[root@tt-fc-dev01.nj etcd]# ss -tlpn|grep apiserver
LISTEN 0      128                *:6443             *:*    users:(("kube-apiserver",pid=164445,fd=7))

[root@tt-fc-dev01.nj etcd]# curl -s http://localhost:6443/metrics
Client sent an HTTP request to an HTTPS server.

[root@tt-fc-dev01.nj etcd]# curl -s -k https://localhost:6443/metrics
{
  "kind": "Status",
  "apiVersion": "v1",
  "metadata": {},
  "status": "Failure",
  "message": "forbidden: User \"system:anonymous\" cannot get path \"/metrics\"",
  "reason": "Forbidden",
  "details": {},
  "code": 403
}

---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: categraf
rules:
  - apiGroups: [""]
    resources:
      - nodes
      - nodes/metrics
      - nodes/stats
      - nodes/proxy
      - services
      - endpoints
      - pods
    verbs: ["get", "list", "watch"]
  - apiGroups:
      - extensions
      - networking.k8s.io
    resources:
      - ingresses
    verbs: ["get", "list", "watch"]
  - nonResourceURLs: ["/metrics", "/metrics/cadvisor"]
    verbs: ["get"]
---
apiVersion: v1
kind: ServiceAccount
metadata:
  name: categraf
  namespace: flashcat
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: categraf
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: categraf
subjects:
- kind: ServiceAccount
  name: categraf
  namespace: flashcat

[root@tt-fc-dev01.nj yamls]# kubectl apply -f auth-server.yaml -n flashcat
clusterrole.rbac.authorization.k8s.io/categraf unchanged
serviceaccount/categraf unchanged
clusterrolebinding.rbac.authorization.k8s.io/categraf unchanged

[root@tt-fc-dev01.nj yamls]# kubectl get sa categraf -n flashcat
NAME       SECRETS   AGE
categraf   1         7h13m

[root@tt-fc-dev01.nj yamls]# kubectl get sa categraf -n flashcat -o yaml
apiVersion: v1
kind: ServiceAccount
metadata:
  annotations:
    kubectl.kubernetes.io/last-applied-configuration: |
      {"apiVersion":"v1","kind":"ServiceAccount","metadata":{"annotations":{},"name":"categraf","namespace":"flashcat"}}
  creationTimestamp: "2022-11-28T05:00:17Z"
  name: categraf
  namespace: flashcat
  resourceVersion: "127151612"
  uid: 8b473b31-ce09-4abe-ae55-ea799160a9d5
secrets:
- name: categraf-token-6whbs

[root@tt-fc-dev01.nj yamls]# kubectl get secret categraf-token-6whbs -n flashcat
NAME                   TYPE                                  DATA   AGE
categraf-token-6whbs   kubernetes.io/service-account-token   3      7h15m

[root@tt-fc-dev01.nj yamls]# token=`kubectl get secret categraf-token-6whbs -n flashcat -o jsonpath={.data.token} | base64 -d`
[root@tt-fc-dev01.nj yamls]# curl -s -k -H "Authorization: Bearer $token" https://localhost:6443/metrics > metrics
[root@tt-fc-dev01.nj yamls]# head -n 6 metrics
# HELP aggregator_openapi_v2_regeneration_count [ALPHA] Counter of OpenAPI v2 spec regeneration count broken down by causing APIService name and reason.
# TYPE aggregator_openapi_v2_regeneration_count counter
aggregator_openapi_v2_regeneration_count{apiservice="*",reason="startup"} 0
aggregator_openapi_v2_regeneration_count{apiservice="k8s_internal_local_delegation_chain_0000000002",reason="update"} 0
aggregator_openapi_v2_regeneration_count{apiservice="v1beta1.metrics.k8s.io",reason="add"} 0
aggregator_openapi_v2_regeneration_count{apiservice="v1beta1.metrics.k8s.io",reason="update"} 0

