Kubernetes探秘—配置文件目录结构

Kubernetes的配置目录包括/etc/kubernetes、/home/supermap/.kube和/var/lib/kubelet目录。

下面我们来看一看，这些目录里到底有些什么文件（操作系统使用Ubuntu 18.04LTS desktop）。

安装tree命令：

sudo apt  install tree

1、kubernetes主配置目录

显示/etc/kubernetes目录结构：

supermap@podc01:/etc/kubernetes$ tree .
.
├── admin.conf
├── controller-manager.conf
├── kubelet.conf
├── manifests
│   ├── etcd.yaml
│   ├── kube-apiserver.yaml
│   ├── kube-controller-manager.yaml
│   └── kube-scheduler.yaml
├── pki
│   ├── apiserver.crt
│   ├── apiserver-etcd-client.crt
│   ├── apiserver-etcd-client.key
│   ├── apiserver.key
│   ├── apiserver-kubelet-client.crt
│   ├── apiserver-kubelet-client.key
│   ├── ca.crt
│   ├── ca.key
│   ├── etcd
│   │   ├── ca.crt
│   │   ├── ca.key
│   │   ├── healthcheck-client.crt
│   │   ├── healthcheck-client.key
│   │   ├── peer.crt
│   │   ├── peer.key
│   │   ├── server.crt
│   │   └── server.key
│   ├── front-proxy-ca.crt
│   ├── front-proxy-ca.key
│   ├── front-proxy-client.crt
│   ├── front-proxy-client.key
│   ├── sa.key
│   └── sa.pub
├── scheduler.conf
└── tmp [error opening dir]

4 directories, 30 files

2、kubernetes用户配置目录

主用户目录下的隐藏目录.kube包含用户的配置参数和缓存数据。目录结构为：

/home/supermap/.kube
├── cache
│   └── discovery
│       ├── 10.1.1.181_6443
│       └── 10.1.1.201_6443
├── config
└── http-cache
    ├── 028d83935e12ce471cbe29f4096ef4ed

其中，配置文件config的内容为：

apiVersion: v1
clusters:
- cluster:
    certificate-authority-data: LS0tLS1CRUdJTiBDRVJUSUZJQ0FURS0tLS0t...
    server: https://10.1.1.201:6443
  name: kubernetes
contexts:
- context:
    cluster: kubernetes
    user: kubernetes-admin
  name: kubernetes-admin@kubernetes
current-context: kubernetes-admin@kubernetes
kind: Config
preferences: {}
users:
- name: kubernetes-admin
  user:
    client-certificate-data: LS0tLS1CRUdJTiBDRVJUSUZJQ0FURS0tLS0tCk1...
    client-key-data: LS0tLS1CRUdJTiBSU0EgUFJJVkFURSBLRVktLS0tLQpNSUl...

3、kubelet服务的配置目录

每一个ks节点都需要运行kubelet服务。kubelet服务的配置在/var/lib/kubelet目录下：

supermap@podc01:/var/lib/kubelet$ tree
.
├── config.yaml
├── cpu_manager_state
├── device-plugins
│   ├── DEPRECATION
│   ├── kubelet_internal_checkpoint
│   └── kubelet.sock
├── kubeadm-flags.env
├── pki
│   ├── kubelet-client-2018-11-23-10-08-12.pem
│   ├── kubelet-client-2018-11-23-10-08-38.pem
│   ├── kubelet-client-current.pem -> /var/lib/kubelet/pki/kubelet-client-2018-11-23-10-08-38.pem
│   ├── kubelet.crt
│   └── kubelet.key
├── plugin-containers [error opening dir]
├── plugins [error opening dir]
├── plugins_registry [error opening dir]
├── pod-resources [error opening dir]
└── pods [error opening dir]

7 directories, 11 files

4、kubelet.service服务目录

kubelet使用systemd管理，service定义文件位于： /lib/systemd/system/kubelet.service。

最新的dropin文件位于： /etc/systemd/system/kubelet.service.d，内容为：

supermap@podc01:/etc/systemd/system/kubelet.service.d$ cat 10-kubeadm.conf 
# Note: This dropin only works with kubeadm and kubelet v1.11+
[Service]
Environment="KUBELET_KUBECONFIG_ARGS=--bootstrap-kubeconfig=/etc/kubernetes/bootstrap-kubelet.conf --kubeconfig=/etc/kubernetes/kubelet.conf"

Environment="KUBELET_CONFIG_ARGS=--config=/var/lib/kubelet/config.yaml"

# This is a file that "kubeadm init" and "kubeadm join" generates at runtime, populating the KUBELET_KUBEADM_ARGS variable dynamically
EnvironmentFile=-/var/lib/kubelet/kubeadm-flags.env

# This is a file that the user can use for overrides of the kubelet args as a last resort. Preferably, the user should use
# the .NodeRegistration.KubeletExtraArgs object in the configuration files instead. KUBELET_EXTRA_ARGS should be sourced from this file.
EnvironmentFile=-/etc/default/kubelet

ExecStart=
ExecStart=/usr/bin/kubelet $KUBELET_KUBECONFIG_ARGS $KUBELET_CONFIG_ARGS $KUBELET_KUBEADM_ARGS $KUBELET_EXTRA_ARGS

可以看到，在新的kubernetes配置结构中，这个kublet服务参数的配置有了很大的变化。启动参数不再放在kubelet.service文件里了，放到了/var/lib/kubelet、/etc/default/kubelet。

注意，这个变化可能会导致以前的很多手动安装的脚本工具不再可用。