configmap
是k8s的一個配置管理元件，可以將配置以key-value的形式傳遞，通常用來儲存不需要加密的配置資訊，加密資訊則需用到Secret，主要用來應對以下場景：
1. 使用k8s部署應用，當你將應用配置寫進程式碼中，就會存在一個問題，更新配置時也需要打包映象，configmap可以將配置資訊和docker映象解耦。
2. 使用微服務架構的話，存在多個服務共用配置的情況，如果每個服務中單獨一份配置的話，那麼更新配置就很麻煩，使用configmap可以友好的進行配置共享。
3. ConfigMap用於儲存配置資料的鍵值對，可以用來儲存單個屬性，也可以用來儲存配置檔案。
ConfigMap跟secret很類似，但它可以更方便地處理不包含敏感資訊的字串。比如應用的配置資訊
直接顯示
➜ ~ kubectl explain configmapKIND: ConfigMapVERSION: v1DESCRIPTION: ConfigMap holds configuration data for pods to consume.描述：ConfigMap儲存pod要使用的配置資料如果有kubectl proxy的話，地址如下
http://localhost:8001/api/v1/namespaces/kubernetes-dashboard/services/https:kubernetes-dashboard:/proxy/#/configmap/default/istio-ca-root-cert?namespace=default➜ ~ kubectl -n kube-system get configmapNAME DATA AGEcoredns 1 100dextension-apiserver-authentication 6 100distio-ca-root-cert 1 36dkube-proxy 2 100dkubeadm-config 2 100dkubelet-config-1.18 1 100d下面2個命令獲取目前的onfigmaps，如上也可以指定-n kube-system
➜ ~ kubectl get cmNAME DATA AGEistio-ca-root-cert 1 36d➜ ~ kubectl get configmapsNAME DATA AGEistio-ca-root-cert 1 36d可以檢視其現在的大概配置：kubectl get configmaps istio-ca-root-cert -o yaml可以使用kubectl create configmap
從檔案、目錄或者key-value字串建立等建立ConfigMap。
可以透過命令kubectl create configmap -h幫助資訊檢視具體的建立
Usage: kubectl create configmap NAME [--from-file=[key=]source][--from-literal=key1=value1] [--dry-run=server|client|none] [options]參考官方的：https://www.kubernetes.org.cn/configmap# 從key-value字串建立ConfigMap$ kubectl create configmap special-config --from-literal=special.how=veryconfigmap "special-config" created$ kubectl get configmap special-config -o go-template='{{.data}}'map[special.how:very]# 從env檔案建立$ echo -e "a=b\nc=d" | tee config.enva=bc=d$ kubectl create configmap special-config --from-env-file=config.envconfigmap "special-config" created$ kubectl get configmap special-config -o go-template='{{.data}}'map[a:b c:d]# 從目錄建立$ mkdir config$ echo a>config/a$ echo b>config/b$ kubectl create configmap special-config --from-file=config/configmap "special-config" created$ kubectl get configmap special-config -o go-template='{{.data}}'map[a:a b:b]現在我直接用命令建立
➜ ~ kubectl create configmap --help # Create a new configmap named my-config with key1=config1 and key2=config2 kubectl create configmap my-config --from-literal=key1=config1--from-literal=key2=config2➜ ~ kubectl create configmap nginx-nc --from-literal=nginx_port=80 --from-literal=nginx_server=map.snsyr.comconfigmap/nginx-nc created現在檢視下，23s還很新鮮 哈
➜ ~ kubectl get cmNAME DATA AGEistio-ca-root-cert 1 36dnginx-nc 2 23s具體再看下其yaml格式
➜ ~ kubectl get cm nginx-nc -o yamlapiVersion: v1data: nginx_port: "80" nginx_server: map.snsyr.comkind: ConfigMapmetadata: creationTimestamp: "2021-01-22T07:19:42Z" managedFields: - apiVersion: v1 fieldsType: FieldsV1 fieldsV1: f:data: .: {} f:nginx_port: {} f:nginx_server: {} manager: kubectl-create operation: Update time: "2021-01-22T07:19:42Z" name: nginx-nc namespace: default resourceVersion: "991620" selfLink: /api/v1/namespaces/default/configmaps/nginx-nc uid: c361edbb-7ed3-4a23-abdb-b4c4abfd3b51把value以檔案的方式存放，繼續參考配置
準備檔案：大致如下
