这篇文章给大家分享的是有关docker中k8s认证及serviceaccount、RBAC的示例分析的内容。小编觉得挺实用的，因此分享给大家做个参考，一起跟随小编过来看看吧。
目前RBAC是k8s授权方式最常用的一种方式。
在k8s上，一个客户端向apiserver发起请求，需要如下信息：
1）username，uid，2) group,3) extra(额外信息)4) API5) request path,例如：http://127.0.0.1:8080/apis/apps/v1/namespaces/kube-system/d6）HTTP request action，如get,post,put,delete,7）Http request action，如 get,list,create,udate,patch,watch,proxy,redirect,delete,deletecollection8） Rresource9）Subresource10）Namespace11）API group K8s可以支持多版本并存。
其实，我们用kubectl向apiserver发起的命令，都是http方式的。
k8s验证分为useraccount和serviceaccount。
可以用代理：
[root@master ~]# kubectl proxy --port=8080[root@master ~]# curl [root@master ~]# kubectl get deploy -n kube-systemNAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGEcoredns 2 2 2 2 20d[root@master ~]# curl http://127.0.0.1:8080/apis/apps/v1/namespaces/kube-system/deployments[root@master ~]# kubectl get svcNAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGEkubernetes ClusterIP 10.96.0.1 <none> 443/TCP 20d[root@master ~]# kubectl describe svc kubernetesName: kubernetesNamespace: defaultLabels: component=apiserver provider=kubernetesAnnotations: <none>Selector: <none>Type: ClusterIPIP: 10.96.0.1Port: https 443/TCPTargetPort: 6443/TCPEndpoints: 172.16.1.100:6443Session Affinity: NoneEvents: <none> 上面我们看到10.96.0.1是kubernetes apiserver的地址，从而实现了集群外部通过10.96.0.1访问集群内部的pod，同时也实现了集群内部的pod访问集群外部的应用的功能。
只要访问apiserver，就必须实现认证。而认证信息是存储在pod中的。
[root@master ~]# kubectl explain pods.spec.serviceAccountName[root@master manifests]# kubectl create serviceaccount mysa -o yaml --dry-run > mysa.yaml[root@master manifests]# cat mysa.yaml apiVersion: v1kind: ServiceAccountmetadata: creationTimestamp: null name: mysa 上面我们可以看到，只要是kubectl create的，只要加上-o yaml，就可以导出清单文件，这样我们以后就不用从头到尾写清单文件了，而是只要生产一个，然后改改就行了，这个很不错。
另外kubectl get 也可以导出yaml格式的，如下：
[root@master manifests]# kubectl get pods myapp-1 -o yaml --exportapiVersion: v1kind: Podmetadata: creationTimestamp: null generateName: myapp- labels: app: myapp-pod controller-revision-hash: myapp-8598dd746f statefulset.kubernetes.io/pod-name: myapp-1 ownerReferences: - apiVersion: apps/v1 blockOwnerDeletion: true controller: true kind: StatefulSet name: myapp uid: a98ebc48-c24f-11e8-bb35-005056a24ecb selfLink: /api/v1/namespaces/default/pods/myapp-1spec: containers: - image: ikubernetes/myapp:v1 imagePullPolicy: IfNotPresent name: myapp ports: - containerPort: 80 name: web protocol: TCP resources: {} terminationMessagePath: /dev/termination-log terminationMessagePolicy: File volumeMounts: - mountPath: /usr/share/nginx/html name: myappdata - mountPath: /var/run/secrets/kubernetes.io/serviceaccount name: default-token-5r85r readOnly: true dnsPolicy: ClusterFirst hostname: myapp-1 nodeName: node2 priority: 0 restartPolicy: Always schedulerName: default-scheduler securityContext: {} serviceAccount: default serviceAccountName: