K8S之存储Secret概述与类型说明，并详解常用Secret示例

主机配置规划

Secret概述

Secret解决了密码、token、秘钥等敏感数据的配置问题，而不需要把这些敏感数据暴露到镜像或者Pod Spec中。Secret可以以Volume或者环境变量的方式使用。

用户可以创建 secret，同时系统也创建了一些 secret。

要使用 secret，pod 需要引用 secret。Pod 可以用两种方式使用 secret：作为 volume 中的文件被挂载到 pod 中的一个或者多个容器里，或者当 kubelet 为 pod 拉取镜像时使用。

Secret类型

• Service Account：用来访问Kubernetes API，由Kubernetes自动创建，并且会自动挂载到Pod的 /run/secrets/kubernetes.io/serviceaccount 目录中。
• Opaque：base64编码格式的Secret，用来存储密码、秘钥等。
• kubernetes.io/dockerconfigjson：用来存储私有docker registry的认证信息。

Service Account

通过kube-proxy查看

 1 [root@k8s-master ~]# kubectl get pod -A | grep 'kube-proxy' 
 2 kube-system            kube-proxy-6bfh7                             1/1     Running   12         7d3h
 3 kube-system            kube-proxy-6vfkf                             1/1     Running   11         7d3h
 4 kube-system            kube-proxy-bvl9n                             1/1     Running   11         7d3h
 5 [root@k8s-master ~]# 
 6 [root@k8s-master ~]# kubectl exec -it -n kube-system kube-proxy-6bfh7 -- /bin/sh 
 7 # ls -l /run/secrets/kubernetes.io/serviceaccount
 8 total 0
 9 lrwxrwxrwx 1 root root 13 Jun  8 13:39 ca.crt -> ..data/ca.crt
10 lrwxrwxrwx 1 root root 16 Jun  8 13:39 namespace -> ..data/namespace
11 lrwxrwxrwx 1 root root 12 Jun  8 13:39 token -> ..data/token

Opaque Secret

创建secret

手动加密，基于base64加密

1 [root@k8s-master ~]# echo -n 'admin' | base64
2 YWRtaW4=
3 [root@k8s-master ~]# echo -n '1f2d1e2e67df' | base64
4 MWYyZDFlMmU2N2Rm

yaml文件

 1 [root@k8s-master secret]# pwd
 2 /root/k8s_practice/secret
 3 [root@k8s-master secret]# cat secret.yaml 
 4 apiVersion: v1
 5 kind: Secret
 6 metadata:
 7   name: mysecret
 8 type: Opaque
 9 data:
10   username: YWRtaW4=
11   password: MWYyZDFlMmU2N2Rm

或者通过如下命令行创建【secret名称故意设置不一样，以方便查看对比】，生成secret后会自动加密，而非明文存储。

kubectl create secret generic db-user-pass --from-literal=username=admin --from-literal=password=1f2d1e2e67df

生成secret，并查看状态

 1 [root@k8s-master secret]# kubectl apply -f secret.yaml 
 2 secret/mysecret created
 3 [root@k8s-master secret]# 
 4 [root@k8s-master secret]# kubectl get secret   ### 查看默认名称空间的secret简要信息
 5 NAME                  TYPE                                  DATA   AGE
 6 basic-auth            Opaque                                1      2d12h
 7 default-token-v48g4   kubernetes.io/service-account-token   3      27d
 8 mysecret              Opaque                                2      23s  ### 可见已创建
 9 tls-secret            kubernetes.io/tls                     2      3d2h
10 [root@k8s-master secret]# 
11 [root@k8s-master secret]# kubectl get secret mysecret -o yaml     ### 查看mysecret详细信息
12 apiVersion: v1
13 data:
14   password: MWYyZDFlMmU2N2Rm
15   username: YWRtaW4=
16 kind: Secret
17 metadata:
18   annotations:
19     kubectl.kubernetes.io/last-applied-configuration: |
20       {"apiVersion":"v1","data":{"password":"MWYyZDFlMmU2N2Rm","username":"YWRtaW4="},"kind":"Secret","metadata":{"annotations":{},"name":"mysecret","namespace":"default"},"type":"Opaque"}
21   creationTimestamp: "2020-06-08T14:08:59Z"
22   name: mysecret
23   namespace: default
24   resourceVersion: "987419"
25   selfLink: /api/v1/namespaces/default/secrets/mysecret
26   uid: 27b58929-71c4-495b-99a5-0d411910a529
27 type: Opaque
28 [root@k8s-master secret]# 
29 [root@k8s-master secret]# kubectl describe secret mysecret     ### 查看描述信息
30 Name:         mysecret
31 Namespace:    default
32 Labels:       <none>
33 Annotations:  
34 Type:         Opaque
35 
36 Data
37 ====
38 password:  12 bytes
39 username:  5 bytes

