• kubernetes之configmap,深度解析mountPath,subPath,key,path的关系和作用


    参考:https://www.cnblogs.com/breezey/p/6582082.html

     

    我们知道,在几乎所有的应用开发中,都会涉及到配置文件的变更,比如说在web的程序中,需要连接数据库,缓存甚至是队列等等。而我们的一个应用程序从写第一行代码开始,要经历开发环境、测试环境、预发布环境只到最终的线上环境。而每一个环境都要定义其独立的各种配置。如果我们不能很好的管理这些配置文件,你的运维工作将顿时变的无比的繁琐。为此业内的一些大公司专门开发了自己的一套配置管理中心,如360的Qcon,百度的disconf等。kubernetes也提供了自己的一套方案,即ConfigMap。kubernetes通过ConfigMap来实现对容器中应用的配置管理。

    1.创建configmap

    1.1 通过yaml创建

    我们先来看第一种,在yaml文件中,配置文件以key-value键值对的形式保存,当然也可以直接放一个完整的配置文件,在下面的示例中,cache_hst、cache_port、cache_prefix即是key-value键值对,而app.properties和my.cnf都是配置文件:

    [root@k8s-master k8s-objs]# pwd
    /root/k8s-objs
    [root@k8s-master k8s-objs]# cat configmap-test1.yaml 
    apiVersion: v1
    kind: ConfigMap
    metadata:
      name: test-cfg
      namespace: default
    data:
      cache_host: mysql-k8s
      cache_port: "33006"
      cache_prefix: k8s
      my.cnf: |
        [mysqld]
        log-bin = mysql-bin
      app.properties: |
        property.1 = value-1
        property.2 = value-2
        property.3 = value-3
    [root@k8s-master k8s-objs]# 
    [root@k8s-master k8s-objs]# kubectl create -f configmap-test1.yaml 
    configmap/test-cfg created
    
    
    [root@k8s-master k8s-objs]# kubectl get configmaps
    NAME       DATA   AGE
    test-cfg   5      85s
    [root@k8s-master k8s-objs]# kubectl describe pod test-cfg 
    Error from server (NotFound): pods "test-cfg" not found
    [root@k8s-master k8s-objs]# kubectl describe configmap test-cfg    
    Name:         test-cfg
    Namespace:    default
    Labels:       <none>
    Annotations:  <none>
    
    Data
    ====
    app.properties:
    ----
    property.1 = value-1
    property.2 = value-2
    property.3 = value-3
    
    cache_host:
    ----
    mysql-k8s
    cache_port:
    ----
    33006
    cache_prefix:
    ----
    k8s
    my.cnf:
    ----
    [mysqld]
    log-bin = mysql-bin
    
    Events:  <none>
    [root@k8s-master k8s-objs]# 

    1.2 通过命令创建configmap

    kubectl create configmap test-config3 --from-literal=db.host=10.5.10.116 --from-literal=db.port='3306'

    ##直接将文件创建为configmap

    ##kubectl create configmap test-config --from-file=./configs ##将该目录下的所有配置文件创建为configmap
    ##kubectl create configmap test-config2 --from-file=./configs/db.conf --from-file=./configs/cache.conf

     

    [root@k8s-master k8s-objs]# kubectl create configmap test-config3 --from-literal=db.host=10.5.10.116 --from-literal=db.port='3306'
    configmap/test-config3 created
    [root@k8s-master k8s-objs]# kubectl get configmaps              
    NAME           DATA   AGE
    test-cfg       5      6m1s
    test-config3   2      9s
    [root@k8s-master k8s-objs]# kubectl describe configmap test-cfg3
    Error from server (NotFound): configmaps "test-cfg3" not found
    [root@k8s-master k8s-objs]# kubectl describe configmap test-config3
    Name:         test-config3
    Namespace:    default
    Labels:       <none>
    Annotations:  <none>
    
    Data
    ====
    db.host:
    ----
    10.5.10.116
    db.port:
    ----
    3306
    Events:  <none>
    [root@k8s-master k8s-objs]# 

     查看属性

    [root@k8s-master k8s-objs]# kubectl get configmaps -o yaml         
    apiVersion: v1
    items:
    - apiVersion: v1
      data:
        app.properties: |
          property.1 = value-1
          property.2 = value-2
          property.3 = value-3
        cache_host: mysql-k8s
        cache_port: "33006"
        cache_prefix: k8s
        my.cnf: |
          [mysqld]
          log-bin = mysql-bin
      kind: ConfigMap
      metadata:
        creationTimestamp: "2019-04-11T08:25:13Z"
        name: test-cfg
        namespace: default
        resourceVersion: "976815"
        selfLink: /api/v1/namespaces/default/configmaps/test-cfg
        uid: 544cc424-5c33-11e9-a5c3-000c291ae345

