CentOS7使用tar方式安装Containerd，配置文件介绍

主机：centos 7.9

下载

官网GitHub上下载地址：https://github.com/containerd/containerd/releases

问题：
创建容器后，运行的时候报错：

# ctr -n k8s.io task start -d busybox
ctr: failed to create shim: OCI runtime create failed: unable to retrieve OCI runtime error (open /run/containerd/io.containerd.runtime.v2.task/k8s.io/busybox/log.json: no such file or directory): runc did not terminate successfully: exit status 127: unknown

通过运行runc命令排查，发现缺少依赖：seccomp_api_get
但是centos7.9系统已经安装libseccomp-devel了，再次检查发现，seccomp_api_get对libseccomp版本有要求，至少libseccomp v2.4版本才提供的有seccomp_api_get，安装的版本是v2.3的，不带这个 (软件包 libseccomp-devel-2.3.1-4.el7.x86_64 已安装并且是最新版本)

# runc
runc: symbol lookup error: runc: undefined symbol: seccomp_api_get

网上下载v2.4b版本的，地址：https://rpmfind.net/linux/rpm2html/search.php?query=libseccomp

centos7.9系统使用的最高版本就是v2.3了

换个其他网站：https://pkgs.org/download/libseccomp

估计只能源码编译安装v2.4版本的了

首先需要安装 seccomp 依赖：yum install -y libseccomp-devel (版本v2.3，后续使用创建容器的时候有问题)

由于 containerd 需要调用 runc，所以我们也需要先安装 runc，不过 containerd 提供了一个包含相关依赖的压缩包 cri-containerd-cni-${VERSION}.${OS}-${ARCH}.tar.gz，可以直接使用这个包来进行安装。
首先从 release 页面下载最新版本的压缩包，当前为 1.5.9 版本：

# wget https://github.com/containerd/containerd/releases/download/v${VERSION}/cri-containerd-cni-${VERSION}-linux-amd64.tar.gz
# tar --no-overwrite-dir -C / -xzf cri-containerd-cni-${VERSION}-linux-amd64.tar.gz

wget https://github.com/containerd/containerd/releases/download/v1.5.9/cri-containerd-cni-1.5.9-linux-amd64.tar.gz

# 不用下载containerd-1.5.9-linux-amd64.tar.gz

查看压缩包里的内容

# tar -tf containerd-1.5.9-linux-amd64.tar.gz
bin/
bin/ctr
bin/containerd-shim-runc-v2
bin/containerd-shim-runc-v1
bin/containerd-shim
bin/containerd

# 可以通过 tar 的 -t 选项直接看到压缩包中包含哪些文件：
# tar -tf cri-containerd-cni-1.5.9-linux-amd64.tar.gz
etc/
etc/crictl.yaml
etc/systemd/
etc/systemd/system/
etc/systemd/system/containerd.service
etc/cni/
etc/cni/net.d/
etc/cni/net.d/10-containerd-net.conflist
usr/
usr/local/
usr/local/bin/
usr/local/bin/ctr
usr/local/bin/containerd-shim-runc-v2
usr/local/bin/containerd-shim-runc-v1
usr/local/bin/containerd-stress
usr/local/bin/containerd-shim
usr/local/bin/ctd-decoder
usr/local/bin/containerd
usr/local/bin/crictl
usr/local/bin/critest
usr/local/sbin/
usr/local/sbin/runc
opt/
opt/containerd/
opt/containerd/cluster/
opt/containerd/cluster/version
opt/containerd/cluster/gce/
opt/containerd/cluster/gce/cni.template
opt/containerd/cluster/gce/env
opt/containerd/cluster/gce/cloud-init/
opt/containerd/cluster/gce/cloud-init/node.yaml
opt/containerd/cluster/gce/cloud-init/master.yaml
opt/containerd/cluster/gce/configure.sh
opt/cni/
opt/cni/bin/
opt/cni/bin/bandwidth
opt/cni/bin/host-local
opt/cni/bin/static
opt/cni/bin/portmap
opt/cni/bin/vlan
opt/cni/bin/flannel
opt/cni/bin/tuning
opt/cni/bin/ipvlan
opt/cni/bin/ptp
opt/cni/bin/bridge
opt/cni/bin/host-device
opt/cni/bin/macvlan
opt/cni/bin/vrf
opt/cni/bin/sbr
opt/cni/bin/dhcp
opt/cni/bin/loopback
opt/cni/bin/firewall