default subdomain: myapp-svc terminationGracePeriodSeconds: 30 tolerations: - effect: NoExecute key: node.kubernetes.io/not-ready operator: Exists tolerationSeconds: 300 - effect: NoExecute key: node.kubernetes.io/unreachable operator: Exists tolerationSeconds: 300 volumes: - name: myappdata persistentVolumeClaim: claimName: myappdata-myapp-1 - name: default-token-5r85r secret: defaultMode: 420 secretName: default-token-5r85rstatus: phase: Pending qosClass: BestEffort将上面的改改就成为我们新的配置清单了。
创建service account
[root@master manifests]# kubectl create serviceaccount adminserviceaccount/admin created[root@master manifests]# kubectl get saNAME SECRETS AGEadmin 1 2sdefault 1 20d[root@master manifests]# kubectl describe sa adminName: adminNamespace: defaultLabels: <none>Annotations: <none>Image pull secrets: <none>Mountable secrets: admin-token-6jpc5Tokens: admin-token-6jpc5Events: <none>[root@master manifests]# kubectl get secretNAME TYPE DATA AGEadmin-token-6jpc5 kubernetes.io/service-account-token 3 57s 看到自动就会多一个token。
下面我们用配置清单把serviceaccount和pod绑定起来。
[root@master manifests]# cat pod-sa-demo.yaml apiVersion: v1kind: Podmetadata: name: pod-sa-demo namespace: default labels: app: myapp tier: frontend annotations: zhixin.com/created-by: "cluster admin"spec: containers: - name: myapp image: ikubernetes/myapp:v1 ports: - name: http containerPort: 80 serviceAccountName: admin #这表示我们这个pod使用自定义的验证信息admin[root@master manifests]# kubectl apply -f pod-sa-demo.yaml pod/pod-sa-demo created创建useraccount
kubeconfig是客户端连接apiserver时使用的认证格式的配置文件。
[root@master manifests]# kubectl config view apiVersion: v1clusters:- cluster: certificate-authority-data: REDACTED server: https://172.16.1.100:6443 name: kubernetescontexts:- context: #context定义了哪个集群用哪个用户来访问。 cluster: kubernetes user: kubernetes-admin name: kubernetes-admin@kubernetescurrent-context: kubernetes-admin@kuberneteskind: Configpreferences: {}users:- name: kubernetes-admin user: client-certificate-data: REDACTED client-key-data: REDACTED 证书存放位置：
[root@master manifests]# cd /etc/kubernetes/pki/[root@master pki]# lsapiserver.crt apiserver.key ca.crt front-proxy-ca.crt front-proxy-client.keyapiserver-etcd-client.crt apiserver-kubelet-client.crt ca.key front-proxy-ca.key sa.keyapiserver-etcd-client.key apiserver-kubelet-client.key etcd front-proxy-client.crt sa.pub 例子：
1、做一个私钥
[root@master pki]# cd /etc/kubernetes/pki[root@master pki]# (umask 077; openssl genrsa -out zhixin.key 2048)Generating RSA private key, 2048 bit long modulus...........+++...........+++e is 65537 (0x10001) 括号是子shell的意思。
2、基于私钥生成一个证书
CN就是用户的账户名字。
[root@master pki]# openssl req -new -key zhixin.key -out zhixin.csr -subj "/CN=zhixin"-subj:替换或指定证书申请者的个人信息
3、签证书
[root@master pki]# openssl x509 -req -in zhixin.csr -CA ca.crt -CAkey ca.key -CAcreateserial -out zhixin.crt -days 365Signature oksubject=/CN=zhixinGetting CA Private Key -days：表示证书的过期时间