    ###第二个configmap
    - apiVersion: v1 data: db.host: 10.5.10.116 db.port: "3306" kind: ConfigMap metadata: creationTimestamp: "2019-04-11T08:31:05Z" name: test-config3 namespace: default resourceVersion: "977288" selfLink: /api/v1/namespaces/default/configmaps/test-config3 uid: 261ab5e2-5c34-11e9-a5c3-000c291ae345 kind: List metadata: resourceVersion: "" selfLink: ""

     2 使用configmap

    2.1 作为环境变量

    [root@k8s-master k8s-objs]# cat pod-configmap-testenv.yaml 
    apiVersion: v1
    kind: Pod
    metadata:
      labels:
        purpose: test-configmap
      name: testenv
    spec:
      containers:
        - name: test-configmap
          image: tomcat:8
          imagePullPolicy: IfNotPresent
          #command: [ "/bin/sh", "-c", "echo $(MY_CACHE_HOST)" ]
          env:
            - name: MY_CACHE_HOST
              valueFrom:
                configMapKeyRef:
                  name: test-cfg
                  key: cache_host
    [root@k8s-master k8s-objs]# 
    [root@k8s-master k8s-objs]# kubectl create -f pod-configmap-testenv.yaml 
    pod/testenv created
    root@k8s-master k8s-objs]# kubectl get pod
    NAME                     READY   STATUS    RESTARTS   AGE
    hello-5cd4456b66-gstq6   1/1     Running   1          8d
    hello-5cd4456b66-sb5px   1/1     Running   1          8d
    testenv                  1/1     Running   0          7s


    #查看containerid
    [root@k8s-master k8s-objs]# kubectl describe pod testenv
    Name:               testenv
    Namespace:          default
    Priority:           0
    PriorityClassName:  <none>
    Node:               k8s-node1/192.168.111.131
    Start Time:         Fri, 12 Apr 2019 08:28:27 +0800
    Labels:             purpose=test-configmap
    Annotations:        <none>
    Status:             Running
    IP:                 10.244.1.69
    Containers:
      test-configmap:
        Container ID:   docker://7c76ff1602561c498a537ea0bcd3bb0a244a7ef9ec3cdc34b6ba03577d889a93
        Image:          tomcat:8
        Image ID:       docker-pullable://tomcat@sha256:3e3d18321127bb9114f4226f95802d3899aeec4c36df84d0359e5da300e9bc72
        Port:           <none>
        Host Port:      <none>
        State:          Running
          Started:      Fri, 12 Apr 2019 08:28:33 +0800
        Ready:          True
        Restart Count:  0
        Environment:
          MY_CACHE_HOST:  <set to the key 'cache_host' of config map 'test-cfg'>  Optional: false
        Mounts:
          /var/run/secrets/kubernetes.io/serviceaccount from default-token-92rjn (ro)
    Conditions:
      Type              Status
      Initialized       True
      Ready             True
      ContainersReady   True
      PodScheduled      True
    Volumes:
      default-token-92rjn:
        Type:        Secret (a volume populated by a Secret)
        SecretName:  default-token-92rjn
        Optional:    false
    QoS Class:       BestEffort
    Node-Selectors:  <none>
    Tolerations:     node.kubernetes.io/not-ready:NoExecute for 300s
                     node.kubernetes.io/unreachable:NoExecute for 300s
    Events:
      Type    Reason     Age    From                Message
      ----    ------     ----   ----                -------
      Normal  Scheduled  2m49s  default-scheduler   Successfully assigned default/testenv to k8s-node1
      Normal  Pulled     2m44s  kubelet, k8s-node1  Container image "tomcat:8" already present on machine
      Normal  Created    2m44s  kubelet, k8s-node1  Created container test-configmap
      Normal  Started    2m43s  kubelet, k8s-node1  Started container test-configmap
    [root@k8s-master k8s-objs]#


    进入kubernetes中的pod的容器中,

    kubectl exec -it testenv -n default -- /bin/bash #退出exit

    [root@k8s-master k8s-objs]# kubectl exec -it testenv -n default -- /bin/bash ##下面标红表示新的pod主机名,即已成功进入pod
    root@testenv:/usr/local/tomcat# 
    root@testenv:/usr/local/tomcat# echo $MY_CACHE_HOST #查看环境变量是否生效
    mysql-k8s
    root@testenv:/usr/local/tomcat# exit