安装

# 直接将压缩包解压到系统的各个目录中：
tar --no-overwrite-dir -C / -xzf cri-containerd-cni-1.5.9-linux-amd64.tar.gz

# 将 /usr/local/bin 和 /usr/local/sbin 追加到 ~/.bashrc 文件的 PATH 环境变量中，然后执行下面的命令使其立即生效：(这一步在该系统中不用操作，默认这俩路径已经在PATH 环境变量中了)
export PATH=$PATH:/usr/local/bin:/usr/local/sbin
source ~/.bashrc

生成配置文件

# containerd 的默认配置文件为 /etc/containerd/config.toml，我们可以通过如下所示的命令生成一个默认的配置：
mkdir /etc/containerd
containerd config default > /etc/containerd/config.toml

启动

# containerd 压缩包中包含一个 etc/systemd/system/containerd.service 的文件，这样我们就可以通过 systemd 来配置 containerd 作为守护进程运行了，内容如下所示：
cat /etc/systemd/system/containerd.service

[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

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

这里有两个重要的参数：

• Delegate: 这个选项允许 containerd 以及运行时自己管理自己创建容器的 cgroups。如果不设置这个选项，systemd 就会将进程移到自己的 cgroups 中，从而导致 containerd 无法正确获取容器的资源使用情况。
• KillMode: 这个选项用来处理 containerd 进程被杀死的方式。默认情况下，systemd 会在进程的 cgroup 中查找并杀死 containerd 的所有子进程。KillMode 字段可以设置的值如下。
  • control-group（默认值）：当前控制组里面的所有子进程，都会被杀掉
  • process：只杀主进程
  • mixed：主进程将收到 SIGTERM 信号，子进程收到 SIGKILL 信号
  • none：没有进程会被杀掉，只是执行服务的 stop 命令

要将 KillMode 的值设置为 process，这样可以确保升级或重启 containerd 时不杀死现有的容器。（不用设置，默认就是process）

启动 containerd 了，直接执行下面的命令即可：

systemctl daemon-reload
systemctl start containerd

启动完成后就可以使用 containerd 的本地 CLI 工具 ctr 了，比如查看版本：

# ctr version
Client:
  Version:  v1.5.9
  Revision: 1407cab509ff0d96baa4f0eb6ff9980270e6e620
  Go version: go1.16.12

Server:
  Version:  v1.5.9
  Revision: 1407cab509ff0d96baa4f0eb6ff9980270e6e620
  UUID: 91a37754-a44f-4152-96b6-f2f7f96194f6

配置文件说明

首先来查看下上面默认生成的配置文件 /etc/containerd/config.toml：

# cat config.toml
disabled_plugins = []
imports = []
oom_score = 0
plugin_dir = ""
required_plugins = []
root = "/var/lib/containerd"
state = "/run/containerd"
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_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"]
    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
    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:3.5"
    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 = ""
      max_conf_num = 1

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

      [plugins."io.containerd.grpc.v1.cri".containerd.default_runtime]
        base_runtime_spec = ""
        container_annotations = []
        pod_annotations = []
        privileged_without_host_devices = false
        runtime_engine = ""
        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 = ""
          container_annotations = []
          pod_annotations = []
          privileged_without_host_devices = false
          runtime_engine = ""
          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 = ""
        container_annotations = []
        pod_annotations = []
        privileged_without_host_devices = false
        runtime_engine = ""
        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.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"]

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

  [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 = ""
    pool_name = ""
    root_path = ""

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

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

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

[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.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

这个配置文件比较复杂，我们可以将重点放在其中的 plugins 配置上面，仔细观察我们可以发现每一个顶级配置块的命名都是 plugins."io.containerd.xxx.vx.xxx" 这种形式，每一个顶级配置块都表示一个插件，其中 io.containerd.xxx.vx 表示插件的类型，vx 后面的 xxx 表示插件的 ID，我们可以通过 ctr 查看插件列表：

