1.cgroups"]
    no_prometheus = false

  [plugins."io.containerd.runtime.v1.linux"]
    no_shim = false
    runtime = "runc"
    runtime_root = ""
    shim = "containerd-shim"
    shim_debug = false

  [plugins."io.containerd.runtime.v2.task"]
    platforms = ["linux/amd64"]
    sched_core = false

  [plugins."io.containerd.service.v1.diff-service"]
    default = ["walking"]

  [plugins."io.containerd.service.v1.tasks-service"]
    rdt_config_file = ""

  [plugins."io.containerd.snapshotter.v1.aufs"]
    root_path = ""

  [plugins."io.containerd.snapshotter.v1.btrfs"]
    root_path = ""

  [plugins."io.containerd.snapshotter.v1.devmapper"]
    async_remove = false
    base_image_size = ""
    discard_blocks = false
    fs_options = ""
    fs_type = ""
    pool_name = ""
    root_path = ""

  [plugins."io.containerd.snapshotter.v1.native"]
    root_path = ""

  [plugins."io.containerd.snapshotter.v1.overlayfs"]
    root_path = ""
    upperdir_label = false

  [plugins."io.containerd.snapshotter.v1.zfs"]
    root_path = ""

  [plugins."io.containerd.tracing.processor.v1.otlp"]
    endpoint = ""
    insecure = false
    protocol = ""

[proxy_plugins]

[stream_processors]

  [stream_processors."io.containerd.ocicrypt.decoder.v1.tar"]
    accepts = ["application/vnd.oci.image.layer.v1.tar+encrypted"]
    args = ["--decryption-keys-path", "/etc/containerd/ocicrypt/keys"]
    env = ["OCICRYPT_KEYPROVIDER_CONFIG=/etc/containerd/ocicrypt/ocicrypt_keyprovider.conf"]
    path = "ctd-decoder"
    returns = "application/vnd.oci.image.layer.v1.tar"

  [stream_processors."io.containerd.ocicrypt.decoder.v1.tar.gzip"]
    accepts = ["application/vnd.oci.image.layer.v1.tar+gzip+encrypted"]
    args = ["--decryption-keys-path", "/etc/containerd/ocicrypt/keys"]
    env = ["OCICRYPT_KEYPROVIDER_CONFIG=/etc/containerd/ocicrypt/ocicrypt_keyprovider.conf"]
    path = "ctd-decoder"
    returns = "application/vnd.oci.image.layer.v1.tar+gzip"

[timeouts]
  "io.containerd.timeout.bolt.open" = "0s"
  "io.containerd.timeout.shim.cleanup" = "5s"
  "io.containerd.timeout.shim.load" = "5s"
  "io.containerd.timeout.shim.shutdown" = "3s"
  "io.containerd.timeout.task.state" = "2s"

[ttrpc]
  address = ""
  gid = 0
  uid = 0

2.2.2.6.2 替换默认配置文件

但上述配置文件后期改动的地方较多，这里直接换成可单机使用也可k8s环境使用的配置文件并配置好镜像加速器。

# vim /etc/containerd/config.toml

# cat /etc/containerd/config.toml
root = "/var/lib/containerd"
state = "/run/containerd"
oom_score = -999

[grpc]
  address = "/run/containerd/containerd.sock"
  uid = 0
  gid = 0
  max_recv_message_size = 16777216
  max_send_message_size = 16777216

[debug]
  address = ""
  uid = 0
  gid = 0
  level = ""

[metrics]
  address = ""
  grpc_histogram = false

[cgroup]
  path = ""