     2.2 挂载文件数据卷

    2.2.1使用volume将ConfigMap作为文件或目录直接挂载,其中每一个key-value键值对都会生成一个文件,key为文件名,value为内容

    查看configmap

    [root@k8s-master k8s-objs]# kubectl get configmap
    NAME           DATA   AGE
    test-cfg       5      16h
    test-config3   2      16h
    [root@k8s-master k8s-objs]# kubectl get configmap test-cfg -o yaml       
    apiVersion: v1
    data:
      app.properties: |
        property.1 = value-1
        property.2 = value-2
        property.3 = value-3
      cache_host: mysql-k8s
      cache_port: "33006"
      cache_prefix: k8s
      my.cnf: |
        [mysqld]
        log-bin = mysql-bin
    kind: ConfigMap
    metadata:
      creationTimestamp: "2019-04-11T08:25:13Z"
      name: test-cfg
      namespace: default
      resourceVersion: "976815"
      selfLink: /api/v1/namespaces/default/configmaps/test-cfg
      uid: 544cc424-5c33-11e9-a5c3-000c291ae345
    [root@k8s-master k8s-objs]# 

    创建pod,并挂载volume

    [root@k8s-master k8s-objs]# cat pod-configmap-testvolume.yaml
    apiVersion: v1
    kind: Pod
    metadata:
      labels:
        purpose: test-configmap-volume
      name: testvolume
    spec:
      containers:
        - name: test-configmap-volume
          image: tomcat:8
          imagePullPolicy: IfNotPresent
          #command: [ "/bin/sh", "-c", "echo $(MY_CACHE_HOST)" ]
          volumeMounts:
            - name: config-volume
              mountPath: /etc/config
      volumes:
        - name: config-volume
          configMap:
             name: test-cfg
    
    [root@k8s-master k8s-objs]# 
    [root@k8s-master k8s-objs]# kubectl create -f pod-configmap-testvolume.yaml
    pod/testvolume created
    [root@k8s-master k8s-objs]# kubectl get pod
    NAME                     READY   STATUS    RESTARTS   AGE
    hello-5cd4456b66-gstq6   1/1     Running   1          8d
    hello-5cd4456b66-sb5px   1/1     Running   1          8d
    testvolume               1/1     Running   0          113s
    [root@k8s-master k8s-objs]# kubectl describe pod testvolume
    Name:               testvolume
    Namespace:          default
    Priority:           0
    PriorityClassName:  <none>
    Node:               k8s-node1/192.168.111.131
    Start Time:         Fri, 12 Apr 2019 08:59:31 +0800
    Labels:             purpose=test-configmap-volume
    Annotations:        <none>
    Status:             Running
    IP:                 10.244.1.70
    Containers:
      test-configmap-volume:
        Container ID:   docker://16de1a9dec62564d6e7e50a3167581e9be8151c388707e8f48f4f5152a0ed83a
        Image:          tomcat:8
        Image ID:       docker-pullable://tomcat@sha256:3e3d18321127bb9114f4226f95802d3899aeec4c36df84d0359e5da300e9bc72
        Port:           <none>
        Host Port:      <none>
        State:          Running
          Started:      Fri, 12 Apr 2019 08:59:34 +0800
        Ready:          True
        Restart Count:  0
        Environment:    <none>
        Mounts:
          /etc/config from config-volume (rw)
          /var/run/secrets/kubernetes.io/serviceaccount from default-token-92rjn (ro)
    Conditions:
      Type              Status
      Initialized       True 
      Ready             True 
      ContainersReady   True 
      PodScheduled      True 
    Volumes:
      config-volume:
        Type:      ConfigMap (a volume populated by a ConfigMap)
        Name:      test-cfg
        Optional:  false
      default-token-92rjn:
        Type:        Secret (a volume populated by a Secret)
        SecretName:  default-token-92rjn
        Optional:    false
    QoS Class:       BestEffort
    Node-Selectors:  <none>
    Tolerations:     node.kubernetes.io/not-ready:NoExecute for 300s
                     node.kubernetes.io/unreachable:NoExecute for 300s
    Events:
      Type    Reason     Age    From                Message
      ----    ------     ----   ----                -------
      Normal  Scheduled  2m45s  default-scheduler   Successfully assigned default/testvolume to k8s-node1
      Normal  Pulled     2m42s  kubelet, k8s-node1  Container image "tomcat:8" already present on machine
      Normal  Created    2m42s  kubelet, k8s-node1  Created container test-configmap-volume
      Normal  Started    2m42s  kubelet, k8s-node1  Started container test-configmap-volume
    [root@k8s-master k8s-objs]# 


