第一章、什么是server account
Service account是为了方便Pod里面的进程调用Kubernetes API或其他外部服务而设计的。它与User account不同 1.User account是为人设计的，而service account则是为Pod中的进程调用Kubernetes API而设计； 2.User account是跨namespace的，而service account则是仅局限它所在的namespace； 3.每个namespace都会自动创建一个default service account 4.Token controller检测service account的创建，并为它们创建secret 5.开启ServiceAccount Admission Controller后 1.每个Pod在创建后都会自动设置spec.serviceAccount为default（除非指定了其他ServiceAccout） 2.验证Pod引用的service account已经存在，否则拒绝创建 3.如果Pod没有指定ImagePullSecrets，则把service account的ImagePullSecrets加到Pod中 4.每个container启动后都会挂载该service account的token和ca.crt到/var/run/secrets/kubernetes.io/serviceaccount/
验证：
[root@k8s-master01 ~]# kubectl create namespace qiangungun #创建一个名称空间 namespace "qiangungun" created [root@k8s-master01 ~]# kubectl get sa -n qiangungun #名称空间创建完成后会自动创建一个sa NAME SECRETS AGE default 1 11s [root@k8s-master01 ~]# kubectl get secret -n qiangungun #同时也会自动创建一个secret NAME TYPE DATA AGE default-token-5jtz2 kubernetes.io/service-account-token 3 19s
在创建的名称空间中新建一个pod
[root@k8s-master01 pod-example]# cat pod_demo.yaml kind: Pod apiVersion: v1 metadata: name: task-pv-pod namespace: qiangungun spec: containers: - name: nginx image: ikubernetes/myapp:v1 ports: - containerPort: 80 name: www
查看pod信息
[root@k8s-master01 pod-example]# kubectl apply -f pod_demo.yaml pod "task-pv-pod" created [root@k8s-master01 pod-example]# kubectl get pod -n qiangungun NAME READY STATUS RESTARTS AGE task-pv-pod 1/1 Running 0 13s [root@k8s-master01 pod-example]# kubectl get pod task-pv-pod -o yaml -n qiangungun ...... volumeMounts: - mountPath: /var/run/secrets/kubernetes.io/serviceaccount name: default-token-5jtz2 ...... volumes: #挂载sa的secret - name: default-token-5jtz2 secret: defaultMode: 420 secretName: default-token-5jtz2 ......
#名称空间新建的pod如果不指定sa，会自动挂载当前名称空间中默认的sa(default)
第二章、创建serviceaccount(以下简称sa)
[root@k8s-master01 ~]# kubectl create serviceaccount admin #创建一个sa 名称为admin serviceaccount "admin" created [root@k8s-master01 ~]# kubectl get sa NAME SECRETS AGE admin 1 6s default 1 28d [root@k8s-master01 ~]# kubectl describe sa admin #查看名称为admin的sa的信息，系统会自动创建一个token信息 Name: admin Namespace: default Labels: <none> Annotations: <none> Image pull secrets: <none> Mountable secrets: admin-token-rxtrc Tokens: admin-token-rxtrc Events: <none> [root@k8s-master01 ~]# kubectl get secret #会自动创建一个secret(admin-token-rxtrc),用于当前sa连接至当前API server时使用的认证信息 NAME TYPE DATA AGE admin-token-rxtrc kubernetes.io/service-account-token 3 1m default-token-tcwjz kubernetes.io/service-account-token 3 28d myapp-ingress-secret kubernetes.io/tls 2 6h mysql-passwd Opaque 1 17d tomcat-ingress-secret kubernetes.io/tls 2 7h
创建一个pod应用刚刚创建的sa
[root@k8s-master01 service_account]# cat deploy-demon.yaml apiVersion: v1 kind: Pod metadata: name: sa-demo labels: app: myapp release: canary spec: containers: - name: myapp image: ikubernetes/myapp:v2 ports: - name: httpd containerPort: 80 serviceAccountName: admin #此处指令为指定sa的名称 [root@k8s-master01 service_account]# kubectl apply -f deploy-demon.yaml pod "sa-demo" created [root@k8s-master01 service_account]# kubectl describe pod sa-demo ...... Mounts: /var/run/secrets/kubernetes.io/serviceaccount from admin-token-rxtrc (ro) #pod会自动挂载自己sa的证书 ......