将Secret挂载到Volume中

yaml文件

 1 [root@k8s-master secret]# pwd
 2 /root/k8s_practice/secret
 3 [root@k8s-master secret]# cat pod_secret_volume.yaml 
 4 apiVersion: v1
 5 kind: Pod
 6 metadata:
 7   name: pod-secret-volume
 8 spec:
 9   containers:
10   - name: myapp
11     image: registry.cn-beijing.aliyuncs.com/google_registry/myapp:v1
12     volumeMounts:
13     - name: secret-volume
14       mountPath: /etc/secret
15       readOnly: true
16   volumes:
17   - name: secret-volume
18     secret:
19       secretName: mysecret

启动pod并查看状态

1 [root@k8s-master secret]# kubectl apply -f pod_secret_volume.yaml 
2 pod/pod-secret-volume created
3 [root@k8s-master secret]# 
4 [root@k8s-master secret]# kubectl get pod -o wide
5 NAME                READY   STATUS    RESTARTS   AGE   IP             NODE         NOMINATED NODE   READINESS GATES
6 pod-secret-volume   1/1     Running   0          16s   10.244.2.159   k8s-node02   <none>           <none>

查看secret信息

1 [root@k8s-master secret]# kubectl exec -it pod-secret-volume -- /bin/sh
2 / # ls /etc/secret
3 password  username
4 / # 
5 / # cat /etc/secret/username
6 admin/ # 
7 / # 
8 / # cat /etc/secret/password
9 1f2d1e2e67df/ #

由上可见，在pod中的secret信息实际已经被解密。

将Secret导入到环境变量中

yaml文件

 1 [root@k8s-master secret]# pwd
 2 /root/k8s_practice/secret
 3 [root@k8s-master secret]# cat pod_secret_env.yaml 
 4 apiVersion: v1
 5 kind: Pod
 6 metadata:
 7   name: pod-secret-env
 8 spec:
 9   containers:
10   - name: myapp
11     image: registry.cn-beijing.aliyuncs.com/google_registry/myapp:v1
12     env:
13     - name: SECRET_USERNAME
14       valueFrom:
15         secretKeyRef:
16           name: mysecret
17           key: username
18     - name: SECRET_PASSWORD
19       valueFrom:
20         secretKeyRef:
21           name: mysecret
22           key: password
23   restartPolicy: Never

启动pod并查看状态

1 [root@k8s-master secret]# kubectl apply -f pod_secret_env.yaml 
2 pod/pod-secret-env created
3 [root@k8s-master secret]# 
4 [root@k8s-master secret]# kubectl get pod -o wide
5 NAME             READY   STATUS    RESTARTS   AGE   IP             NODE         NOMINATED NODE   READINESS GATES
6 pod-secret-env   1/1     Running   0          6s    10.244.2.160   k8s-node02   <none>           <none>

查看secret信息

 1 [root@k8s-master secret]# kubectl exec -it pod-secret-env -- /bin/sh
 2 / # env
 3 ………………
 4 HOME=/root
 5 SECRET_PASSWORD=1f2d1e2e67df    ### secret信息
 6 MYAPP_SVC_PORT_80_TCP=tcp://10.98.57.156:80
 7 TERM=xterm
 8 NGINX_VERSION=1.12.2
 9 KUBERNETES_PORT_443_TCP_ADDR=10.96.0.1
10 PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
11 KUBERNETES_PORT_443_TCP_PORT=443
12 KUBERNETES_PORT_443_TCP_PROTO=tcp
13 MYAPP_SVC_SERVICE_HOST=10.98.57.156
14 SECRET_USERNAME=admin    ### secret信息
15 KUBERNETES_PORT_443_TCP=tcp://10.96.0.1:443
16 ………………