➜ configmap pwd/Users/lex/Downloads/docker/configmap➜ configmap cat www.confserver { server_name file.snsyr.com; port 80; root /data/web/html;}Usage: kubectl create configmap NAME [--from-file=[key=]source][--from-literal=key1=value1] [--dry-run=server|client|none] [options]Use "kubectl options" for a list of global command-line options (applies to allcommands).➜ configmap pwd/Users/lex/Downloads/docker/configmap➜ configmap kubectl create configmap nginx-cm-from-file --from-file=./www.confconfigmap/nginx-cm-from-file created檢視下這個nginx-cm-from-file
➜ configmap kubectl get cmNAME DATA AGEistio-ca-root-cert 1 36dnginx-cm-from-file 1 15snginx-nc 2 8m32s 具體再看下其yaml格式
➜ configmap kubectl get cm nginx-cm-from-file -o yamlapiVersion: v1data: www.conf: | server { server_name file.snsyr.com; port 80; root /data/web/html; }kind: ConfigMapmetadata: creationTimestamp: "2021-01-22T07:27:59Z" managedFields: - apiVersion: v1 fieldsType: FieldsV1 fieldsV1: f:data: .: {} f:www.conf: {} manager: kubectl-create operation: Update time: "2021-01-22T07:27:59Z" name: nginx-cm-from-file namespace: default resourceVersion: "992679" selfLink: /api/v1/namespaces/default/configmaps/nginx-cm-from-file uid: cfc3bc22-cef1-468b-a37b-738b75a3a50f當然也可以用describe來檢視
➜ kubectl describe cm nginx-ncName: nginx-ncNamespace: defaultLabels: <none>Annotations: <none>Data====nginx_port:----80nginx_server:----map.snsyr.comEvents: <none>➜ kubectl describe cm nginx-cm-from-fileName: nginx-cm-from-fileNamespace: defaultLabels: <none>Annotations: <none>Data====www.conf:----server { server_name file.snsyr.com; port 80; root /data/web/html;}Events: <none>從env檔案建立我這裡不模擬了參考官方文件
https://www.kubernetes.org.cn/configmap
ConfigMap使用ConfigMap可以透過多種方式在Pod中使用，比如設定環境變數、設定容器命令列引數、在Volume中建立配置檔案等。
注意
ConfigMap必須在Pod引用它之前建立
使用envFrom時，將會自動忽略無效的鍵
Pod只能使用同一個名稱空間內的ConfigMap
針對上面的同一個名稱空間內的ConfigMap可以看到我的【Namespace: default】
kubectl get pods -n defaultNAME READY STATUS RESTARTS AGEdetails-v1-558b8b4b76-k46f8 2/2 Running 2 17dnginx-app-7fbf4688b7-mgv29 2/2 Running 18 29dnginx-app-7fbf4688b7-ps7qm 2/2 Running 18 29dproductpage-v1-6987489c74-pkpk9 2/2 Running 2 17dpython-app-6f6fd6fb6c-4zwxt 2/2 Running 10 24dpython-app-6f6fd6fb6c-w29n5 2/2 Running 10 24dratings-v1-7dc98c7588-bfvsr 2/2 Running 2 17dreviews-v1-7f99cc4496-rzzm6 2/2 Running 2 17dreviews-v2-7d79d5bd5d-59k87 2/2 Running 2 17dreviews-v3-7dbcdcbc56-jstnw 2/2 Running 2 17d建立一個pod 關聯剛剛建立的cm
➜ configmap pwd/Users/lex/Downloads/docker/configmap說明下： image: python:httpd這個我用我以前的image➜ configmap cat cm-1.ymlapiVersion: v1kind: Podmetadata: name: myapp-cm-1 namespace: default annotations: snsyr: "by snsyr"spec: containers: - name: myapp-cm-1 image: python:httpd ports: - name: http containerPort: 80 env: - name: nginx_port valueFrom: configMapKeyRef: name: nginx-nc key: nginx_port - name: nginx_server valueFrom: configMapKeyRef: name: nginx-nc key: nginx_server然後直接建立：
➜ configmap kubectl apply -f cm-1.ymlpod/myapp-cm-1 created檢視下剛才建立的pod
➜ configmap kubectl get podsNAME READY STATUS RESTARTS AGEdetails-v1-558b8b4b76-k46f8 2/2 Running 2 17dmyapp-cm-1 0/2 PodInitializing 0 28snginx-app-7fbf4688b7-mgv29 2/2 Running 18 29dnginx-app-7fbf4688b7-ps7qm 2/2 Running 18 29dproductpage-v1-6987489c74-pkpk9 2/2 Running 2 17dpython-app-6f6fd6fb6c-4zwxt 2/2 Running 10 24dpython-app-6f6fd6fb6c-w29n5 2/2 Running 10 24dratings-v1-7dc98c7588-bfvsr 2/2 Running 2 17dreviews-v1-7f99cc4496-rzzm6 2/2 Running 2 17dreviews-v2-7d79d5bd5d-59k87 2/2 Running 2 17dreviews-v3-7dbcdcbc56-jstnw 2/2 Running 2 17d檢視狀態PodInitializing變成Running之後，進入pod核對下資訊：
