使用 kubeadm 部署 kubernetes(CRI 使用 containerd)

kubeadm 提供了 kubeadm init 以及 kubeadm join 这两个命令作为快速创建 kubernetes 集群的最佳实践。

安装 containerd

参考 安装 Docker 一节添加 apt/yum 源,之后执行如下命令。

# debian 系
$ sudo apt install containerd.io
# rhel 系
$ sudo yum install containerd.io

配置 containerd

新建 /etc/systemd/system/cri-containerd.service 文件

[Unit]
Description=containerd container runtime for kubernetes
Documentation=https://containerd.io
After=network.target local-fs.target
[Service]
ExecStartPre=-/sbin/modprobe overlay
ExecStart=/usr/bin/containerd --config //etc/cri-containerd/config.toml
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

新建 /etc/cri-containerd/config.toml containerd 配置文件

version = 2
# persistent data location
root = "/var/lib/cri-containerd"
# runtime state information
state = "/run/cri-containerd"
plugin_dir = ""
disabled_plugins = []
required_plugins = []
# set containerd's OOM score
oom_score = 0
[grpc]
address = "/run/cri-containerd/cri-containerd.sock"
tcp_address = ""
tcp_tls_cert = ""
tcp_tls_key = ""
# socket uid
uid = 0
# socket gid
gid = 0
max_recv_message_size = 16777216
max_send_message_size = 16777216
[debug]
address = ""
format = "json"
uid = 0
gid = 0
level = ""
[metrics]
address = "127.0.0.1:1338"
grpc_histogram = false
[cgroup]
path = ""
[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"
[plugins]
[plugins."io.containerd.gc.v1.scheduler"]
pause_threshold = 0.02
deletion_threshold = 0
mutation_threshold = 100
schedule_delay = "0s"
startup_delay = "100ms"
[plugins."io.containerd.grpc.v1.cri"]
disable_tcp_service = true
stream_server_address = "127.0.0.1"
stream_server_port = "0"
stream_idle_timeout = "4h0m0s"
enable_selinux = false
selinux_category_range = 1024
sandbox_image = "registry.cn-hangzhou.aliyuncs.com/google_containers/pause:3.5"
stats_collect_period = 10
# systemd_cgroup = false
enable_tls_streaming = false
max_container_log_line_size = 16384
disable_cgroup = false
disable_apparmor = false
restrict_oom_score_adj = false
max_concurrent_downloads = 3
disable_proc_mount = false
unset_seccomp_profile = ""
tolerate_missing_hugetlb_controller = true
disable_hugetlb_controller = true
ignore_image_defined_volumes = false
[plugins."io.containerd.grpc.v1.cri".containerd]
snapshotter = "overlayfs"
default_runtime_name = "runc"
no_pivot = false
disable_snapshot_annotations = false
discard_unpacked_layers = false
[plugins."io.containerd.grpc.v1.cri".containerd.runtimes]
[plugins."io.containerd.grpc.v1.cri".containerd.runtimes.runc]
runtime_type = "io.containerd.runc.v2"
pod_annotations = []
container_annotations = []
privileged_without_host_devices = false
base_runtime_spec = ""
[plugins."io.containerd.grpc.v1.cri".containerd.runtimes.runc.options]
# SystemdCgroup enables systemd cgroups.
SystemdCgroup = true
# BinaryName is the binary name of the runc binary.
# BinaryName = "runc"
# BinaryName = "crun"
# NoPivotRoot disables pivot root when creating a container.
# NoPivotRoot = false
# NoNewKeyring disables new keyring for the container.
# NoNewKeyring = false
# ShimCgroup places the shim in a cgroup.
# ShimCgroup = ""
# IoUid sets the I/O's pipes uid.
# IoUid = 0
# IoGid sets the I/O's pipes gid.
# IoGid = 0
# Root is the runc root directory.
Root = ""
# CriuPath is the criu binary path.
# CriuPath = ""
# CriuImagePath is the criu image path
# CriuImagePath = ""
# CriuWorkPath is the criu work path.
# CriuWorkPath = ""
[plugins."io.containerd.grpc.v1.cri".cni]
bin_dir = "/opt/cni/bin"
conf_dir = "/etc/cni/net.d"
max_conf_num = 1
conf_template = ""
[plugins."io.containerd.grpc.v1.cri".registry]
config_path = "/etc/cri-containerd/certs.d"
[plugins."io.containerd.grpc.v1.cri".registry.headers]
# Foo = ["bar"]
[plugins."io.containerd.grpc.v1.cri".image_decryption]
key_model = ""
[plugins."io.containerd.grpc.v1.cri".x509_key_pair_streaming]
tls_cert_file = ""
tls_key_file = ""
[plugins."io.containerd.internal.v1.opt"]
path = "/opt/cri-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.v2.task"]
platforms = ["linux/amd64"]
[plugins."io.containerd.service.v1.diff-service"]
default = ["walking"]
[plugins."io.containerd.snapshotter.v1.devmapper"]
root_path = ""
pool_name = ""
base_image_size = ""
async_remove = false

安装 kubelet kubeadm kubectl cri-tools kubernetes-cni

Ubuntu/Debian

$ apt-get update && apt-get install -y apt-transport-https
$ curl https://mirrors.aliyun.com/kubernetes/apt/doc/apt-key.gpg | apt-key add -
$ cat <<EOF | sudo tee /etc/apt/sources.list.d/kubernetes.list
deb https://mirrors.aliyun.com/kubernetes/apt/ kubernetes-xenial main
EOF
$ apt-get update
$ apt-get install -y kubelet kubeadm kubectl