    进入kubernetes的pod,

    [root@k8s-master k8s-objs]# kubectl get pod
    NAME                     READY   STATUS    RESTARTS   AGE
    hello-5cd4456b66-gstq6   1/1     Running   1          8d
    hello-5cd4456b66-sb5px   1/1     Running   1          8d
    testvolume               1/1     Running   0          3m56s
    [root@k8s-master k8s-objs]# kubectl exec -it testsvolume /bin/bash
    Error from server (NotFound): pods "testsvolume" not found
    [root@k8s-master k8s-objs]# kubectl exec -it testvolume /bin/bash 
    root@testvolume:/usr/local/tomcat# cd /etc/config
    root@testvolume:/etc/config# ls
    app.properties  cache_host  cache_port  cache_prefix  my.cnf
    root@testvolume:/etc/config# ll
    bash: ll: command not found
    root@testvolume:/etc/config# ls -l ##对照发现,使用volume将ConfigMap作为文件或目录直接挂载,其中每一个key-value键值对都会生成一个文件,key为文件名,value为内容
    total 0
    lrwxrwxrwx 1 root root 21 Apr 12 00:59 app.properties -> ..data/app.properties
    lrwxrwxrwx 1 root root 17 Apr 12 00:59 cache_host -> ..data/cache_host
    lrwxrwxrwx 1 root root 17 Apr 12 00:59 cache_port -> ..data/cache_port
    lrwxrwxrwx 1 root root 19 Apr 12 00:59 cache_prefix -> ..data/cache_prefix
    lrwxrwxrwx 1 root root 13 Apr 12 00:59 my.cnf -> ..data/my.cnf
    root@testvolume:/etc/config# cat app.properties
    property.1 = value-1
    property.2 = value-2
    property.3 = value-3
    root@testvolume:/etc/config# cat cache_host
    mysql-k8sroot@testvolume:/etc/config# cat cache_port
    33006root@testvolume:/etc/config# cat cache_prefix
    k8sroot@testvolume:/etc/config# cat my.cnf
    [mysqld]
    log-bin = mysql-bin
    root@testvolume:/usr/local/tomcat# echo $cache_host ##并没有自动生成环境变量
    
    root@testvolume:/usr/local/tomcat#
    root@testvolume:/etc/config# exit


    2.2.2 另一种方式,只挂载某个key,并支持相对路径,其中一个key生成的文件路径名和文件名相同

     