x509:生成x509格式证书
4、查看证书内容
[root@master pki]# openssl x509 -in zhixin.crt -text -nooutCertificate: Data: Version: 1 (0x0) Serial Number: ab:45:1b:b3:92:32:59:ae Signature Algorithm: sha256WithRSAEncryption Issuer: CN=kubernetes #证书签署人 Validity #有效期限 Not Before: Sep 28 08:01:20 2018 GMT Not After : Sep 28 08:01:20 2019 GMT Subject: CN=zhixin #一会用这个账户登录k8s Subject Public Key Info: Public Key Algorithm: rsaEncryption Public-Key: (2048 bit) Modulus: 00:bf:e5:b1:80:1a:a6:d1:24:ca:b8:75:a1:71:08: d2:ba:43:ee:53:a1:10:b5:7a:83:e7:8b:06:65:c7: 8a:07:02:ca:cc:8f:5c:94:a9:7a:10:24:f6:41:a0: c6:fe:5f:21:59:21:e7:72:30:12:38:89:85:78:54: c1:15:c4:13:33:43:9c:94:c0:dc:99:e9:f0:44:7e: 35:66:cd:e0:d9:0c:82:dc:b3:73:ee:ea:47:9e:5e: e5:bf:0b:45:fb:a3:cf:59:67:ae:13:31:9c:dc:b6: 78:da:b2:7e:c0:7e:c2:30:c5:fd:ea:6f:94:fa:81: 19:9f:71:9c:cf:60:07:5b:fa:0d:c0:6f:2c:b4:e0: 42:d6:6d:d3:39:23:2b:f7:ad:cc:21:f8:df:89:ff: 6e:45:59:1f:5d:db:aa:fa:07:ef:fc:b3:7e:3d:b1: dd:3e:be:5e:43:de:8f:e2:ea:aa:ec:6c:48:df:2f: 2e:20:61:e3:5c:6a:37:3e:2b:32:e5:1a:ad:35:88: d6:d2:db:aa:26:5d:cb:67:0a:65:9e:d4:79:76:92: 9a:41:fb:df:db:85:1a:ea:5e:ff:bb:7b:2f:01:10: 9f:8e:9c:a1:fe:ae:ac:9d:43:02:40:01:f7:d6:da: bf:5a:99:ba:d0:bf:ea:53:1e:f5:51:06:9c:ac:6f: 32:43 Exponent: 65537 (0x10001) Signature Algorithm: sha256WithRSAEncryption 91:43:cd:36:ad:88:17:a1:81:9f:8f:ad:9b:c5:41:d7:de:aa: 6a:f0:3a:00:f2:d7:9b:0e:89:bc:51:73:cc:4f:10:85:13:70: aa:d1:67:f8:f3:a1:6b:83:ff:99:76:7f:14:a5:b4:82:fb:1b: fb:cf:d5:fc:b0:2f:ff:68:c4:b1:c0:ee:f9:6b:41:ea:0a:96: 2f:55:1d:d7:77:f8:70:a6:15:a4:b6:e7:6d:93:61:2e:ac:7a: 10:70:fa:f7:43:da:56:f2:d0:e9:6b:01:72:73:2d:65:ea:4d: c4:3b:46:2d:1b:ad:f8:1f:eb:71:88:35:51:2a:dc:3a:36:fe: 63:bb:28:ee:d2:a0:d4:e0:14:95:10:96:20:2e:f3:75:12:eb: 05:8e:34:a1:dc:74:19:a5:76:0f:f2:bd:f3:56:aa:c9:40:51: c7:bd:1f:1f:c1:ec:a5:98:c8:b8:1d:07:67:fa:1c:a0:a3:1f: d3:ba:cb:09:52:9a:e7:59:39:ce:c8:ef:01:c2:4b:98:ff:05: 12:bf:69:36:0e:a6:a9:f6:40:34:28:36:0d:1b:76:31:b4:96: 6e:09:33:8e:d5:0a:96:77:dd:41:b3:29:db:d5:5e:fa:05:f7: e7:90:5d:79:6d:a9:59:20:60:0f:fe:d5:b6:38:6c:1a:ee:51: 66:c3:9b:4b 5、把用户账户信息添加到k8s集群中
[root@master pki]# kubectl config set-credentials zhixin --client-certificate=zhixin.crt --client-key=zhixin.key --embed-certs=trueUser "zhixin" set.embed-certs：表示把用户信息隐藏起来。
5、设置context上下文，指定zhixin用户访问k8s的哪个集群
[root@master pki]# kubectl config viewapiVersion: v1clusters:- cluster: certificate-authority-data: REDACTED server: https://172.16.1.100:6443 name: kubernetescontexts:- context: cluster: kubernetes user: kubernetes-admin name: kubernetes-admin@kubernetescurrent-context: kubernetes-admin@kuberneteskind: Configpreferences: {}users:- name: kubernetes-admin user: client-certificate-data: REDACTED client-key-data: REDACTED- name: zhixin user: client-certificate-data: REDACTED client-key-data: REDACTED[root@master pki]# kubectl config set-context zhixin@kubernetes --cluster=kubernetes --user=zhixinContext "zhixin@kubernetes" created.