[英]In kubernetes, How to access the environment variable inside the configmap?
我有用例將 pod 名稱附加到“ jdbc_db_url ”屬性中。 位於“ common-configmap.config ”文件中。 為了實現,我遵循了以下步驟,但不幸的是無法做到。
第 1 步: common-configmap.config
# Database Properties
jdbc_auto_commit=false
jdbc_postgresql_driverClassName=org.postgresql.Driver
jdbc_db_url=jdbc:postgresql://dev.postgres.database.azure.com/dbname?ApplicationName=${POD_NAME}
第 2 步:使用以下命令將 configmap 部署到集群中
kubectl create configmap common-configmap --from-env-file /app/conf/common-configmap.config -n default
第 3 步:使用以下清單文件創建“myapp”容器和服務
部署清單文件:
apiVersion: apps/v1
kind: Deployment
metadata:
annotations:
deployment.kubernetes.io/revision: "1"
meta.helm.sh/release-name: master
meta.helm.sh/release-namespace: default
generation: 1
labels:
app.kubernetes.io/instance: master
app.kubernetes.io/managed-by: Helm
app.kubernetes.io/name: myapp
app.kubernetes.io/version: 4.0.0
helm.sh/chart: myapp-4.0.0
name: myapp
namespace: default
spec:
progressDeadlineSeconds: 600
replicas: 5
revisionHistoryLimit: 10
selector:
matchLabels:
app.kubernetes.io/instance: master
app.kubernetes.io/name: myapp
strategy:
rollingUpdate:
maxSurge: 25%
maxUnavailable: 25%
type: RollingUpdate
template:
metadata:
annotations:
sidecar.istio.io/inject: "true"
labels:
app.kubernetes.io/instance: master
app.kubernetes.io/name: myapp
spec:
containers:
- env:
- name: POD_NAME
valueFrom:
fieldRef:
fieldPath: metadata.name
envFrom:
- configMapRef:
name: myapp-configmap
- configMapRef:
name: common-configmap
image: docker.com/myapp:4.0.0
imagePullPolicy: Always
name: myapp
ports:
- containerPort: 8080
name: http
protocol: TCP
resources: {}
dnsPolicy: ClusterFirst
restartPolicy: Always
服務清單文件:
apiVersion: v1
kind: Service
metadata:
annotations:
meta.helm.sh/release-name: master
meta.helm.sh/release-namespace: default
labels:
app.kubernetes.io/instance: master
app.kubernetes.io/managed-by: Helm
app.kubernetes.io/name: myapp
app.kubernetes.io/version: 4.0.0
helm.sh/chart: myapp-4.0.0
name: myapp
namespace: default
spec:
ports:
- name: http
port: 8080
protocol: TCP
targetPort: http
selector:
app.kubernetes.io/instance: master
app.kubernetes.io/name: myapp
sessionAffinity: None
type: ClusterIP
驗證結果我進入了一個 shell 運行容器並打印了環境變量:
kubectl exec --stdin --tty myapp-d5db776b9-h25q5 -c myapp -- /bin/sh
實際結果:
# printenv
jdbc_auto_commit=false
jdbc_postgresql_driverClassName=org.postgresql.Driver
jdbc_db_url=jdbc:postgresql://dev.postgres.database.azure.com/dbname?ApplicationName=${POD_NAME}
預期結果:
jdbc_auto_commit=false
jdbc_postgresql_driverClassName=org.postgresql.Driver
jdbc_db_url=jdbc:postgresql://dev.postgres.database.azure.com/dbname?ApplicationName=myapp-d5db776b9-h25q5
如何在部署/容器運行時替換 config-map 中的環境變量? 或者有沒有其他方法可以在JDBC_URL中傳遞/替換pod_name
我可以知道,在這種情況下我做錯了什么?