[plugins]
  [plugins.cgroups]
    no_prometheus = false
  [plugins.cri]
    stream_server_address = "127.0.0.1"
    stream_server_port = "0"
    enable_selinux = false
    sandbox_image = "easzlab/pause-amd64:3.2"
    stats_collect_period = 10
    systemd_cgroup = false
    enable_tls_streaming = false
    max_container_log_line_size = 16384
    [plugins.cri.containerd]
      snapshotter = "overlayfs"
      no_pivot = false
      [plugins.cri.containerd.default_runtime]
        runtime_type = "io.containerd.runtime.v1.linux"
        runtime_engine = ""
        runtime_root = ""
      [plugins.cri.containerd.untrusted_workload_runtime]
        runtime_type = ""
        runtime_engine = ""
        runtime_root = ""
    [plugins.cri.cni]
      bin_dir = "/opt/kube/bin"
      conf_dir = "/etc/cni/net.d"
      conf_template = "/etc/cni/net.d/10-default.conf"
    [plugins.cri.registry]
      [plugins.cri.registry.mirrors]
        [plugins.cri.registry.mirrors."docker.io"]
          endpoint = [
            "https://docker.mirrors.ustc.edu.cn",
            "http://hub-mirror.c.163.com"
          ]
        [plugins.cri.registry.mirrors."gcr.io"]
          endpoint = [
            "https://gcr.mirrors.ustc.edu.cn"
          ]
        [plugins.cri.registry.mirrors."k8s.gcr.io"]
          endpoint = [
            "https://gcr.mirrors.ustc.edu.cn/google-containers/"
          ]
        [plugins.cri.registry.mirrors."quay.io"]
          endpoint = [
            "https://quay.mirrors.ustc.edu.cn"
          ]
        [plugins.cri.registry.mirrors."harbor.kubemsb.com"] 此处添加了本地容器镜像仓库 Harbor,做为本地容器镜像仓库。
          endpoint = [
            "http://harbor.kubemsb.com"
          ]
    [plugins.cri.x509_key_pair_streaming]
      tls_cert_file = ""
      tls_key_file = ""
  [plugins.diff-service]
    default = ["walking"]
  [plugins.linux]
    shim = "containerd-shim"
    runtime = "runc"
    runtime_root = ""
    no_shim = false
    shim_debug = false
  [plugins.opt]
    path = "/opt/containerd"
  [plugins.restart]
    interval = "10s"
  [plugins.scheduler]
    pause_threshold = 0.02
    deletion_threshold = 0
    mutation_threshold = 100
    schedule_delay = "0s"
    startup_delay = "100ms"

2.2.2.7 启动containerd服务并设置开机自启动

# systemctl enable containerd
Created symlink from /etc/systemd/system/multi-user.target.wants/containerd.service to /usr/lib/systemd/system/containerd.service.
# systemctl start containerd

# systemctl status containerd
● containerd.service - containerd container runtime
   Loaded: loaded (/usr/lib/systemd/system/containerd.service; enabled; vendor preset: disabled)
   Active: active (running) since 五 2022-02-18 13:02:37 CST; 7s ago
     Docs: https://containerd.io
  Process: 60383 ExecStartPre=/sbin/modprobe overlay (code=exited, status=0/SUCCESS)
 Main PID: 60384 (containerd)
    Tasks: 8
   Memory: 20.0M
   CGroup: /system.slice/containerd.service
           └─60384 /usr/local/bin/containerd
           ......

2.2.2.8 复制ctr命令至系统

# ls usr/local/bin/
containerd  containerd-shim  containerd-shim-runc-v1  containerd-shim-runc-v2  containerd-stress  crictl  critest  ctd-decoder  ctr
# cp usr/local/bin/ctr /usr/bin/

2.2.2.9 查看已安装containerd服务版本

# ctr version
Client:
  Version:  v1.6.0
  Revision: 39259a8f35919a0d02c9ecc2871ddd6ccf6a7c6e
  Go version: go1.17.2

Server:
  Version:  v1.6.0
  Revision: 39259a8f35919a0d02c9ecc2871ddd6ccf6a7c6e
  UUID: c1972cbe-884a-41b0-867f-f8a58c168e6d

2.2.2.10 安装runC

由于二进制包中提供的runC默认需要系统中安装seccomp支持，需要单独安装，且不同版本runC对seccomp版本要求一致，所以建议单独下载runC 二进制包进行安装，里面包含了seccomp模块支持。

2.2.2.10.1 获取runC

使用wget下载
# wget https://github.com/opencontainers/runc/releases/download/v1.1.0/runc.amd64

2.2.2.10.2 安装runC并验证安装结果

查看已下载文件 
# ls
runc.amd64

安装runC
# mv runc.amd64 /usr/sbin/runc

为runC添加可执行权限
# chmod +x /usr/sbin/runc

使用runc命令验证是否安装成功
# runc -v
runc version 1.1.0
commit: v1.1.0-0-g067aaf85
spec: 1.0.2-dev
go: go1.17.6
libseccomp: 2.5.3

三、Containerd容器镜像管理

3.1 Containerd容器镜像管理命令

• docker使用docker images命令管理镜像
• 单机containerd使用ctr images命令管理镜像,containerd本身的CLI
• k8s中containerd使用crictl images命令管理镜像,Kubernetes社区的专用CLI工具

获取命令帮助
# ctr --help
NAME:
   ctr -
        __
  _____/ /______
 / ___/ __/ ___/
/ /__/ /_/ /
\___/\__/_/

containerd CLI


USAGE:
   ctr [global options] command [command options] [arguments...]