Volumes:
admin-token-rxtrc:
Type: Secret (a volume populated by a Secret)
SecretName: admin-token-rxtrc
......
集群交互的时候少不了的是身份认证，使用 kubeconfig（即证书） 和 token 两种认证方式是最简单也最通用的认证方式，下面我使用kubeconfing来进行认证
使用kubeconfig文件来组织关于集群，用户，名称空间和身份验证机制的信息。使用 kubectl命令行工具对kubeconfig文件来查找选择群集并与群集的API服务器进行通信所需的信息。
默认情况下 kubectl使用的配置文件名称是在$HOME/.kube目录下 config文件，可以通过设置环境变量KUBECONFIG或者--kubeconfig指定其他的配置文件
查看系统的kubeconfig
[root@k8s-master01 ~]# kubectl config view apiVersion: v1 clusters: #集群列表 - cluster: certificate-authority-data: REDACTED #认证集群的方式 server: https://172.16.150.212:6443 #访问服务的APIserver的路径
name: kubernetes #集群的名称 contexts: #上下文列表 - context: cluster: kubernetes #访问kubernetes这个集群 user: kubernetes-admin #使用 kubernetes-admin账号 name: kubernetes-admin@kubernetes #给定一个名称 current-context: kubernetes-admin@kubernetes #当前上下文，表示使用哪个账号访问哪个集群 kind: Config preferences: {} users: #用户列表 - name: kubernetes-admin #用户名称 user: client-certificate-data: REDACTED #客户端证书，用于与apiserver进行认证 client-key-data: REDACTED #客户端私钥
[root@k8s-master01 ~]# kubectl get svc NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 29d my-nginx NodePort 10.104.13.148 <none> 80:32008/TCP 18h myapp ClusterIP 10.102.229.150 <none> 80/TCP 19h tomcat ClusterIP 10.106.222.72 <none> 8080/TCP,8009/TCP 19h [root@k8s-master01 ~]# kubectl describe svc kubernetes Name: kubernetes Namespace: default Labels: component=apiserver provider=kubernetes Annotations: <none> Selector: <none> Type: ClusterIP IP: 10.96.0.1 Port: https 443/TCP TargetPort: 6443/TCP Endpoints: 172.16.150.212:6443 #可以看到此处svc后端的Endpoint是当前节点的IP地址，通过svc的IP地址进行映射，以确保cluster中的pod可以通过该sa与集群内api进行通讯，仅仅是身份认证 Session Affinity: ClientIP Events: <none>
查看kubeconfig命令行配置帮助
[root@k8s-master01 ~]# kubectl config --help Modify kubeconfig files using subcommands like "kubectl config set current-context my-context" The loading order follows these rules: 1. If the --kubeconfig flag is set, then only that file is loaded. The flag may only be set once and no merging takes place. 2. If $KUBECONFIG environment variable is set, then it is used a list of paths (normal path delimitting rules for your system). These paths are merged. When a value is modified, it is modified in the file that defines the stanza. When a value is created, it is created in the first file that exists. If no files in the chain exist, then it creates the last file in the list. 3. Otherwise, ${HOME}/.kube/config is used and no merging takes place. Available Commands: current-context 显示 current_context delete-cluster 删除 kubeconfig 文件中指定的集群 delete-context 删除 kubeconfig 文件中指定的 context get-clusters 显示 kubeconfig 文件中定义的集群 get-contexts 描述一个或多个 contexts rename-context Renames a context from the kubeconfig file. set 设置 kubeconfig 文件中的一个单个值 set-cluster 设置 kubeconfig 文件中的一个集群条目 set-context 设置 kubeconfig 文件中的一个 context 条目 set-credentials 设置 kubeconfig 文件中的一个用户条目 unset 取消设置 kubeconfig 文件中的一个单个值 use-context 设置 kubeconfig 文件中的当前上下文 view 显示合并的 kubeconfig 配置或一个指定的 kubeconfig 文件 Usage: kubectl config SUBCOMMAND [options] Use "kubectl <command> --help" for more information about a given command. Use "kubectl options" for a list of global command-line options (applies to all commands).
