本文通过环境变量将 Pod 信息呈现给容器
用 Pod 字段作为环境变量的值
这个配置文件中，你可以看到五个环境变量。env 字段是一个 EnvVars. 对象的数组。 数组中第一个元素指定 MY_NODE_NAME 这个环境变量从 Pod 的 spec.nodeName 字段获取变量值。 同样，其它环境变量也是从 Pod 的字段获取它们的变量值。
说明： 本示例中的字段是 Pod 字段，不是 Pod 中 Container 的字段。
apiVersion: apps/v1
kind: Deployment
metadata:
labels:
k8s-app: dapi-envars-fieldref
name: dapi-envars-fieldref
namespace: default
spec:
selector:
matchLabels:
k8s-app: dapi-envars-fieldref
template:
metadata:
labels:
k8s-app: dapi-envars-fieldref
spec:
containers:
- args:
- while true; do echo -en '\n'; printenv MY_NODE_NAME MY_POD_NAME MY_POD_NAMESPACE; printenv MY_POD_IP MY_POD_SERVICE_ACCOUNT; sleep 10;done;
command:
- sh
- -c
env:
- name: MY_NODE_NAME
valueFrom:
fieldRef:
apiVersion: v1
fieldPath: spec.nodeName
- name: MY_POD_NAME
valueFrom:
fieldRef:
apiVersion: v1
fieldPath: metadata.name
- name: MY_POD_NAMESPACE
valueFrom:
fieldRef:
apiVersion: v1
fieldPath: metadata.namespace
- name: MY_POD_IP
valueFrom:
fieldRef:
apiVersion: v1
fieldPath: status.podIPs
- name: MY_POD_SERVICE_ACCOUNT
valueFrom:
fieldRef:
apiVersion: v1
fieldPath: spec.serviceAccountName
image: busybox
imagePullPolicy: IfNotPresent
name: dapi-envars-fieldref
resources: {}
用 Container 字段作为环境变量的值
前面的练习中，你将 Pod 字段作为环境变量的值。 接下来这个练习中，你将用 Container 字段作为环境变量的值。这里是包含一个容器的 Pod 的配置文件
apiVersion: apps/v1
kind: Deployment
metadata:
labels:
k8s-app: dapi-envars-container
name: dapi-envars-container
namespace: default
spec:
replicas: 1
selector:
matchLabels:
k8s-app: dapi-envars-container
template:
metadata:
labels:
k8s-app: dapi-envars-container
spec:
containers:
- args:
- while true; do echo -en '\n'; printenv MY_CPU_REQUEST MY_CPU_LIMIT;printenv MY_MEM_REQUEST MY_MEM_LIMIT;sleep 10;done;
command:
- sh
- -c
env:
- name: MY_CPU_REQUEST
valueFrom:
resourceFieldRef:
containerName: test-container
divisor: "1"
resource: requests.cpu
- name: MY_CPU_LIMIT
valueFrom:
resourceFieldRef:
containerName: test-container
divisor: "1"
resource: limits.cpu
- name: MY_MEM_REQUEST
valueFrom:
resourceFieldRef:
containerName: test-container
divisor: "1"
resource: requests.memory
- name: MY_MEM_LIMIT
valueFrom:
resourceFieldRef:
containerName: test-container
divisor: "1"
resource: limits.memory
image: busybox:1.24
imagePullPolicy: IfNotPresent
name: test-container
resources:
limits:
cpu: 200m
memory: 128Mi
requests:
cpu: 100m
memory: 64Mi
这个配置文件中，你可以看到四个环境变量。env 字段是一个 EnvVars. 对象的数组。数组中第一个元素指定 MY_CPU_REQUEST 这个环境变量从 Container 的 requests.cpu 字段获取变量值。同样，其它环境变量也是从 Container 的字段获取它们的变量值。
说明： 本例中使用的是 Container 的字段而不是 Pod 的字段。
通过文件将 Pod 信息呈现给容器
此页面描述 Pod 如何使用 DownwardAPIVolumeFile 把自己的信息呈现给 Pod 中运行的容器。 DownwardAPIVolumeFile 可以呈现 Pod 的字段和容器字段
apiVersion: apps/v1
kind: Deployment
metadata:
labels:
k8s-app: kubernetes-downwardapi-volume-example
name: kubernetes-downwardapi-volume-example