VERSION:
   v1.6.0

DESCRIPTION:

ctr is an unsupported debug and administrative client for interacting
with the containerd daemon. Because it is unsupported, the commands,
options, and operations are not guaranteed to be backward compatible or
stable from release to release of the containerd project.

COMMANDS:
   plugins, plugin            provides information about containerd plugins
   version                    print the client and server versions
   containers, c, container   manage containers
   content                    manage content
   events, event              display containerd events
   images, image, i           manage images
   leases                     manage leases
   namespaces, namespace, ns  manage namespaces
   pprof                      provide golang pprof outputs for containerd
   run                        run a container
   snapshots, snapshot        manage snapshots
   tasks, t, task             manage tasks
   install                    install a new package
   oci                        OCI tools
   shim                       interact with a shim directly
   help, h                    Shows a list of commands or help for one command

GLOBAL OPTIONS:
   --debug                      enable debug output in logs
   --address value, -a value    address for containerd's GRPC server (default: "/run/containerd/containerd.sock") [$CONTAINERD_ADDRESS]
   --timeout value              total timeout for ctr commands (default: 0s)
   --connect-timeout value      timeout for connecting to containerd (default: 0s)
   --namespace value, -n value  namespace to use with commands (default: "default") [$CONTAINERD_NAMESPACE]
   --help, -h                   show help
   --version, -v                print the version

获取命令帮助
# ctr images
NAME:
   ctr images - manage images

USAGE:
   ctr images command [command options] [arguments...]

COMMANDS:
   check                    check existing images to ensure all content is available locally
   export                   export images
   import                   import images
   list, ls                 list images known to containerd
   mount                    mount an image to a target path
   unmount                  unmount the image from the target
   pull                     pull an image from a remote
   push                     push an image to a remote
   delete, del, remove, rm  remove one or more images by reference
   tag                      tag an image
   label                    set and clear labels for an image
   convert                  convert an image

OPTIONS:
   --help, -h  show help

3.2 查看镜像

# ctr images ls
REF TYPE DIGEST SIZE PLATFORMS LABELS

3.3 下载镜像

containerd支持oci标准的镜像，所以可以直接使用docker官方或dockerfile构建的镜像

# ctr images pull --all-platforms docker.io/library/nginx:alpine

docker.io/library/nginx:alpine:                                                   resolved       |++++++++++++++++++++++++++++++++++++++|
docker.io/library/nginx:alpine:                                                   resolved       |++++++++++++++++++++++++++++++++++++++|
index-sha256:da9c94bec1da829ebd52431a84502ec471c8e548ffb2cedbf36260fd9bd1d4d3:    done           |++++++++++++++++++++++++++++++++++++++|
manifest-sha256:050385609d832fae11b007fbbfba77d0bba12bf72bc0dca0ac03e09b1998580f: done           |++++++++++++++++++++++++++++++++++++++|
layer-sha256:f2303c6c88653b9a6739d50f611c170b9d97d161c6432409c680f6b46a5f112f:    done           |++++++++++++++++++++++++++++++++++++++|
config-sha256:bef258acf10dc257d641c47c3a600c92f87be4b4ce4a5e4752b3eade7533dcd9:   done           |++++++++++++++++++++++++++++++++++++++|
layer-sha256:59bf1c3509f33515622619af21ed55bbe26d24913cedbca106468a5fb37a50c3:    done           |++++++++++++++++++++++++++++++++++++++|
layer-sha256:8d6ba530f6489d12676d7f61628427d067243ba4a3a512c3e28813b977cb3b0e:    done           |++++++++++++++++++++++++++++++++++++++|
layer-sha256:5288d7ad7a7f84bdd19c1e8f0abb8684b5338f3da86fe9ae1d7f0e9bc2de6595:    done           |++++++++++++++++++++++++++++++++++++++|
layer-sha256:39e51c61c033442d00c40a30b2a9ed01f40205875fbd8664c50b4dc3e99ad5cf:    done           |++++++++++++++++++++++++++++++++++++++|
layer-sha256:ee6f71c6f4a82b2afd01f92bdf6be0079364d03020e8a2c569062e1c06d3822b:    done           |++++++++++++++++++++++++++++++++++++++|
elapsed: 11.0s                                                                    total:  8.7 Mi (809.5 KiB/s)                                    
unpacking linux/amd64 sha256:da9c94bec1da829ebd52431a84502ec471c8e548ffb2cedbf36260fd9bd1d4d3...
done: 1.860946163s