    [root@k8s-master k8s-objs]# cat pod-configmap-testvolume.yaml
    apiVersion: v1
    kind: Pod
    metadata:
      labels:
        purpose: test-configmap-volume
      name: testvolume
    spec:
      containers:
        - name: test-configmap-volume
          image: tomcat:8
          imagePullPolicy: IfNotPresent
          #command: [ "/bin/sh", "-c", "echo $(MY_CACHE_HOST)" ]
          volumeMounts:
            - name: config-volume
              mountPath: /etc/config
      volumes:
        - name: config-volume
          configMap:
             name: test-cfg
             items:
               - key: cache_host
                 path: path/to/special-key-cache #path中的最后一级“special-key-cache”为文件名
               - key: app.properties
                 path: app.properties
    [root@k8s-master k8s-objs]# kubectl create -f pod-configmap-testvolume.yaml
    pod/testvolume created
    [root@k8s-master k8s-objs]# kubectl get pod
    NAME                     READY   STATUS    RESTARTS   AGE
    hello-5cd4456b66-gstq6   1/1     Running   1          8d
    hello-5cd4456b66-sb5px   1/1     Running   1          8d
    testvolume               1/1     Running   0          12s
    [root@k8s-master k8s-objs]# kubectl describe pod testvolume   
    Name:               testvolume
    Namespace:          default
    Priority:           0
    PriorityClassName:  <none>
    Node:               k8s-node1/192.168.111.131
    Start Time:         Fri, 12 Apr 2019 09:19:49 +0800
    Labels:             purpose=test-configmap-volume
    Annotations:        <none>
    Status:             Running
    IP:                 10.244.1.71
    Containers:
      test-configmap-volume:
        Container ID:   docker://227d2ab39823087193f1830309c73af5408c85f634eb5c7fce9c668533766b76
        Image:          tomcat:8
        Image ID:       docker-pullable://tomcat@sha256:3e3d18321127bb9114f4226f95802d3899aeec4c36df84d0359e5da300e9bc72
        Port:           <none>
        Host Port:      <none>
        State:          Running
          Started:      Fri, 12 Apr 2019 09:19:53 +0800
        Ready:          True
        Restart Count:  0
        Environment:    <none>
        Mounts:
          /etc/config from config-volume (rw)
          /var/run/secrets/kubernetes.io/serviceaccount from default-token-92rjn (ro)
    Conditions:
      Type              Status
      Initialized       True 
      Ready             True 
      ContainersReady   True 
      PodScheduled      True 
    Volumes:
      config-volume:
        Type:      ConfigMap (a volume populated by a ConfigMap)
        Name:      test-cfg
        Optional:  false
      default-token-92rjn:
        Type:        Secret (a volume populated by a Secret)
        SecretName:  default-token-92rjn
        Optional:    false
    QoS Class:       BestEffort
    Node-Selectors:  <none>
    Tolerations:     node.kubernetes.io/not-ready:NoExecute for 300s
                     node.kubernetes.io/unreachable:NoExecute for 300s
    Events:
      Type    Reason     Age    From                Message
      ----    ------     ----   ----                -------
      Normal  Scheduled  2m27s  default-scheduler   Successfully assigned default/testvolume to k8s-node1
      Normal  Pulled     2m24s  kubelet, k8s-node1  Container image "tomcat:8" already present on machine
      Normal  Created    2m23s  kubelet, k8s-node1  Created container test-configmap-volume
      Normal  Started    2m23s  kubelet, k8s-node1  Started container test-configmap-volume
    [root@k8s-master k8s-objs]# 

    进入pod

    [root@k8s-master k8s-objs]# kubectl get pod
    NAME                     READY   STATUS    RESTARTS   AGE
    hello-5cd4456b66-gstq6   1/1     Running   1          8d
    hello-5cd4456b66-sb5px   1/1     Running   1          8d
    testvolume               1/1     Running   0          3m24s
    [root@k8s-master k8s-objs]# kubectl exec -it testvolume /bin/bash
    root@testvolume:/usr/local/tomcat# cd /etc/config
    root@testvolume:/etc/config# ls -l #在目录/etc/config下生成一个文件(/etc/config/app.properties)和一个带path目录的文件(/etc/config/path/to/special-key-cache)
    total 0
    lrwxrwxrwx 1 root root 21 Apr 12 01:19 app.properties -> ..data/app.properties
    lrwxrwxrwx 1 root root 11 Apr 12 01:19 path -> ..data/path
    root@testvolume:/etc/config# ls app.properties
    app.properties
    root@testvolume:/etc/config# cat app.properties/app.properties
    cat: app.properties/app.properties: Not a directory
    root@testvolume:/etc/config# cd app.properties
    bash: cd: app.properties: Not a directory
    root@testvolume:/etc/config# cat app.properties ##说明key:app.properties的path项用文件名相当于没有起任何作用
    property.1 = value-1
    property.2 = value-2
    property.3 = value-3
    root@testvolume:/etc/config# pwd
    /etc/config
    root@testvolume:/etc/config# cd path/to/special-key-cache 
    bash: cd: path/to/special-key-cache: Not a directory
    root@testvolume:/etc/config# cd path
    root@testvolume:/etc/config/path# cd to
    root@testvolume:/etc/config/path/to# cd special-key-cache
    bash: cd: special-key-cache: Not a directory
    root@testvolume:/etc/config/path/to# pwd
    /etc/config/path/to
    root@testvolume:/etc/config/path/to# ls
    special-key-cache
    root@testvolume:/etc/config/path/to# cat special-key-cache 
    mysql-k8sroot@testvolume:/etc/config/path/to# exit

    configmap在pod容器中成功生成了文件

    3 深度解析mountPath,subPath,key,path的关系和作用

    结论:

    kubernetes key (pod.spec.volums[0].configMap.items[0].key)用于指定configMap中的哪些条目可用于挂载,如2.2.2

    kubernetes path (pod.spec.volums[0].configMap.items[0].path)用于将key重命名,如案例3.3

    kubernetes suPath (pod.spec.containers[0].volumeMounts.subPath)决定容器中有无挂载(按名字从key,有path时以path为主,中比对是否存在要的条目)。

    kubernetes mountPath (pod.spec.containers[0].volumeMounts.mountPath)决定容器中挂载的结果文件名。没有subPath项时如案例2.2.1,此项仅指定路径。有subPath时且subPath筛选结果为true时如案例3.1,此项指定路径和文件名,此时文件名可随意指定如案例3.4和3.5;有subPath但subPath筛选结果为false时如案例3.2,此项指定路径(最后一级目录名为文件名)