[root@master pki]# kubectl config viewapiVersion: v1clusters:- cluster: certificate-authority-data: REDACTED server: https://172.16.1.100:6443 name: kubernetescontexts:- context: cluster: kubernetes user: kubernetes-admin name: kubernetes-admin@kubernetes- context: cluster: kubernetes user: zhixin name: zhixin@kubernetescurrent-context: kubernetes-admin@kuberneteskind: Configpreferences: {}users:- name: kubernetes-admin user: client-certificate-data: REDACTED client-key-data: REDACTED- name: zhixin user: client-certificate-data: REDACTED client-key-data: REDACTED 上面看到contexts里面有zhixin的名字了。
6、切换到zhixin用户登录k8s
[root@master pki]# kubectl config use-context zhixin@kubernetesSwitched to context "zhixin@kubernetes".[root@master pki]# kubectl get podsNo resources found.Error from server (Forbidden): pods is forbidden: User "zhixin" cannot list pods in the namespace "default" 上面看到get pods时报错了，这是因为用户zhixin@kubernetes没有管理器权限。
7、切回k8s管理员
[root@master pki]# kubectl config use-context kubernetes-admin@kubernetesSwitched to context "kubernetes-admin@kubernetes". 8、设置新的k8s集群
[root@master ~]# kubectl config set-cluster mycluster --kubeconfig=/tmp/test.conf --server="https://127.0.0.1:6443" --certificate-authority=/etc/kubernetes/pki/ca.crt --embed-certs=trueCluster "mycluster" set.--kubeconfig：指定认证文件位置，不指定的话默认就在~/.kube/config
--embed-certs=true 表示证书信息被隐藏
大家看到，我们上面就创建了一个新的k8s集群叫mycluster。
[root@master ~]# kubectl config view --kubeconfig=/tmp/test.conf apiVersion: v1clusters:- cluster: certificate-authority-data: REDACTED server: https://127.0.0.1:6443 name: myclustercontexts: []current-context: ""kind: Configpreferences: {}users: []RBAC（基于角色的访问控制）
rbac:role based ac，也就是我们把用户加入角色里面，这样用户就具有角色的权限了。
在k8s中，一切皆对象。
Object_URL: /apis/<GROUP>/<VERSION>/namespaces/<NAMESPACE_NAME>/<KIND>[OJJECT_ID]
RBAC是通过rolebinding把user绑定到role上的。而role是基于namespace设定的，也就是这说这个user只能访问指定namespace下的pod资源。
而如果把user通过clusterrolebind绑定到clusterrole上后，那么这个user就突破了namespace的限制，而拥有了集群级别的权限，即这个用户可以访问这个集群下所有namespace下的pod了。
但是，我们也可以用rolebinding去把user绑定到clusterrole。在上图中，我们把user1通过rolebinding绑定到clusterrole上，但是我们知道rolebinding只限制在namespace中，所以user1也只限定在namespace中，而不是整个集群中。
[root@master ~]# kubectl create role pods-reader --verb=get,list,watch --resource=pods注意：想要授予所有权限可以用*来表示[root@master ~]# kubectl create role pods-reader --verb=get,list,watch --resource=pods --dry-run -o yamlapiVersion: rbac.authorization.k8s.io/v1kind: Rolemetadata: creationTimestamp: null name: pods-readerrules:- apiGroups: - "" resources: - pods verbs: - get - list - watch[root@master ~]# kubectl get roleNAME AGEpods-reader 7s[root@master ~]# kubectl describe role pods-readerName: pods-readerLabels: <none>Annotations: <none>PolicyRule: Resources Non-Resource URLs Resource Names Verbs --------- ----------------- -------------- ----- pods [] [] [get list watch][root@master ~]# kubectl create rolebinding zhixin-read-pods --role=pods-reader --user=zhixinrolebinding.rbac.authorization.k8s.io/zhixin-read-pods created[root@master ~]# kubectl create rolebinding zhixin-read-pods --role=pods-reader --user=zhixin -o yaml --dry-runapiVersion: rbac.authorization.k8s.io/v1kind: RoleBindingmetadata: creationTimestamp: null name: zhixin-read-podsroleRef: apiGroup: rbac.authorization.k8s.io kind: Role name: pods-readersubjects: #就是引用的用户- apiGroup: rbac.authorization.k8s.io kind: User name: zhixin[root@master ~]# kubectl explain rolebinding[root@master ~]# kubectl describe rolebinding zhixin-read-podsName: zhixin-read-podsLabels: <none>Annotations: <none>Role: Kind: Role Name: pods-readerSubjects: Kind Name Namespace ---- ---- --------- User zhixin[root@master ~]# kubectl config use-context zhixin@kubernetesSwitched to context "zhixin@kubernetes".[root@master ~]# kubectl get podsNAME READY STATUS RESTARTS AGEclient 0/1 Error 0 18dfilebeat-ds-bn7wf 0/1 InvalidImageName 0 4dfilebeat-ds-vd287 0/1 InvalidImageName 0 3dliveness-httpget-pod 1/1 Running 7 11dmyapp-0 1/1 Running 0 23h 上面我们看到先前我们建立的zhixin用户是没有get pods权限的，但是我这回把它加入了pods-reader role，也就拥有了pods-reader role的权限。
[root@master ~]# kubectl get pods -n kube-systemNo resources found.Error from server (Forbidden): pods is forbidden: User "zhixin" cannot list pods in the namespace "kube-system 但是，zhixin用户就没有访问kube-system权限，因为role就没有访问这个名称空间的权限，而只有访问default名称空间的权限。
rolebinding只对namespace有效。
我们再切换回到管理员。
[root@master ~]# kubectl config use-context kubernetes-admin@kubernetesSwitched to context "kubernetes-admin@kubernetes".下面我们再定义一个clusterrole。
[root@master ~]# kubectl create clusterrole cluster-reader --verb=get,list,watch --resource=podsclusterrole.rbac.authorization.k8s.io/cluster-reader created[root@master ~]# kubectl create clusterrole cluster-reader --verb=get,list,watch --resource=pods -o yaml --dry-runapiVersion: rbac.authorization.k8s.io/v1kind: ClusterRolemetadata: creationTimestamp: null name: cluster-readerrules:- apiGroups: - "" resources: - pods verbs: - get - list - watch[root@master ~]# kubectl explain clusterrole[root@master ~]# kubectl get rolebindingNAME AGEzhixin-read-pods 46m[root@master ~]# kubectl delete rolebinding zhixin-read-podsrolebinding.rbac.authorization.k8s.io "zhixin-read-pods" deleted 下面我们测试把用户zhixin加入clusterrole里面：