说明：
这里ctr命令pull镜像时，不能直接把镜像名字写成`nginx:alpine`

查看已下载容器镜像
# ctr images ls
REF                            TYPE                                                      DIGEST                                                                  SIZE    PLATFORMS                                                                                LABELS
docker.io/library/nginx:alpine application/vnd.docker.distribution.manifest.list.v2+json sha256:da9c94bec1da829ebd52431a84502ec471c8e548ffb2cedbf36260fd9bd1d4d3 9.7 MiB linux/386,linux/amd64,linux/arm/v6,linux/arm/v7,linux/arm64/v8,linux/ppc64le,linux/s390x -

REF	TYPE	DIGEST
docker.io/library/nginx:alpine	application/vnd.docker.distribution.manifest.list.v2+json	sha256:da9c94bec1da829ebd52431a84502ec471c8e548ffb2cedbf36260fd9bd1d4d3

SIZE	PLATFORMS	LABELS
9.7 MiB	linux/386,linux/amd64,linux/arm/v6,linux/arm/v7,linux/arm64/v8,linux/ppc64le,linux/s390x	-

指定平台下载容器镜像
# ctr images pull --platform linux/amd64 docker.io/library/nginx:alpine

3.4 镜像挂载

方便查看镜像中包含的内容。

把已下载的容器镜像挂载至当前文件系统
# ctr images mount docker.io/library/nginx:alpine /mnt
sha256:af2fcce448e2e4451a5f4796a9bf9cb5c9b5f88e0d6d10029cada42fb9d268ac
/mnt
[root@localhost ~]# ls /mnt
bin  dev  docker-entrypoint.d  docker-entrypoint.sh  etc  home  lib  media  mnt  opt  proc  root  run  sbin  srv  sys  tmp  usr  var

卸载
# umount /mnt

3.5 镜像导出

把容器镜像导出
# ctr i export --all-platforms nginx.img docker.io/library/nginx:alpine

说明
--all-platforms,导出所有平台镜像，本版本为1.6版本，1.4版本不需要添加此选项。

查看已导出容器镜像
# ls
nginx.img

# ls -lh
总用量 196M

-rw-r--r--  1 root root  73M 2月  18 14:48 nginx.img

3.6 镜像删除

删除指定容器镜像
# ctr image rm docker.io/library/nginx:alpine
docker.io/library/nginx:alpine

再次查看容器镜像
[root@192 ~]# ctr images ls
REF TYPE DIGEST SIZE PLATFORMS LABELS

3.7 镜像导入

导入容器镜像
# ctr images import nginx.img
unpacking docker.io/library/nginx:alpine (sha256:da9c94bec1da829ebd52431a84502ec471c8e548ffb2cedbf36260fd9bd1d4d3)...done

3.8 修改镜像tag

# ctr images tag docker.io/library/nginx:alpine nginx:alpine
nginx:alpine

说明：
把docker.io/library/nginx:alpine 修改为 nginx:alpine

查看修改后的容器镜像
# ctr images ls
REF                            TYPE                                                      DIGEST                                                                  SIZE    PLATFORMS                                                                                LABELS
docker.io/library/nginx:alpine application/vnd.docker.distribution.manifest.list.v2+json sha256:da9c94bec1da829ebd52431a84502ec471c8e548ffb2cedbf36260fd9bd1d4d3 9.7 MiB linux/386,linux/amd64,linux/arm/v6,linux/arm/v7,linux/arm64/v8,linux/ppc64le,linux/s390x -
nginx:alpine                   application/vnd.docker.distribution.manifest.list.v2+json sha256:da9c94bec1da829ebd52431a84502ec471c8e548ffb2cedbf36260fd9bd1d4d3 9.7 MiB linux/386,linux/amd64,linux/arm/v6,linux/arm/v7,linux/arm64/v8,linux/ppc64le,linux/s390x -

修改后对容器镜像做检查比对
# ctr images check
REF                            TYPE                                                      DIGEST                                                                  STATUS         SIZE            UNPACKED
docker.io/library/nginx:alpine application/vnd.docker.distribution.manifest.list.v2+json sha256:da9c94bec1da829ebd52431a84502ec471c8e548ffb2cedbf36260fd9bd1d4d3 complete (7/7) 9.7 MiB/9.7 MiB true

nginx:alpine                   application/vnd.docker.distribution.manifest.list.v2+json sha256:da9c94bec1da829ebd52431a84502ec471c8e548ffb2cedbf36260fd9bd1d4d3 complete (7/7) 9.7 MiB/9.7 MiB true