    3.1 mountPath结合subPath(也可解决多个configmap挂载同一目录,导致覆盖)作用

    有subPath时且subPath推荐筛选结果为true,mountPath指定到文件名

    注:subPath只是将volume.items.key中多个key进行筛选,只挂载需要的文件,相当于2.2.2中app.properties保留,其它key不挂载

    [root@k8s-master k8s-objs]# cat pod-configmap-testvolume.yaml
    apiVersion: v1
    kind: Pod
    metadata:
      labels:
        purpose: test-configmap-volume
      name: testvolume
    spec:
      containers:
        - name: test-configmap-volume
          image: tomcat:8
          imagePullPolicy: IfNotPresent
          #command: [ "/bin/sh", "-c", "echo $(MY_CACHE_HOST)" ]
          volumeMounts:
            - name: config-volume
              mountPath: /etc/config/app.properties #此处配合suPath使用时,app.properties为文件名,即pod容器中只生成了/etc/config目录,目录之下 为文件,只有一个名为app.properties的文件(subPath筛选只挂载app.properties文件)
              subPath: app.properties
      volumes:
        - name: config-volume
          configMap:
             name: test-cfg
             items:
               - key: cache_host
                 path: path/to/special-key-cache
               - key: app.properties
                 path: app.properties
    [root@k8s-master k8s-objs]# kubectl create -f pod-configmap-testvolume.yaml
    pod/testvolume created
    [root@k8s-master k8s-objs]# kubectl get pod
    NAME                     READY   STATUS    RESTARTS   AGE
    hello-5cd4456b66-gstq6   1/1     Running   1          8d
    hello-5cd4456b66-sb5px   1/1     Running   1          8d
    testvolume               1/1     Running   0          17s
    [root@k8s-master k8s-objs]# 
    [root@k8s-master k8s-objs]# kubectl describe pod testvolume
    Name:               testvolume
    Namespace:          default
    Priority:           0
    PriorityClassName:  <none>
    Node:               k8s-node1/192.168.111.131
    Start Time:         Fri, 12 Apr 2019 09:59:24 +0800
    Labels:             purpose=test-configmap-volume
    Annotations:        <none>
    Status:             Running
    IP:                 10.244.1.72
    Containers:
      test-configmap-volume:
        Container ID:   docker://ef581eaaf8bd895bce8d4e77f66b8c704b557dee186bf72e00e1aa3dbb7390f4
        Image:          tomcat:8
        Image ID:       docker-pullable://tomcat@sha256:3e3d18321127bb9114f4226f95802d3899aeec4c36df84d0359e5da300e9bc72
        Port:           <none>
        Host Port:      <none>
        State:          Running
          Started:      Fri, 12 Apr 2019 09:59:27 +0800
        Ready:          True
        Restart Count:  0
        Environment:    <none>
        Mounts:
          /etc/config/app.properties from config-volume (rw,path="app.properties")
          /var/run/secrets/kubernetes.io/serviceaccount from default-token-92rjn (ro)
    Conditions:
      Type              Status
      Initialized       True 
      Ready             True 
      ContainersReady   True 
      PodScheduled      True 
    Volumes:
      config-volume:
        Type:      ConfigMap (a volume populated by a ConfigMap)
        Name:      test-cfg
        Optional:  false
      default-token-92rjn:
        Type:        Secret (a volume populated by a Secret)
        SecretName:  default-token-92rjn
        Optional:    false
    QoS Class:       BestEffort
    Node-Selectors:  <none>
    Tolerations:     node.kubernetes.io/not-ready:NoExecute for 300s
                     node.kubernetes.io/unreachable:NoExecute for 300s
    Events:
      Type    Reason     Age    From                Message
      ----    ------     ----   ----                -------
      Normal  Scheduled  2m13s  default-scheduler   Successfully assigned default/testvolume to k8s-node1
      Normal  Pulled     2m10s  kubelet, k8s-node1  Container image "tomcat:8" already present on machine
      Normal  Created    2m10s  kubelet, k8s-node1  Created container test-configmap-volume
      Normal  Started    2m10s  kubelet, k8s-node1  Started container test-configmap-volume
    [root@k8s-master k8s-objs]# 