[root@master ~]# kubectl create clusterrolebinding zhixin-read-all-pods --clusterrole=cluster-reader --user=zhixin clusterrolebinding.rbac.authorization.k8s.io/zhixin-read-all-pods created[root@master ~]# kubectl get clusterrolebinding |grep readzhixin-read-all-pods 2m[root@master ~]# kubectl describe clusterrolebinding zhixin-read-all-podsName: zhixin-read-all-podsLabels: <none>Annotations: <none>Role: Kind: ClusterRole Name: cluster-readerSubjects: Kind Name Namespace ---- ---- --------- User zhixin[root@master ~]# kubectl config use-context zhixin@kubernetesSwitched to context "zhixin@kubernetes".[root@master ~]# kubectl get podsNAME READY STATUS RESTARTS AGEclient 0/1 Error 0 18dfilebeat-ds-bn7wf 0/1 InvalidImageName 0 4d[root@master ~]# kubectl get pods -n kube-systemNAME READY STATUS RESTARTS AGEcoredns-78fcdf6894-2l2cf 1/1 Running 17 21dcoredns-78fcdf6894-dkkfq 1/1 Running 16 21d 可见，我们把用户zhixin绑定到clusterrole后，这个 用户对所有的名称空间都有权限了。因为cluserrolebinding是针对集群的，而rolebinding是只针对namespace的。
下面我们再测试一个，把用户用rolebinding绑定到cluserrole里面，看是什么效果：
[root@master ~]# kubectl config use-context kubernetes-admin@kubernetesSwitched to context "kubernetes-admin@kubernetes".[root@master ~]# kubectl delete clusterrolebinding zhixin-read-all-podsclusterrolebinding.rbac.authorization.k8s.io "zhixin-read-all-pods" deleted[root@master ~]# kubectl create rolebinding zhixin-read-pods --clusterrole=cluster-reader --user=zhixin rolebinding.rbac.authorization.k8s.io/zhixin-read-pods created[root@master ~]# kubectl describe rolebinding zhixin-read-podsName: zhixin-read-podsLabels: <none>Annotations: <none>Role: Kind: ClusterRole Name: cluster-readSubjects: Kind Name Namespace ---- ---- --------- User zhixin[root@master ~]# kubectl config use-context zhixin@kubernetesSwitched to context "zhixin@kubernetes".[root@master ~]# kubectl get podsNAME READY STATUS RESTARTS AGEclient 0/1 Error 0 18dfilebeat-ds-bn7wf 0/1 InvalidImageName 0 4dfilebeat-ds-vd287 0/1 InvalidImageName 0 3dliveness-httpget-pod 1/1 Running 7 11d[root@master ~]# kubectl get pods -n kube-systemNo resources found.Error from server (Forbidden): pods is forbidden: User "zhixin" cannot list pods in the namespace "kube-system"可以看出，clusterrole用rolebinding绑定后，会被降级到rolebinding所在的namespace里面。
[root@master ~]# kubectl get clusterrole admin -o yaml resources: - pods - pods/attach - pods/exec - pods/portforward - pods/proxy verbs: - create - delete - deletecollection - get - list - patch - update - watch[root@master ~]# kubectl create rolebinding default-nameespace-admin --clusterrole=adin --user=zhixinrolebinding.rbac.authorization.k8s.io/default-nameespace-admin created 这样，我们就把zhixin设置为default名称空间的管理员，而不是其他名称空间的管理员。这就是用rolebinding绑定clusterrole的功能。
[root@master ~]# kubectl get clusterrolebinding cluster-admin -o yaml- apiGroup: rbac.authorization.k8s.io kind: Group name: system:masters[root@master pki]# openssl x509 -in ./apiserver-kubelet-client.crt -text -noout Subject: O=system:masters, CN=kube-apiserver-kubelet-client 看到system:masters组具有管理员权限
感谢各位的阅读！关于“docker中k8s认证及serviceaccount、RBAC的示例分析”这篇文章就分享到这里了，希望以上内容可以对大家有一定的帮助，让大家可以学到更多知识，如果觉得文章不错，可以把它分享出去让更多的人看到吧！