四、Containerd容器管理

4.1 获取命令帮助

4.1.1 获取ctr命令帮助

[root@localhost ~]# ctr --help
NAME:
   ctr -
        __
  _____/ /______
 / ___/ __/ ___/
/ /__/ /_/ /
\___/\__/_/

containerd CLI


USAGE:
   ctr [global options] command [command options] [arguments...]

VERSION:
   v1.6.0

DESCRIPTION:

ctr is an unsupported debug and administrative client for interacting
with the containerd daemon. Because it is unsupported, the commands,
options, and operations are not guaranteed to be backward compatible or
stable from release to release of the containerd project.

COMMANDS:
   plugins, plugin            provides information about containerd plugins
   version                    print the client and server versions
   containers, c, container   manage containers
   content                    manage content
   events, event              display containerd events
   images, image, i           manage images
   leases                     manage leases
   namespaces, namespace, ns  manage namespaces
   pprof                      provide golang pprof outputs for containerd
   run                        run a container
   snapshots, snapshot        manage snapshots
   tasks, t, task             manage tasks
   install                    install a new package
   oci                        OCI tools
   shim                       interact with a shim directly
   help, h                    Shows a list of commands or help for one command

GLOBAL OPTIONS:
   --debug                      enable debug output in logs
   --address value, -a value    address for containerd's GRPC server (default: "/run/containerd/containerd.sock") [$CONTAINERD_ADDRESS]
   --timeout value              total timeout for ctr commands (default: 0s)
   --connect-timeout value      timeout for connecting to containerd (default: 0s)
   --namespace value, -n value  namespace to use with commands (default: "default") [$CONTAINERD_NAMESPACE]
   --help, -h                   show help
   --version, -v                print the version

4.1.2 获取创建静态容器命令帮助

# ctr container --help
NAME:
   ctr containers - manage containers

USAGE:
   ctr containers command [command options] [arguments...]

COMMANDS:
   create                   create container
   delete, del, remove, rm  delete one or more existing containers
   info                     get info about a container
   list, ls                 list containers
   label                    set and clear labels for a container
   checkpoint               checkpoint a container
   restore                  restore a container from checkpoint

OPTIONS:
   --help, -h  show help

说明：

使用`ctr container create `命令创建容器后，容器并没有处于运行状态，其只是一个静态的容器。这个 container 对象只是包含了运行一个容器所需的资源及配置的数据结构，例如： namespaces、rootfs 和容器的配置都已经初始化成功了，只是用户进程(本案例为nginx)还没有启动。需要使用`ctr tasks`命令才能获取一个动态容器。

4.1.3 获取动态容器命令帮助

# ctr run --help
NAME:
   ctr run - run a container

USAGE:
   ctr run [command options] [flags] Image|RootFS ID [COMMAND] [ARG...]
   