# ctr plugin ls
TYPE                            ID                       PLATFORMS      STATUS    
io.containerd.content.v1        content                  -              ok        
io.containerd.snapshotter.v1    aufs                     linux/amd64    skip      
io.containerd.snapshotter.v1    btrfs                    linux/amd64    skip      
io.containerd.snapshotter.v1    devmapper                linux/amd64    error     
io.containerd.snapshotter.v1    native                   linux/amd64    ok        
io.containerd.snapshotter.v1    overlayfs                linux/amd64    ok        
io.containerd.snapshotter.v1    zfs                      linux/amd64    skip      
io.containerd.metadata.v1       bolt                     -              ok        
io.containerd.differ.v1         walking                  linux/amd64    ok        
io.containerd.gc.v1             scheduler                -              ok        
io.containerd.service.v1        introspection-service    -              ok        
io.containerd.service.v1        containers-service       -              ok        
io.containerd.service.v1        content-service          -              ok        
io.containerd.service.v1        diff-service             -              ok        
io.containerd.service.v1        images-service           -              ok        
io.containerd.service.v1        leases-service           -              ok        
io.containerd.service.v1        namespaces-service       -              ok        
io.containerd.service.v1        snapshots-service        -              ok        
io.containerd.runtime.v1        linux                    linux/amd64    ok        
io.containerd.runtime.v2        task                     linux/amd64    ok        
io.containerd.monitor.v1        cgroups                  linux/amd64    ok        
io.containerd.service.v1        tasks-service            -              ok        
io.containerd.internal.v1       restart                  -              ok        
io.containerd.grpc.v1           containers               -              ok        
io.containerd.grpc.v1           content                  -              ok        
io.containerd.grpc.v1           diff                     -              ok        
io.containerd.grpc.v1           events                   -              ok        
io.containerd.grpc.v1           healthcheck              -              ok        
io.containerd.grpc.v1           images                   -              ok        
io.containerd.grpc.v1           leases                   -              ok        
io.containerd.grpc.v1           namespaces               -              ok        
io.containerd.internal.v1       opt                      -              ok        
io.containerd.grpc.v1           snapshots                -              ok        
io.containerd.grpc.v1           tasks                    -              ok        
io.containerd.grpc.v1           version                  -              ok        
io.containerd.grpc.v1           cri                      linux/amd64    ok        

顶级配置块下面的子配置块表示该插件的各种配置，比如 cri 插件下面就分为 containerd、cni 和 registry 的配置，而 containerd 下面又可以配置各种 runtime，还可以配置默认的 runtime。比如现在我们要为镜像配置一个加速器，那么就需要在 cri 配置块下面的 registry 配置块下面进行配置 registry.mirrors：

# 修改之前

    [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]

# 修改之后
    [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".registry.mirrors."docker.io"]
          endpoint = ["https://bqr1dr1n.mirror.aliyuncs.com"]
        [plugins."io.containerd.grpc.v1.cri".registry.mirrors."k8s.gcr.io"]
          endpoint = ["https://registry.aliyuncs.com/k8sxio"]

• registry.mirrors."xxx": 表示需要配置 mirror 的镜像仓库，例如 registry.mirrors."docker.io" 表示配置 docker.io 的 mirror。
• endpoint: 表示提供 mirror 的镜像加速服务，比如我们可以注册一个阿里云的镜像服务来作为 docker.io 的 mirror。

另外在默认配置中还有两个关于存储的配置路径：

root = "/var/lib/containerd"
state = "/run/containerd"

其中 root 是用来保存持久化数据，包括 Snapshots, Content, Metadata 以及各种插件的数据，每一个插件都有自己单独的目录，Containerd 本身不存储任何数据，它的所有功能都来自于已加载的插件。
而另外的 state 是用来保存运行时的临时数据的，包括 sockets、pid、挂载点、运行时状态以及不需要持久化的插件数据。

替换 containerd 默认的 sand_box 镜像，编辑 /etc/containerd/config.toml

# sandbox_image = "k8s.gcr.io/pause:3.5"
sandbox_image = "registry.aliyuncs.com/google_containers/pause:3.2"

# 重启
systemctl restart containerd