Kubernetes-1.13 部署metric-server 笔记
Kubernetes 1.8开始，Kubernetes通过Metrics API提供资源使用指标，例如容器CPU和内存使用。同时heapster 已被 Kubernetes 弃用。以下为 metrics-server 的折腾记录。
首先在来执行下下面命令，发现它找不请求源数据，这是因为没有为系统提供数据源。
$ k top node
Error from server (NotFound): the server could not find the requested resource (get services http:heapster:)
部署metric-server
克隆仓库
$ git clone https://github.com/kubernetes-incubator/metrics-server.git
$ cd metrics-server
编辑配置文件，将deploy 的文件改成国内镜像，并将imagePullPolicy改成 IfNotPresent
---
apiVersion: v1
kind: ServiceAccount
metadata:
name: metrics-server
namespace: kube-system
---
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
name: metrics-server
namespace: kube-system
labels:
k8s-app: metrics-server
spec:
selector:
matchLabels:
k8s-app: metrics-server
template:
metadata:
name: metrics-server
labels:
k8s-app: metrics-server
spec:
serviceAccountName: metrics-server
volumes:
# mount in tmp so we can safely use from-scratch images and/or read-only containers
- name: tmp-dir
emptyDir: {}
containers:
- name: metrics-server
### 更改为国内镜像
image: registry.cn-shenzhen.aliyuncs.com/shuhui/metrics-server:v0.3.1
### 改成 IfNotPresent
imagePullPolicy: IfNotPresent
### 追加，忽略证书验证，否则报错
command:
- /metrics-server
- --kubelet-insecure-tls
volumeMounts:
- name: tmp-dir
mountPath: /tmp
编辑清单文件后，部署metrics-server
$ k create -f deploy/1.8+/
查看部署情况
$ k describe deployments.apps -n kube-system metrics-server
Name: metrics-server
Namespace: kube-system
...
Type Reason Age From Message
---- ------ ---- ---- -------
Normal ScalingReplicaSet 16m deployment-controller Scaled up replica set metrics-server-7c5b49ff5c to 1
Normal ScalingReplicaSet 16m deployment-controller Scaled down replica set metrics-server-5f5cd8dc65 to 0
测试
这时候，metric-server虽然部署完了，继续执行查询节点使用资源时，你会发现换种报错方式了。
$ k top node
error: metrics not available yet
查看 metrics-server 的日志
$ k logs -n kube-system metrics-server-879f5ff6d-l2lxr
I0130 08:57:53.278112 1 serving.go:273] Generated self-signed cert (apiserver.local.config/certificates/apiserver.crt, apiserver.local.config/certificates/apiserver.key)
[restful] 2019/01/30 08:57:53 log.go:33: [restful/swagger] listing is available at https://:443/swaggerapi
[restful] 2019/01/30 08:57:53 log.go:33: [restful/swagger] https://:443/swaggerui/ is mapped to folder /swagger-ui/
I0130 08:57:53.942207 1 serve.go:96] Serving securely on [::]:443
E0130 08:57:58.338932 1 reststorage.go:129] unable to fetch node metrics for node "bs-02-yf-hw2288v3-11.wd.local": no metrics known for node
可以看出无法解析到bs-02-yf-hw2288v3-11.wd.local这个域名，这个域名在本机是可以解析的。
$ ping -c 1 bs-02-yf-hw2288v3-11.wd.local
PING bs-02-yf-hw2288v3-11.wd.local (192.168.50.11) 56(84) bytes of data.
64 bytes from bs-02-yf-hw2288v3-11.wd.local (192.168.50.11): icmp_seq=1 ttl=64 time=0.043 ms
--- bs-02-yf-hw2288v3-11.wd.local ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 0.043/0.043/0.043/0.000 ms
于是，我们为 metircs-server 手动添加这条DNS 记录
$ k edit -n kube-system deployments.apps metrics-server
<省略若干行>
containers:
- command:
- /metrics-server
- --kubelet-insecure-tls
- --kubelet-preferred-address-types=InternalIP
image: k8s.gcr.io/metrics-server-amd64:v0.3.1
<省略若干行>
保存，继续执行以下命令
$ k top nodes
NAME CPU(cores) CPU% MEMORY(bytes) MEMORY%
bs-02-yf-hw2288v3-11.wd.local 178m 0% 5811Mi 9%
$ k top nodes
嗯，一切顺利，有了它的存在，可以自由部署 HPA了。
metrics-server默认使用node的主机名,所以CoreDNS无法解析到这个域名的IP，可以在集群初始化的时候加上 --node-name=$(hostname -i)，也可以在上游的DNS 添加这个主机的解析。