OPTIONS:
   --rm                                    remove the container after running
   --null-io                               send all IO to /dev/null
   --log-uri value                         log uri
   --detach, -d                            detach from the task after it has started execution
   --fifo-dir value                        directory used for storing IO FIFOs
   --cgroup value                          cgroup path (To disable use of cgroup, set to "" explicitly)
   --platform value                        run image for specific platform
   --cni                                   enable cni networking for the container
   --runc-binary value                     specify runc-compatible binary
   --runc-root value                       specify runc-compatible root
   --runc-systemd-cgroup                   start runc with systemd cgroup manager
   --uidmap container-uid:host-uid:length  run inside a user namespace with the specified UID mapping range; specified with the format container-uid:host-uid:length
   --gidmap container-gid:host-gid:length  run inside a user namespace with the specified GID mapping range; specified with the format container-gid:host-gid:length
   --remap-labels                          provide the user namespace ID remapping to the snapshotter via label options; requires snapshotter support
   --cpus value                            set the CFS cpu quota (default: 0)
   --cpu-shares value                      set the cpu shares (default: 1024)
   --snapshotter value                     snapshotter name. Empty value stands for the default value. [$CONTAINERD_SNAPSHOTTER]
   --snapshotter-label value               labels added to the new snapshot for this container.
   --config value, -c value                path to the runtime-specific spec config file
   --cwd value                             specify the working directory of the process
   --env value                             specify additional container environment variables (e.g. FOO=bar)
   --env-file value                        specify additional container environment variables in a file(e.g. FOO=bar, one per line)
   --label value                           specify additional labels (e.g. foo=bar)
   --mount value                           specify additional container mount (e.g. type=bind,src=/tmp,dst=/host,options=rbind:ro)
   --net-host                              enable host networking for the container
   --privileged                            run privileged container
   --read-only                             set the containers filesystem as readonly
   --runtime value                         runtime name (default: "io.containerd.runc.v2")
   --runtime-config-path value             optional runtime config path
   --tty, -t                               allocate a TTY for the container
   --with-ns value                         specify existing Linux namespaces to join at container runtime (format ':')
   --pid-file value                        file path to write the task's pid
   --gpus value                            add gpus to the container
   --allow-new-privs                       turn off OCI spec's NoNewPrivileges feature flag
   --memory-limit value                    memory limit (in bytes) for the container (default: 0)
   --device value                          file path to a device to add to the container; or a path to a directory tree of devices to add to the container
   --cap-add value                         add Linux capabilities (Set capabilities with 'CAP_' prefix)
   --cap-drop value                        drop Linux capabilities (Set capabilities with 'CAP_' prefix)
   --seccomp                               enable the default seccomp profile
   --seccomp-profile value                 file path to custom seccomp profile. seccomp must be set to true, before using seccomp-profile
   --apparmor-default-profile value        enable AppArmor with the default profile with the specified name, e.g. "cri-containerd.apparmor.d"
   --apparmor-profile value                enable AppArmor with an existing custom profile
   --rdt-class value                       name of the RDT class to associate the container with. Specifies a Class of Service (CLOS) for cache and memory bandwidth management.
   --rootfs                                use custom rootfs that is not managed by containerd snapshotter
   --no-pivot                              disable use of pivot-root (linux only)
   --cpu-quota value                       Limit CPU CFS quota (default: -1)
   --cpu-period value                      Limit CPU CFS period (default: 0)
   --rootfs-propagation value              set the propagation of the container rootfs

说明：
使用`ctr run`命令可以创建一个静态容器并使其运行。一步到位运行容器。

4.2 查看容器

container表示静态容器，可用c缩写代表container

# ctr container ls
CONTAINER    IMAGE    RUNTIME

或

# ctr c ls
CONTAINER    IMAGE    RUNTIME

4.3 查看任务

task表示容器里跑的进程, 可用t缩写代表task

# ctr task ls
TASK    PID    STATUS

或

# ctr t ls
TASK    PID    STATUS

4.4 创建静态容器

# ctr c create docker.io/library/nginx:alpine nginx1

# ctr container ls
CONTAINER    IMAGE                             RUNTIME
nginx1       docker.io/library/nginx:alpine    io.containerd.runc.v2

查看容器详细信息
# ctr container info nginx1

4.5 静态容器启动为动态容器

复制containerd连接runC垫片工具至系统
# ls usr/local/bin/
containerd  containerd-shim  containerd-shim-runc-v1  containerd-shim-runc-v2  containerd-stress  crictl  critest  ctd-decoder  ctr
[root@localhost ~]# cp usr/local/bin/containerd-shim-runc-v2 /usr/bin/

启动task，即表时在容器中运行了进程，即为动态容器。
# ctr task start -d nginx1
/docker-entrypoint.sh: /docker-entrypoint.d/ is not empty, will attempt to perform configuration
/docker-entrypoint.sh: Looking for shell scripts in /docker-entrypoint.d/

说明：
-d表示daemon或者后台的意思，否则会卡住终端

查看容器所在宿主机进程，是以宿主机进程的方式存在的。
# ctr task ls
TASK      PID     STATUS
nginx1    3395    RUNNING

查看容器的进程(都是物理机的进程)
# ctr task ps nginx1
PID     INFO
3395    -
3434    -

物理机查看到相应的进程
# ps -ef | grep 3395
root       3395   3375  0 19:16 ?        00:00:00 nginx: master process nginx -g daemon off;
101        3434   3395  0 19:16 ?        00:00:00 nginx: worker process

4.6 进入容器操作

# ctr task exec --exec-id 1 nginx1 /bin/sh

ifconfig 查看网卡信息
lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:65536  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)

curl 127.0.0.1 访问本地提供的web服务
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
  0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--     0<!DOCTYPE html>