第三章、创建一个cluster用户及context
使用当前系统的ca证书认证一个私有证书
[root@k8s-master01 ~]# cd /etc/kubernetes/pki/ [root@k8s-master01 pki]# (umask 077;openssl genrsa -out qiangungun.key 2048) Generating RSA private key, 2048 bit long modulus .........................+++ ..........................................................+++ e is 65537 (0x10001) [root@k8s-master01 pki]# openssl req -new -key qiangungun.key -out qiangungun.csr -subj "/CN=qiangungun" #qiangungun是后面我们创建的用户名称，需要保持一致 [root@k8s-master01 pki]# openssl x509 -req -in qiangungun.csr -CA ca.crt -CAkey ca.key -CAcreateserial -out qiangungun.crt -days 3650 Signature ok subject=/CN=qiangungun Getting CA Private Key
查看证书内容
[root@k8s-master01 pki]# openssl x509 -in qiangungun.crt -text -noout Certificate: Data: Version: 1 (0x0) Serial Number: b6:06:cb:30:86:e3:fe:84 Signature Algorithm: sha256WithRSAEncryption Issuer: CN=kubernetes #由谁签署的 Validity #证书的有效时间 Not Before: Nov 27 15:09:41 2018 GMT Not After : Nov 24 15:09:41 2028 GMT Subject: CN=qiangungun #证书使用的用户 Subject Public Key Info: Public Key Algorithm: rsaEncryption Public-Key: (2048 ......
创建一个当前集群用户
[root@k8s-master01 pki]# kubectl config set-credentials qiangungun --client-certificate=./qiangungun.crt --client-key=./qiangungun.key --embed-certs=true User "qiangungun" set. [root@k8s-master01 pki]# kubectl config view apiVersion: v1 clusters: - cluster: certificate-authority-data: REDACTED server: https://172.16.150.212:6443
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: REDACTED client-key-data: REDACTED
- name: qiangungun #我们新建的用户 user: client-certificate-data: REDACTED client-key-data: REDACTED
为qiangungun用户创建一个context
[root@k8s-master01 pki]# kubectl config set-context qiangungun@kubernetes --cluster=kubernetes --user=qiangungun Context "qiangungun@kubernetes" created. [root@k8s-master01 pki]# kubectl config view apiVersion: v1 clusters: - cluster: certificate-authority-data: REDACTED server: https://172.16.150.212:6443
name: kubernetes contexts: - context: cluster: kubernetes user: kubernetes-admin name: kubernetes-admin@kubernetes - context: #新创建的context cluster: kubernetes user: qiangungun name: qiangungun@kubernetes current-context: kubernetes-admin@kubernetes kind: Config preferences: {} users: - name: kubernetes-admin user: client-certificate-data: REDACTED client-key-data: REDACTED- name: qiangungun user: client-certificate-data: REDACTED client-key-data: REDACTED
切换serviceaccount
[root@k8s-master01 pki]# kubectl config use-context qiangungun@kubernetes Switched to context "qiangungun@kubernetes". [root@k8s-master01 pki]# kubectl get pod Error from server (Forbidden): pods is forbidden: User "qiangungun" cannot list pods in the namespace "default"
自定义一个cluster
[root@k8s-master01 pki]# kubectl config set-cluster mycluster --kubeconfig=/tmp/test.conf --server="https://172.16.150.212:6443" --certificate-authority=/etc/kubernetes/pki/ca.crt --embed-certs=true Cluster "mycluster" set. [root@k8s-master01 pki]# kubectl config view --kubeconfig=/tmp/test.conf apiVersion: v1 clusters: - cluster: certificate-authority-data: REDACTED server: https://172.16.150.212:6443
name: mycluster contexts: [] current-context: "" kind: Config preferences: {} users: []