    进入pod

    [root@k8s-master k8s-objs]# kubectl exec -it testvolume /bin/bash
    root@testvolume:/usr/local/tomcat# cd /etc/config
    root@testvolume:/etc/config# ls
    app.properties
    root@testvolume:/etc/config# ll
    bash: ll: command not found
    root@testvolume:/etc/config# ls
    app.properties
    root@testvolume:/etc/config# ls -l
    total 4
    -rw-r--r-- 1 root root 63 Apr 12 01:59 app.properties
    root@testvolume:/etc/config# cd app.properties 
    bash: cd: app.properties: Not a directory
    root@testvolume:/etc/config# cat app.properties 
    property.1 = value-1
    property.2 = value-2
    property.3 = value-3
    root@testvolume:/etc/config# 


    3.2有subPath但筛选结果为false, 

    容器中生成一个空目录/etc/config/app.properties,无文件

    解析。subPath筛选范围优先级为pod.spec.volums[0].configMap.items[0].path>pod.spec.volums[0].configMap.items[0].key>configMap.key,本例中为path,即在path指定的条目【“cache_host”,"app-properties "注意中间是横杠不是点】找是否有subPath项“app.properties”注意中间为点,查找结果为false,所以无文件挂载。容器将“/etc/config/app.properties”当成一个待创建的路径。

    [root@k8s-master k8s-objs]# vi pod-configmap-testvolume.yaml
    
    apiVersion: v1
    kind: Pod
    metadata:
      labels:
        purpose: test-configmap-volume
      name: testvolume
    spec:
      containers:
        - name: test-configmap-volume
          image: tomcat:8
          imagePullPolicy: IfNotPresent
          #command: [ "/bin/sh", "-c", "echo $(MY_CACHE_HOST)" ]
          volumeMounts:
            - name: config-volume
              mountPath: /etc/config/app.properties #此时此处app.properties为文件名
              subPath: app.properties
      volumes:
        - name: config-volume
          configMap:
             name: test-cfg
             items:
               - key: cache_host
                 path: path/to/special-key-cache
               - key: app.properties
                 path: app-properties #此处path相当于更改文件名mv app.properties app-properties 
    [root@k8s
    -master k8s-objs]# kubectl exec -it testvolume /bin/bash root@testvolume:/usr/local/tomcat# cd /etc/config root@testvolume:/etc/config# ls app.properties root@testvolume:/etc/config# ll #此目录下只有一个子目录 bash: ll: command not found root@testvolume:/etc/config# ls -l total 0 drwxrwxrwx 2 root root 6 Apr 12 02:11 app.properties root@testvolume:/etc/config# cat app.properties cat: app.properties: Is a directory root@testvolume:/etc/config# cd app.properties root@testvolume:/etc/config/app.properties# ls root@testvolume:/etc/config/app.properties# ls #此目录下为空 root@testvolume:/etc/config/app.properties#

    3.3无 subPath,path相当于重命名

    [root@k8s-master k8s-objs]# cat pod-configmap-testvolume.yaml
    apiVersion: v1
    kind: Pod
    metadata:
      labels:
        purpose: test-configmap-volume
      name: testvolume
    spec:
      containers:
        - name: test-configmap-volume
          image: tomcat:8
          imagePullPolicy: IfNotPresent
          #command: [ "/bin/sh", "-c", "echo $(MY_CACHE_HOST)" ]
          volumeMounts:
            - name: config-volume
              mountPath: /etc/config/app.properties ##此处app.properties为目录
    #          subPath: app.properties
      volumes:
        - name: config-volume
          configMap:
             name: test-cfg
             items:
               - key: cache_host
                 path: path/to/special-key-cache
               - key: app.properties
                 path: app-properties #此处path相当于更改文件名mv app.properties app-properties 
    [root@k8s-master k8s-objs]# 
    [root@k8s-master k8s-objs]# kubectl exec -it testvolume /bin/bash
    root@testvolume:/usr/local/tomcat# ls
    BUILDING.txt  CONTRIBUTING.md  LICENSE  NOTICE  README.md  RELEASE-NOTES  RUNNING.txt  bin  conf  include  lib  logs  native-jni-lib  temp  webapps  work
    root@testvolume:/usr/local/tomcat# cd /etc/config
    root@testvolume:/etc/config# ls
    app.properties
    root@testvolume:/etc/config# ls -l
    total 0
    drwxrwxrwx 3 root root 93 Apr 12 02:20 app.properties
    root@testvolume:/etc/config# cd app.properties
    root@testvolume:/etc/config/app.properties# ls
    app-properties  path
    root@testvolume:/etc/config/app.properties# ls -l
    total 0
    lrwxrwxrwx 1 root root 21 Apr 12 02:20 app-properties -> ..data/app-properties
    lrwxrwxrwx 1 root root 11 Apr 12 02:20 path -> ..data/path
    root@testvolume:/etc/config/app.properties# cat app-properties 
    property.1 = value-1
    property.2 = value-2
    property.3 = value-3
    root@testvolume:/etc/config/app.properties# cat path
    cat: path: Is a directory
    root@testvolume:/etc/config/app.properties# cd path
    root@testvolume:/etc/config/app.properties/path# ls
    to
    root@testvolume:/etc/config/app.properties/path# cd to
    root@testvolume:/etc/config/app.properties/path/to# ls -l
    total 4
    -rw-r--r-- 1 root root 9 Apr 12 02:20 special-key-cache
    root@testvolume:/etc/config/app.properties/path/to# cat special-key-cache 
    mysql-k8sroot@testvolume:/etc/config/app.properties/path/to# 

