官网链接为 https://kubernetes.io/docs/tasks/configure-pod-container/assign-memory-resource/#create-a-namespace

操作环境为minikube，需要提前执行下列操作启用metrics-server服务

minikube addons enable metrics-server

使用下列命令可以查看是否开启

kubectl get apiservices | grep metrics

大致流程，原理等需要参考https://kubernetes.io/docs/tasks/configure-pod-container/assign-memory-resource/#create-a-namespace 下内容

# 下载一个redis的配置文件
➜ curl -OL https://k8s.io/examples/pods/config/redis-config

  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100   185  100   185    0     0     51      0  0:00:03  0:00:03 --:--:--    51
100    43  100    43    0     0     11      0  0:00:03  0:00:03 --:--:--   183
➜ ls
a.dockerfile a.tar        b.tar        redis-config server.js

# 使用kubectl create configmap命令创建一个configmap文件
➜ kubectl create configmap example-redis-config --from-file=redis-config
configmap "example-redis-config" created

# 将configmap文件输出为yaml
➜ kubectl get configmap example-redis-config -o yaml
apiVersion: v1
data:
  redis-config: 
    maxmemory 2mb
    maxmemory-policy allkeys-lru
kind: ConfigMap
metadata:
  creationTimestamp: 2019-03-19T08:51:28Z
  name: example-redis-config
  namespace: default
  resourceVersion: "34018"
  selfLink: /api/v1/namespaces/default/configmaps/example-redis-config
  uid: 2f58973b-4a24-11e9-b7b5-080027d6b830


# 根据redis-pod.yaml文件来创建一个pod
➜ kubectl create -f https://k8s.io/examples/pods/config/redis-pod.yaml
pod "redis" created

➜ kubectl get pods
NAME                                 READY     STATUS              RESTARTS   AGE
kubernetes-bootcamp-b4d449bd-vlnpd   1/1       Running             0          1h
redis                                0/1       ContainerCreating   0          36m

# redis-pod.yaml文件的内容如下，可以看到volumes下面的configMap就是来自于上面创建的configMap
# 而configMap来自于最早的redis-config

apiVersion: v1
kind: Pod
metadata:
  name: redis
spec:
  containers:
  - name: redis
    image: kubernetes/redis:v1
    env:
    - name: MASTER
      value: "true"
    ports:
    - containerPort: 6379
    resources:
      limits:
        cpu: "0.1"
    volumeMounts:
    - mountPath: /redis-master-data
      name: data
    - mountPath: /redis-master
      name: config
  volumes:
    - name: data
      emptyDir: {}
    - name: config
      configMap:
        name: example-redis-config
        items:
        - key: redis-config
          path: redis.conf