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第3章 应用监控

应用监控说明​

prometheus的数据指标都是通过http实现的metrics接口获取到的，所以应用只需要暴露metrics接口，prometheus就可以定期的去拉取数据。

随着容器和k8s的流行，现在很多服务都自己内置了metrics接口，对于本身没有提供metrics的应用，promtheus官方也提供了很多可以直接使用的exporter来获取指标数据，比如redis_exporter,mysql_exporter等。

自带/metrics接口的应用检测​

k8s里的coredns自带的metrics接口，所以我们可以先拿来试试手，查看croedns的配置文件可以发现提供prometheus服务采集的端口是9153。

[root@node1 prom]# kubectl -n kube-system describe cm coredns
Name:         coredns
Namespace:    kube-system
Labels:       <none>
Annotations:  <none>

Data
====
Corefile:
----
.:53 {
    errors
    health {
       lameduck 5s
    }
    ready
    kubernetes cluster.local in-addr.arpa ip6.arpa {
       pods insecure
       fallthrough in-addr.arpa ip6.arpa
       ttl 30
    }
    prometheus :9153		#自带的prometheus监控暴露服务
    forward . /etc/resolv.conf {
       max_concurrent 1000
    }
    cache 30
    loop
    reload
    loadbalance
}

Events:  <none>

查看CoreDNS的Pod地址

[root@node1 prom]# kubectl -n kube-system get pod -l k8s-app=kube-dns -o wide
NAME                       READY   STATUS    RESTARTS   AGE   IP          NODE    NOMINATED NODE   READINESS GATES
coredns-6d56c8448f-ckwhg   1/1     Running   5          10d   10.2.0.17   node1   <none>           <none>
coredns-6d56c8448f-rvmdf   1/1     Running   5          10d   10.2.0.16   node1   <none>           <none>

直接访问/metrics接口

[root@node1 prom]# curl -I 10.2.0.17:9153/metrics
HTTP/1.1 200 OK
Content-Type: text/plain; version=0.0.4; charset=utf-8
Date: Wed, 11 Aug 2021 07:14:25 GMT

[root@node1 prom]# curl 10.2.0.17:9153/metrics

# HELP coredns_build_info A metric with a constant '1' value labeled by version, revision, and goversion from which CoreDNS was built.


# TYPE coredns_build_info gauge

coredns_build_info{goversion="go1.14.4",revision="f59c03d",version="1.7.0"} 1

# HELP coredns_cache_entries The number of elements in the cache.


# TYPE coredns_cache_entries gauge

coredns_cache_entries{server="dns://:53",type="denial"} 12
coredns_cache_entries{server="dns://:53",type="success"} 1

# HELP coredns_cache_misses_total The count of cache misses.


# TYPE coredns_cache_misses_total counter

coredns_cache_misses_total{server="dns://:53"} 13

# HELP coredns_dns_request_duration_seconds Histogram of the time (in seconds) each request took.


# TYPE coredns_dns_request_duration_seconds histogram

...........................................

知道了端口，也确认了可以访问，那么接下来我们就可以编辑prometheus的配置文件来发现这个服务了。

编辑prom-cm配置文件

[root@node1 prom]# cat prom-cm.yml
apiVersion: v1
kind: ConfigMap
metadata:
  name: prometheus-config
  namespace: prom
data:
  prometheus.yml: |
    global:
      scrape_interval: 15s
      scrape_timeout: 15s
    scrape_configs:
    - job_name: 'prometheus'
      static_configs:
      - targets: ['localhost:9090']

    - job_name: 'coredns'		#任务名称
      static_configs:				#静态配置
      - targets: ['10.2.0.16:9153','10.2.0.17:9153']		#这里我们直接写coredns的ClusterIP

更新prom-cm资源配置

[root@node1 prom]# kubectl apply -f prom-cm.yml

因为我们在prometheus的配置文件里配置了热更新的参数，所以可以不用重启pod在线热更新配置使其生效。

热更新promtheus配置

[root@node1 prom]# kubectl -n prom get pod -o wide
NAME                          READY   STATUS    RESTARTS   AGE   IP          NODE    NOMINATED NODE   READINESS GATES
prometheus-796566c67c-lhrns   1/1     Running   0          22m   10.2.2.86   node2   <none>           <none>

#注意要等一会，因为configmap更新到pod里需要点时间
[root@node1 prom]# curl -X POST "http://10.2.2.86:9090/-/reload"

查看promtheus发现

1726449159545-94a69056-bfaf-4802-ba5c-efe65fd3fcb5.png

使用exporter监控​

刚才我们说了，有些应用自带的metrics接口，那么对于没有自带metrics接口的应用，我们可以使用各种exporter监控，官方已经给我们提供了非常多的exporter,具体可以去官网查阅，地址如下：

https://prometheus.io/docs/instrumenting/exporters/

下面以mysql的exporter举例，具体的做法就是在每个mysql的pod里部署一个exporter服务来监控mysql的各项数据。

cat >mysql-prom.yaml <<EOF
apiVersion: apps/v1
kind: Deployment
metadata:
  name: mysql-dp
spec:
  replicas: 1
  selector:
    matchLabels:
      app: mysql
  template:
    metadata:
      labels:
        app: mysql
    spec:
      containers:
      - name: mysql
        image: mysql:5.7
        imagePullPolicy: IfNotPresent
        ports:
        - containerPort: 3306
        env:
        - name: MYSQL_ROOT_PASSWORD
          value: "123456"
      - name: mysql-exporter
        image: prom/mysqld-exporter
        imagePullPolicy: IfNotPresent
        ports:
        - containerPort: 9104
        env:
        - name: DATA_SOURCE_NAME
          value: "root:123456@(localhost:3306)/"
---
kind: Service
apiVersion: v1
metadata:
  name: mysql-svc
spec:
  selector:
    app: mysql
  ports:
  - name: mysql
    port: 3306
    targetPort: 3306
  - name: mysql-prom
    port: 9104
    targetPort: 9104
EOF

应用后查看

[root@node1 prom]# kubectl apply -f mysql-prom.yaml
deployment.apps/mysql-dp created
service/mysql-svc created

[root@node1 prom]# kubectl get pod
NAME                          READY   STATUS    RESTARTS   AGE
mysql-dp-79b48cff96-m96bz     2/2     Running   0          73s

[root@node1 prom]# kubectlget svc
NAME         TYPE        CLUSTER-IP    EXTERNAL-IP   PORT(S)             AGE
mysql-svc    ClusterIP   10.1.213.31   <none>        3306/TCP,9104/TCP   4m9s

修改prom配置文件,注意！因为prom和mysql在不同的命名空间，所以prom采集地址的时候需要使用service名称+命名空间

cat > prom-cm.yml << 'EOF'
apiVersion: v1
kind: ConfigMap
metadata:
  name: prometheus-config
  namespace: prom
data:
  prometheus.yml: |
    global:
      scrape_interval: 15s
      scrape_timeout: 15s
    scrape_configs:
    - job_name: 'prometheus'
      static_configs:
      - targets: ['localhost:9090']

    - job_name: 'coredns'
      static_configs:
      - targets: ['10.2.0.16:9153','10.2.0.17:9153']

    - job_name: 'mysql'
      static_configs:
      - targets: ['mysql-svc.default:9104']
EOF

更新配置

[root@node1 prom]# kubectl apply -f prom-cm.yml
configmap/prometheus-config configured

[root@node1 prom]# curl -X POST "http://10.2.2.86:9090/-/reload"

查看promtheus

更新: 2024-09-21 15:52:29

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