由上可见，在pod中的secret信息实际已经被解密。

docker-registry Secret

harbor镜像仓库

首先使用harbor搭建镜像仓库，搭建部署过程参考：「Harbor企业级私有Docker镜像仓库部署」

 1 [root@k8s-master harbor]# pwd
 2 /root/App/harbor
 3 [root@k8s-master harbor]# vim harbor.yml 
 4 # Configuration file of Harbor
 5 hostname: 172.16.1.110
 6 
 7 # http related config
 8 http:
 9   # port for http, default is 80. If https enabled, this port will redirect to https port
10   port: 5000
11 
12 # https related config
13 https:
14   # https port for harbor, default is 443
15   port: 443
16   # The path of cert and key files for nginx
17   certificate: /etc/harbor/cert/httpd.crt
18   private_key: /etc/harbor/cert/httpd.key
19 harbor_admin_password: Harbor12345

集群所有机器都要操作

 1 [root@k8s-master ~]# vim /etc/docker/daemon.json
 2 {
 3   "exec-opts": ["native.cgroupdriver=systemd"],
 4   "log-driver": "json-file",
 5   "log-opts": {
 6     "max-size": "100m"
 7   },
 8   "insecure-registries": ["172.16.1.110:5000"]
 9 }
10 [root@k8s-master ~]# 
11 [root@k8s-master ~]# systemctl restart docker   # 重启docker服务

 添加了 “insecure-registries”: [“172.16.1.110:5000”] 这行，其中172.16.1.110为内网IP地址。该文件必须符合 json 规范，否则 Docker 将不能启动。

如果在Harbor所在的机器重启了docker服务，记得要重新启动Harbor。

1 docker pull registry.cn-beijing.aliyuncs.com/google_registry/myapp:v1
2 docker tag registry.cn-beijing.aliyuncs.com/google_registry/myapp:v1 172.16.1.110:5000/k8s-secret/myapp:v1
3 # 登录
4 docker login 172.16.1.110:5000 -u admin -p Harbor12345
5 # 上传
6 docker push 172.16.1.110:5000/k8s-secret/myapp:v1

之后在操作机上退出harbor登录，便于后面演示

1 ### 退出harbor登录
2 [root@k8s-node02 ~]# docker logout 172.16.1.110:5000  
3 Removing login credentials for 172.16.1.110:5000
4 ### 拉取失败，需要先登录。表明完成准备工作
5 [root@k8s-master secret]# docker pull 172.16.1.110:5000/k8s-secret/myapp:v1
6 Error response from daemon: pull access denied for 172.16.1.110:5000/k8s-secret/myapp, repository does not exist or may require 'docker login': denied: requested access to the resource is denied

pod直接下载镜像

在yaml文件中指定image后，直接启动pod

 1 [root@k8s-master secret]# pwd
 2 /root/k8s_practice/secret
 3 [root@k8s-master secret]# cat pod_secret_registry.yaml 
 4 apiVersion: v1
 5 kind: Pod
 6 metadata:
 7   name: pod-secret-registry
 8 spec:
 9   containers:
10   - name: myapp
11     image: 172.16.1.110:5000/k8s-secret/myapp:v1