    3.4有subPath且筛选结果为true,mouthPath指定文件名,可以和subPath不一样

    [root@k8s-master k8s-objs]# vi pod-configmap-testvolume.yaml
    
    apiVersion: v1
    kind: Pod
    metadata:
      labels:
        purpose: test-configmap-volume
      name: testvolume
    spec:
      containers:
        - name: test-configmap-volume
          image: tomcat:8
          imagePullPolicy: IfNotPresent
          #command: [ "/bin/sh", "-c", "echo $(MY_CACHE_HOST)" ]
          volumeMounts:
            - name: config-volume
              mountPath: /etc/config/app.properties #此处app.properties为文件名
              subPath: app-properties #改为与mountPath不一样的文件名时,subPath相当于通过volume筛选configMap中的key(此处为因volumes.configMap.items.path对key进行了重命名)中的条目,即存在subPath时,subPath决定有无,mountPath决定文件名
      volumes:
        - name: config-volume
          configMap:
             name: test-cfg
             items:
               - key: cache_host
                 path: path/to/special-key-cache
               - key: app.properties
                 path: app-properties
    
    [root@k8s-master k8s-objs]# kubectl exec -it testvolume /bin/bash
    root@testvolume:/usr/local/tomcat# cd /etc/config
    root@testvolume:/etc/config# ls
    app.properties
    root@testvolume:/etc/config# ls -l
    total 4
    -rw-r--r-- 1 root root 63 Apr 12 02:43 app.properties
    root@testvolume:/etc/config# cat app.properties
    property.1 = value-1
    property.2 = value-2
    property.3 = value-3
    root@testvolume:/etc/config# pwd
    /etc/config
    root@testvolume:/etc/config# ls
    app.properties
    root@testvolume:/etc/config# exit

    3.5有subPath且筛选结果为true,mouthPath指定文件名,可以和subPath不一样,甚至随意指定为z.txt

    [root@k8s-master k8s-objs]# vi pod-configmap-testvolume.yaml
    
    apiVersion: v1
    kind: Pod
    metadata:
      labels:
        purpose: test-configmap-volume
      name: testvolume
    spec:
      containers:
        - name: test-configmap-volume
          image: tomcat:8
          imagePullPolicy: IfNotPresent
          #command: [ "/bin/sh", "-c", "echo $(MY_CACHE_HOST)" ]
          volumeMounts:
            - name: config-volume
              mountPath: /etc/config/z.txt #subPath决定有无,mountPath决定文件名为z.txt
              subPath: app-properties
      volumes:
        - name: config-volume
          configMap:
             name: test-cfg
             items:
               - key: cache_host
                 path: path/to/special-key-cache
               - key: app.properties
                 path: app-properties
    
    [root@k8s-master k8s-objs]# kubectl exec -it testvolume /bin/bash
    root@testvolume:/usr/local/tomcat# cd /etc/config
    root@testvolume:/etc/config# ls
    z.txt
    root@testvolume:/etc/config# pwd
    /etc/config
    root@testvolume:/etc/config# cat z.txt 
    property.1 = value-1
    property.2 = value-2
    property.3 = value-3
    root@testvolume:/etc/config# 

     

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  • 原文地址:https://www.cnblogs.com/pu20065226/p/10690628.html
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