namespace: default
spec:
selector:
matchLabels:
k8s-app: kubernetes-downwardapi-volume-example
template:
metadata:
labels:
k8s-app: kubernetes-downwardapi-volume-example
spec:
containers:
- args:
- while true; do if [[ -e /etc/podinfo/labels ]]; then echo -en '\n\n'; cat /etc/podinfo/labels; fi; if [[ -e /etc/podinfo/annotations ]]; then echo -en '\n\n'; cat /etc/podinfo/annotations; fi; sleep 5;done;
command:
- sh
- -c
image: busybox
imagePullPolicy: IfNotPresent
name: client-container
resources: {}
volumeMounts:
- name: podinfo
mountPath: /etc/podinfo
volumes:
- name: podinfo
downwardAPI:
items:
- path: "labels"
fieldRef:
fieldPath: metadata.labels
- path: "annotations"
fieldRef:
fieldPath: metadata.annotations
Downward API支持的常用字段
1，使用fieldRef可以声明使用:
spec.nodeName - 宿主机名字
status.hostIP - 宿主机IP
metadata.name - Pod的名字
metadata.namespace - Pod的Namespace
status.podIP - Pod的IP
spec.serviceAccountName - Pod的Service Account的名字
metadata.uid - Pod的UID
metadata.labels['
metadata.annotations['
metadata.labels - Pod的所有Label
metadata.annotations - Pod的所有Annotation
2，使用resourceFieldRef可以声明使用:
limits.cpu-容器的CPU limit
requests.cpu-容器的CPU request
limits.memory-容器的memory limit
requests.memory容器的memory request
完整示例：
apiVersion: apps/v1
kind: Deployment
metadata:
labels:
k8s-app: centos-env
qcloud-app: centos-env
name: centos-env
spec:
selector:
matchLabels:
k8s-app: centos-env
template:
metadata:
annotations:
description: ddd
labels:
k8s-app: centos-env
qcloud-app: centos-env
spec:
containers:
- env:
- name: pod-name
valueFrom:
fieldRef:
apiVersion: v1
fieldPath: metadata.name
- name: pod-namespacce
valueFrom:
fieldRef:
apiVersion: v1
fieldPath: metadata.namespace
- name: pod-labels
valueFrom:
fieldRef:
apiVersion: v1
fieldPath: metadata.labels['k8s-app']
- name: pod-annotations
valueFrom:
fieldRef:
apiVersion: v1
fieldPath: metadata.annotations['description']
- name: pod-uid
valueFrom:
fieldRef:
apiVersion: v1
fieldPath: metadata.uid
- name: pod-nodename
valueFrom:
fieldRef:
apiVersion: v1
fieldPath: spec.nodeName
- name: pod-hostIP
valueFrom:
fieldRef:
apiVersion: v1
fieldPath: status.hostIP
- name: pod-podIP
valueFrom:
fieldRef:
apiVersion: v1
fieldPath: status.podIP
- name: pod-serviceAccountName
valueFrom:
fieldRef:
apiVersion: v1
fieldPath: spec.serviceAccountName
image: ccr.ccs.tencentyun.com/chenjingwei/centos:latest
imagePullPolicy: IfNotPresent
name: centos-1
resources:
limits:
cpu: 25m
memory: 64Mi
requests:
cpu: 25m
memory: 64Mi
volumeMounts:
- mountPath: /etc/podinfo
name: podinfo
readOnly: false
imagePullSecrets:
- name: qcloudregistrykey
volumes:
- name: podinfo
projected:
sources:
- downwardAPI:
items:
- path: "labels"
fieldRef:
fieldPath: metadata.labels
- path: "annotations"
fieldRef:
fieldPath: metadata.annotations