kubectl exec -it myapp-cm-1 -- /bin/sh ➜ kubectl exec -it myapp-cm-1 -- /bin/shDefaulting container name to myapp-cm-1.Use 'kubectl describe pod/myapp-cm-1 -n default' to see all of the containers in this pod.直接檢視環境變數：# env|grep nginx_portnginx_port=80# env|grep nginx_servernginx_server=map.snsyr.com執行命令：
kubectl edit configmap nginx-nc完成之後： # Please edit the object below. Lines beginning with a '#' will be ignored, # and an empty file will abort the edit. If an error occurs while saving this file will be # reopened with the relevant failures. # apiVersion: v1 data: nginx_port: "8083" nginx_server: map.snsyr.com kind: ConfigMap metadata: creationTimestamp: "2021-01-22T07:19:42Z" name: nginx-nc namespace: default resourceVersion: "991620" selfLink: /api/v1/namespaces/default/configmaps/nginx-nc uid: c361edbb-7ed3-4a23-abdb-b4c4abfd3b51提示如下
configmap/nginx-nc edited
再次進入pod檢視我的環境變數
➜ configmap kubectl exec -it myapp-cm-1 -- /bin/shDefaulting container name to myapp-cm-1.Use 'kubectl describe pod/myapp-cm-1 -n default' to see all of the containers in this pod.# env|grep nginx_portnginx_port=80# env|grep nginx_servernginx_server=map.snsyr.com沒有變化：
說明：即使修改了configmap ,pod中的環境變數只會在第一次建立時生效，即使重啟pod也不會生效，後期修改不會生效
測試基於儲存卷的的 pod 引用環境變數是否變化我的環境中有 image: python:httpd這個映象，所以直接拿來測試
➜ configmap pwd/Users/lex/Downloads/docker/configmap➜ configmap cat volume.yamlapiVersion: v1kind: Podmetadata: name: myappcentos namespace: default annotations: snsyr: "by snsyr"spec: containers: - name: myappcentos image: python:httpd ports: - name: http containerPort: 80 volumeMounts: - name: nginx-conf mountPath: /etc/nginx/conf.d/ volumes: - name: nginx-conf configMap: name: nginx-cm-from-file啟動：
➜ configmap kubectl apply -f volume.yamlpod/myappcentos created➜ configmap kubectl get podsNAME READY STATUS RESTARTS AGEdetails-v1-558b8b4b76-k46f8 2/2 Running 2 17dmyapp-cm-1 2/2 Running 0 26mmyappcentos 0/2 PodInitializing 0 25s檢視狀態：當Init:0/1=PodInitializing等待狀態Running
進入容器檢視 環境變數
➜ configmap kubectl exec -it myappcentos -- /bin/shDefaulting container name to myappcentos.Use 'kubectl describe pod/myappcentos -n default' to see all of the containers in this pod.# ls /etc/nginx/conf.dwww.conf# cat /etc/nginx/conf.d/www.confserver { server_name file.snsyr.com; port 80; root /data/web/html;}現在在外部嘗試修改configmap 的埠為8080
➜ ~ kubectl edit cm nginx-cm-from-fileconfigmap/nginx-cm-from-file edited # Please edit the object below. Lines beginning with a '#' will be ignored, # and an empty file will abort the edit. If an error occurs while saving this file will be # reopened with the relevant failures. # apiVersion: v1 data: www.conf: | server { server_name file.snsyr.com; port 8080; root /data/web/html; } kind: ConfigMap metadata: creationTimestamp: "2021-01-22T07:27:59Z" name: nginx-cm-from-file namespace: default resourceVersion: "992679" selfLink: /api/v1/namespaces/default/configmaps/nginx-cm-from-file uid: cfc3bc22-cef1-468b-a37b-738b75a3a50f再次進入容器檢視環境變數，已經動態改變
➜ configmap kubectl exec -it myappcentos -- /bin/shDefaulting container name to myappcentos.Use 'kubectl describe pod/myappcentos -n default' to see all of the containers in this pod.# cat /etc/nginx/conf.d/www.confserver { server_name file.snsyr.com; port 8080; root /data/web/html;}綜上：詳細的測試參考：
https://www.kubernetes.org.cn/configmap
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