启动pod并查看状态

 1 [root@k8s-master secret]# kubectl apply -f pod_secret_registry.yaml 
 2 pod/pod-secret-registry created
 3 [root@k8s-master secret]# 
 4 [root@k8s-master secret]# kubectl get pod -o wide     ### 可见镜像下载失败
 5 NAME                  READY   STATUS             RESTARTS   AGE   IP             NODE         NOMINATED NODE   READINESS GATES
 6 pod-secret-registry   0/1     ImagePullBackOff   0          7s    10.244.2.161   k8s-node02   <none>           <none>
 7 [root@k8s-master secret]# 
 8 [root@k8s-master secret]# kubectl describe pod pod-secret-registry     ### 查看pod详情
 9 Name:         pod-secret-registry
10 Namespace:    default
11 Priority:     0
12 Node:         k8s-node02/172.16.1.112
13 Start Time:   Mon, 08 Jun 2020 23:59:07 +0800
14 Labels:       <none>
15 Annotations:  kubectl.kubernetes.io/last-applied-configuration:
16                 {"apiVersion":"v1","kind":"Pod","metadata":{"annotations":{},"name":"pod-secret-registry","namespace":"default"},"spec":{"containers":[{"i...
17 Status:       Pending
18 IP:           10.244.2.161
19 IPs:
20   IP:  10.244.2.161
21 Containers:
22   myapp:
23     Container ID:   
24     Image:          172.16.1.110:5000/k8s-secret/myapp:v1
25     Image ID:       
26 ………………
27 Events:
28   Type     Reason     Age                From                 Message
29   ----     ------     ----               ----                 -------
30   Normal   Scheduled  23s                default-scheduler    Successfully assigned default/pod-secret-registry to k8s-node02
31   Normal   BackOff    19s (x2 over 20s)  kubelet, k8s-node02  Back-off pulling image "172.16.1.110:5000/k8s-secret/myapp:v1"
32   Warning  Failed     19s (x2 over 20s)  kubelet, k8s-node02  Error: ImagePullBackOff
33   Normal   Pulling    9s (x2 over 21s)   kubelet, k8s-node02  Pulling image "172.16.1.110:5000/k8s-secret/myapp:v1"
34   Warning  Failed     9s (x2 over 21s)   kubelet, k8s-node02  Failed to pull image "172.16.1.110:5000/k8s-secret/myapp:v1": rpc error: code = Unknown desc = Error response from daemon: pull access denied for 172.16.1.110:5000/k8s-secret/myapp, repository does not exist or may require 'docker login': denied: requested access to the resource is denied
35   Warning  Failed     9s (x2 over 21s)   kubelet, k8s-node02  Error: ErrImagePull
36 [root@k8s-master secret]# 
37 [root@k8s-master secret]# kubectl delete -f pod_secret_registry.yaml

可见拉取私有镜像失败。

pod通过Secret下载镜像

通过命令行创建Secret，并查看其描述信息

 1 [root@k8s-master secret]# kubectl create secret docker-registry myregistrysecret --docker-server='172.16.1.110:5000' --docker-username='admin' --docker-password='Harbor12345' 
 2 secret/myregistrysecret created
 3 [root@k8s-master secret]#
 4 [root@k8s-master secret]# kubectl get secret 
 5 NAME                  TYPE                                  DATA   AGE
 6 basic-auth            Opaque                                1      2d14h
 7 default-token-v48g4   kubernetes.io/service-account-token   3      27d
 8 myregistrysecret      kubernetes.io/dockerconfigjson        1      8s    # 刚刚创建的
 9 mysecret              Opaque                                2      118m
10 tls-secret            kubernetes.io/tls                     2      3d4h
11 [root@k8s-master secret]# 
12 [root@k8s-master secret]# kubectl get secret myregistrysecret -o yaml     ### 查看详细信息
13 apiVersion: v1
14 data:
15   .dockerconfigjson: eyJhdXRocyI6eyIxMC4wLjAuMTEwOjUwMDAiOnsidXNlcm5hbWUiOiJhZG1pbiIsInBhc3N3b3JkIjoiSGFyYm9yMTIzNDUiLCJhdXRoIjoiWVdSdGFXNDZTR0Z5WW05eU1USXpORFU9In19fQ==
16 kind: Secret
17 metadata:
18   creationTimestamp: "2020-06-08T16:07:32Z"
19   name: myregistrysecret
20   namespace: default
21   resourceVersion: "1004582"
22   selfLink: /api/v1/namespaces/default/secrets/myregistrysecret
23   uid: b95f4386-64bc-4ba3-b43a-08afb1c1eb9d
24 type: kubernetes.io/dockerconfigjson
25 [root@k8s-master secret]# 
26 [root@k8s-master secret]# kubectl describe secret myregistrysecret     ### 查看描述信息
27 Name:         myregistrysecret
28 Namespace:    default
29 Labels:       <none>
30 Annotations:  <none>
31 
32 Type:  kubernetes.io/dockerconfigjson
33 
34 Data
35 ====
36 .dockerconfigjson:  109 bytes