apiVersion: v1
kind: ConfigMap
metadata:
  name: prometheus-agent-conf
  labels:
    name: prometheus-agent-conf
  namespace: flashcat
data:
  prometheus.yml: |-
    global:
      scrape_interval: 15s
      evaluation_interval: 15s
    scrape_configs:
      - job_name: 'apiserver'
        kubernetes_sd_configs:
        - role: endpoints
        scheme: https
        tls_config:
          insecure_skip_verify: true
        authorization:
          credentials_file: /var/run/secrets/kubernetes.io/serviceaccount/token
        relabel_configs:
        - source_labels: [__meta_kubernetes_namespace, __meta_kubernetes_service_name, __meta_kubernetes_endpoint_port_name]
          action: keep
          regex: default;kubernetes;https
    remote_write:
    - url: 'http://10.206.0.16:19000/prometheus/v1/write'    

apiVersion: apps/v1
kind: Deployment
metadata:
  name: prometheus-agent
  namespace: flashcat
  labels:
    app: prometheus-agent
spec:
  replicas: 1
  selector:
    matchLabels:
      app: prometheus-agent
  template:
    metadata:
      labels:
        app: prometheus-agent
    spec:
      serviceAccountName: categraf
      containers:
        - name: prometheus
          image: prom/prometheus
          args:
            - "--config.file=/etc/prometheus/prometheus.yml"
            - "--web.enable-lifecycle"
            - "--enable-feature=agent"
          ports:
            - containerPort: 9090
          resources:
            requests:
              cpu: 500m
              memory: 500M
            limits:
              cpu: 1
              memory: 1Gi
          volumeMounts:
            - name: prometheus-config-volume
              mountPath: /etc/prometheus/
            - name: prometheus-storage-volume
              mountPath: /prometheus/
      volumes:
        - name: prometheus-config-volume
          configMap:
            defaultMode: 420
            name: prometheus-agent-conf
        - name: prometheus-storage-volume
          emptyDir: {}

[work@tt-fc-dev01.nj yamls]$ kubectl apply -f prometheus-agent-deployment.yaml
deployment.apps/prometheus-agent created

# HELP apiserver_request_duration_seconds [STABLE] Response latency distribution in seconds for each verb, dry run value, group, version, resource, subresource, scope and component.
# TYPE apiserver_request_duration_seconds histogram
apiserver响应的时间分布，按照url 和 verb 分类
一般按照instance和verb+时间 汇聚

# HELP apiserver_request_total [STABLE] Counter of apiserver requests broken out for each verb, dry run value, group, version, resource, scope, component, and HTTP response code.
# TYPE apiserver_request_total counter
apiserver的请求总数，按照verb、 version、 group、resource、scope、component、 http返回码分类统计

# HELP apiserver_current_inflight_requests [STABLE] Maximal number of currently used inflight request limit of this apiserver per request kind in last second.
# TYPE apiserver_current_inflight_requests gauge
最大并发请求数, 按mutating(非get list watch的请求)和readOnly(get list watch)分别限制
超过max-requests-inflight(默认值400)和max-mutating-requests-inflight(默认200)的请求会被限流
apiserver变更时要注意观察，也是反馈集群容量的一个重要指标

# HELP apiserver_response_sizes [STABLE] Response size distribution in bytes for each group, version, verb, resource, subresource, scope and component.
# TYPE apiserver_response_sizes histogram
apiserver 响应大小，单位byte, 按照verb、 version、 group、resource、scope、component分类统计

# HELP watch_cache_capacity [ALPHA] Total capacity of watch cache broken by resource type.
# TYPE watch_cache_capacity gauge
按照资源类型统计的watch缓存大小

# HELP process_cpu_seconds_total Total user and system CPU time spent in seconds.
# TYPE process_cpu_seconds_total counter
每秒钟用户态和系统态cpu消耗时间, 计算apiserver进程的cpu的使用率

# HELP process_resident_memory_bytes Resident memory size in bytes.
# TYPE process_resident_memory_bytes gauge
apiserver的内存使用量(单位:Byte)

# HELP workqueue_adds_total [ALPHA] Total number of adds handled by workqueue
# TYPE workqueue_adds_total counter
apiserver中包含的controller的工作队列，已处理的任务总数

# HELP workqueue_depth [ALPHA] Current depth of workqueue
# TYPE workqueue_depth gauge
apiserver中包含的controller的工作队列深度，表示当前队列中要处理的任务的数量，数值越小越好 
例如APIServiceRegistrationController admission_quota_controller