預先感謝您的幫助。
您可以使用 init-container 來做到這一點,該容器在它和您的主容器之間具有類型為emptyDir
的共享卷。
首先,編輯您的部署以添加一個emptyDir
卷和一個 init 容器,並將該卷掛載到兩個容器:
apiVersion: apps/v1
kind: Deployment
metadata:
annotations:
deployment.kubernetes.io/revision: "1"
meta.helm.sh/release-name: master
meta.helm.sh/release-namespace: default
generation: 1
labels:
app.kubernetes.io/instance: master
app.kubernetes.io/managed-by: Helm
app.kubernetes.io/name: myapp
app.kubernetes.io/version: 4.0.0
helm.sh/chart: myapp-4.0.0
name: myapp
namespace: default
spec:
progressDeadlineSeconds: 600
replicas: 5
revisionHistoryLimit: 10
selector:
matchLabels:
app.kubernetes.io/instance: master
app.kubernetes.io/name: myapp
strategy:
rollingUpdate:
maxSurge: 25%
maxUnavailable: 25%
type: RollingUpdate
template:
metadata:
annotations:
sidecar.istio.io/inject: "true"
labels:
app.kubernetes.io/instance: master
app.kubernetes.io/name: myapp
spec:
volumes: # emptyDir volume for the entire pod
- name: config-volume
emptyDir: {}
initContainers: # an init container that will compile the env var with the pod name
- name: config-compiler
image: bash
volumeMounts:
- name: config-compiler
mountPath: /configs
env:
- name: POD_NAME
valueFrom:
fieldRef:
fieldPath: metadata.name
envFrom:
- configMapRef:
name: common-configmap
command:
- bash
- -c
- 'echo $jdbc_db_url | sed "s/POD_NAME/${POD_NAME}/" > /configs/compiled.env'
containers:
- volumeMounts:
- name: config-compiler
mountPath: /configs
env:
- name: POD_NAME
valueFrom:
fieldRef:
fieldPath: metadata.name
envFrom:
- configMapRef:
name: myapp-configmap
- configMapRef:
name: common-configmap
image: docker.com/myapp:4.0.0
imagePullPolicy: Always
name: myapp
ports:
- containerPort: 8080
name: http
protocol: TCP
resources: {}
dnsPolicy: ClusterFirst
restartPolicy: Always
然后,您需要確保您的實際 pod 正在讀取 env vars 文件 - 您可以通過編輯入口點腳本來添加如下一行:
source /configs/compiled.env
或將 pod 的命令編輯為如下所示:
command: [ 'source', '/configs/compiled.env;', 'previous-command' ]
以上兩者都有點hack-ish - 所以我建議做的是查看您的應用程序默認讀取哪些配置文件,並將您的編譯腳本與這些文件相匹配。
例如,如果您的應用程序從/etc/myapp/confs.d/files.env
讀取 - 將您的空目錄掛載到/etc/myapp/confs.d
並將初始化容器寫入files.env
,並在格式化你的應用程序(例如,如果它是一個 ini 文件而不是一個 env 文件,編譯它以便它匹配該格式)
顯然有更好的方法來編譯配置文件然后使用sed
- 但如果你想(並且負擔得起)保持簡短,這是一個選擇
一種直接的方法是在部署中使用一個簡單的命令,假設 JDBC_URL 值將僅在示例 pod 中使用。 否則,您可以在自定義基礎映像中或在 init 容器中使用類似的邏輯(如果有的話)。
apiVersion: apps/v1
kind: Deployment
metadata:
annotations:
deployment.kubernetes.io/revision: "1"
meta.helm.sh/release-name: master
meta.helm.sh/release-namespace: default
generation: 1
labels:
app.kubernetes.io/instance: master
app.kubernetes.io/managed-by: Helm
app.kubernetes.io/name: myapp
app.kubernetes.io/version: 4.0.0
helm.sh/chart: myapp-4.0.0
name: myapp
namespace: default
spec:
progressDeadlineSeconds: 600
replicas: 5
revisionHistoryLimit: 10
selector:
matchLabels:
app.kubernetes.io/instance: master
app.kubernetes.io/name: myapp
strategy:
rollingUpdate:
maxSurge: 25%
maxUnavailable: 25%
type: RollingUpdate
template:
metadata:
annotations:
sidecar.istio.io/inject: "true"
labels:
app.kubernetes.io/instance: master
app.kubernetes.io/name: myapp
spec:
containers:
- env:
- name: POD_NAME
valueFrom:
fieldRef:
fieldPath: metadata.name
envFrom:
- configMapRef:
name: myapp-configmap
- configMapRef:
name: common-configmap
image: docker.com/myapp:4.0.0
imagePullPolicy: Always
name: myapp
command:
- bash
- -c
- export JDBC_URL=$(echo $JDBC_URL | sed "s/POD_NAME/${POD_NAME}/1")
ports:
- containerPort: 8080
name: http
protocol: TCP
resources: {}
dnsPolicy: ClusterFirst
restartPolicy: Always
請注意我插入的代碼片段:
command:
- bash
- -c
- export JDBC_URL=$(echo $JDBC_URL | sed "s/POD_NAME/${POD_NAME}/1")
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