修改之前的yaml文件

 1 [root@k8s-master secret]# cat pod_secret_registry.yaml 
 2 apiVersion: v1
 3 kind: Pod
 4 metadata:
 5   name: pod-secret-registry
 6 spec:
 7   containers:
 8   - name: myapp
 9     image: 172.16.1.110:5000/k8s-secret/myapp:v1
10   imagePullSecrets:
11   - name: myregistrysecret

启动pod并查看状态

 1 [root@k8s-master secret]# kubectl apply -f pod_secret_registry.yaml 
 2 pod/pod-secret-registry created
 3 [root@k8s-master secret]# 
 4 [root@k8s-master secret]# kubectl get pod -o wide
 5 NAME                  READY   STATUS    RESTARTS   AGE   IP             NODE         NOMINATED NODE   READINESS GATES
 6 pod-secret-registry   1/1     Running   0          8s    10.244.2.162   k8s-node02   <none>           <none>
 7 [root@k8s-master secret]# 
 8 [root@k8s-master secret]# kubectl describe pod pod-secret-registry
 9 Name:         pod-secret-registry
10 Namespace:    default
11 Priority:     0
12 Node:         k8s-node02/172.16.1.112
13 Start Time:   Tue, 09 Jun 2020 00:22:40 +0800
14 Labels:       <none>
15 Annotations:  kubectl.kubernetes.io/last-applied-configuration:
16                 {"apiVersion":"v1","kind":"Pod","metadata":{"annotations":{},"name":"pod-secret-registry","namespace":"default"},"spec":{"containers":[{"i...
17 Status:       Running
18 IP:           10.244.2.162
19 IPs:
20   IP:  10.244.2.162
21 Containers:
22   myapp:
23     Container ID:   docker://ef4d42f1f1616a44c2a6c0a5a71333b27f46dfe76eb392962813a28d69150c00
24     Image:          172.16.1.110:5000/k8s-secret/myapp:v1
25     Image ID:       docker-pullable://172.16.1.110:5000/k8s-secret/myapp@sha256:9eeca44ba2d410e54fccc54cbe9c021802aa8b9836a0bcf3d3229354e4c8870e
26     Port:           <none>
27     Host Port:      <none>
28     State:          Running
29       Started:      Tue, 09 Jun 2020 00:22:41 +0800
30     Ready:          True
31     Restart Count:  0
32     Environment:    <none>
33     Mounts:
34       /var/run/secrets/kubernetes.io/serviceaccount from default-token-v48g4 (ro)
35 Conditions:
36   Type              Status
37   Initialized       True 
38   Ready             True 
39   ContainersReady   True 
40   PodScheduled      True 
41 Volumes:
42   default-token-v48g4:
43     Type:        Secret (a volume populated by a Secret)
44     SecretName:  default-token-v48g4
45     Optional:    false
46 QoS Class:       BestEffort
47 Node-Selectors:  <none>
48 Tolerations:     node.kubernetes.io/not-ready:NoExecute for 300s
49                  node.kubernetes.io/unreachable:NoExecute for 300s
50 Events:
51   Type    Reason     Age   From                 Message
52   ----    ------     ----  ----                 -------
53   Normal  Scheduled  22s   default-scheduler    Successfully assigned default/pod-secret-registry to k8s-node02
54   Normal  Pulling    22s   kubelet, k8s-node02  Pulling image "172.16.1.110:5000/k8s-secret/myapp:v1"
55   Normal  Pulled     22s   kubelet, k8s-node02  Successfully pulled image "172.16.1.110:5000/k8s-secret/myapp:v1"
56   Normal  Created    22s   kubelet, k8s-node02  Created container myapp
57   Normal  Started    21s   kubelet, k8s-node02  Started container myapp

由上可见，通过secret认证后pod拉取私有镜像是可以的。