CentOS/Fedora

$ cat <<EOF | sudo tee /etc/yum.repos.d/kubernetes.repo
[kubernetes]
name=Kubernetes
baseurl=https://mirrors.aliyun.com/kubernetes/yum/repos/kubernetes-el7-x86_64/
enabled=1
gpgcheck=1
repo_gpgcheck=1
gpgkey=https://mirrors.aliyun.com/kubernetes/yum/doc/yum-key.gpg https://mirrors.aliyun.com/kubernetes/yum/doc/rpm-package-key.gpg
EOF
$ sudo yum install -y kubelet kubeadm kubectl

修改内核的运行参数

$ cat <<EOF | sudo tee /etc/sysctl.d/99-kubernetes-cri.conf
net.bridge.bridge-nf-call-iptables = 1
net.ipv4.ip_forward = 1
net.bridge.bridge-nf-call-ip6tables = 1
EOF
# 应用配置
$ sysctl --system

配置 kubelet

修改 kubelet.service

/etc/systemd/system/kubelet.service.d/10-proxy-ipvs.conf 写入以下内容

# 启用 ipvs 相关内核模块
[Service]
ExecStartPre=-/sbin/modprobe ip_vs
ExecStartPre=-/sbin/modprobe ip_vs_rr
ExecStartPre=-/sbin/modprobe ip_vs_wrr
ExecStartPre=-/sbin/modprobe ip_vs_sh

执行以下命令应用配置。

$ sudo systemctl daemon-reload

部署

master

$ systemctl enable cri-containerd
$ systemctl start cri-containerd
$ sudo kubeadm init \
--image-repository registry.cn-hangzhou.aliyuncs.com/google_containers \
--pod-network-cidr 10.244.0.0/16 \
--cri-socket /run/cri-containerd/cri-containerd.sock \
--v 5 \
--ignore-preflight-errors=all
  • --pod-network-cidr 10.244.0.0/16 参数与后续 CNI 插件有关,这里以 flannel 为例,若后续部署其他类型的网络插件请更改此参数。

执行可能出现错误,例如缺少依赖包,根据提示安装即可。

执行成功会输出

...
[addons] Applied essential addon: CoreDNS
I1116 12:35:13.270407 86677 request.go:538] Throttling request took 181.409184ms, request: POST:https://192.168.199.100:6443/api/v1/namespaces/kube-system/serviceaccounts
I1116 12:35:13.470292 86677 request.go:538] Throttling request took 186.088112ms, request: POST:https://192.168.199.100:6443/api/v1/namespaces/kube-system/configmaps
[addons] Applied essential addon: kube-proxy
Your Kubernetes control-plane has initialized successfully!
To start using your cluster, you need to run the following as a regular user:
mkdir -p $HOME/.kube
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config
You should now deploy a pod network to the cluster.
Run "kubectl apply -f [podnetwork].yaml" with one of the options listed at:
https://kubernetes.io/docs/concepts/cluster-administration/addons/
Then you can join any number of worker nodes by running the following on each as root:
kubeadm join 192.168.199.100:6443 --token cz81zt.orsy9gm9v649e5lf \
--discovery-token-ca-cert-hash sha256:5edb316fd0d8ea2792cba15cdf1c899a366f147aa03cba52d4e5c5884ad836fe

node 工作节点

另一主机 重复 部署 小节以前的步骤,安装配置好 kubelet。根据提示,加入到集群。

$ systemctl enable cri-containerd
$ systemctl start cri-containerd
$ kubeadm join 192.168.199.100:6443 \
--token cz81zt.orsy9gm9v649e5lf \
--discovery-token-ca-cert-hash sha256:5edb316fd0d8ea2792cba15cdf1c899a366f147aa03cba52d4e5c5884ad836fe \
--cri-socket /run/cri-containerd/cri-containerd.sock

查看服务

所有服务启动后,通过 crictl 查看本地实际运行的容器。这些服务大概分为三类:主节点服务、工作节点服务和其它服务。

CONTAINER_RUNTIME_ENDPOINT=/run/cri-containerd/cri-containerd.sock crictl ps -a

主节点服务

  • apiserver 是整个系统的对外接口,提供 RESTful 方式供客户端和其它组件调用;

  • scheduler 负责对资源进行调度,分配某个 pod 到某个节点上;

  • controller-manager 负责管理控制器,包括 endpoint-controller(刷新服务和 pod 的关联信息)和 replication-controller(维护某个 pod 的复制为配置的数值)。

工作节点服务

  • proxy 为 pod 上的服务提供访问的代理。

其它服务

  • Etcd 是所有状态的存储数据库;

使用

/etc/kubernetes/admin.conf 复制到 ~/.kube/config

执行 $ kubectl get all -A 查看启动的服务。

由于未部署 CNI 插件,CoreDNS 未正常启动。如何使用 Kubernetes,请参考后续章节。

部署 CNI

这里以 flannel 为例进行介绍。

flannel

检查 podCIDR 设置

$ kubectl get node -o yaml | grep CIDR
# 输出
podCIDR: 10.244.0.0/16
podCIDRs:
$ kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/v0.11.0/Documentation/kube-flannel.yml

master 节点默认不能运行 pod

如果用 kubeadm 部署一个单节点集群,默认情况下无法使用,请执行以下命令解除限制

$ kubectl taint nodes --all node-role.kubernetes.io/master-
# 恢复默认值
# $ kubectl taint nodes NODE_NAME node-role.kubernetes.io/master=true:NoSchedule

参考文档