Kubernetes 中大量用到了证书, 比如 ca证书、以及 kubelet、apiserver、proxy、etcd等组件,还有 kubeconfig 文件。
如果证书过期,轻则无法登录 Kubernetes 集群,重则整个集群异常。
为了解决证书过期的问题,一般有以下几种方式:
本次主要介绍关于 Kubernetes 集群证书过期的监控,这里提供 3 种监控方案:
/etc/kubernetes/pki
和 /var/lib/kubelet
下的证书以及 kubeconfig 文件Blackbox Exporter 用于探测 HTTPS、HTTP、TCP、DNS、ICMP 和 grpc 等 Endpoint。在你定义 Endpoint 后,Blackbox Exporter 会生成指标,可以使用 Grafana 等工具进行可视化。Blackbox Exporter 最重要的功能之一是测量 Endpoint 的可用性。
当然, Blackbox Exporter 探测 HTTPS 后就可以获取到证书的相关信息, 就是利用这种方式实现对 Kubernetes apiserver 证书过期时间的监控.
调整 Blackbox Exporter 的配置, 增加 insecure_tls_verify: true
, 如下:
重启 blackbox exporter: kubectl rollout restart deploy ...
增加对 Kubernetes APIServer 内部端点https://kubernetes.default.svc.cluster.local/readyz的监控.
如果你没有使用 Prometheus Operator, 使用的是原生的 Prometheus, 则需要修改 Prometheus 配置文件的 configmap 或 secret, 添加 scrape config, 示例如下:
如果在使用 Prometheus Operator, 则可以增加如下 Probe CRD, Prometheus Operator 会自动将其转换并 merge 到 Prometheus 中.
apiVersion: monitoring.coreos.com/v1
kind: Probe
metadata:
name: kubernetes-apiserver
spec:
interval: 60s
module: http_2xx
prober:
path: /probe
url: monitor-prometheus-blackbox-exporter.default.svc.cluster.local:9115
targets:
staticConfig:
static:
- https://kubernetes.default.svc.cluster.local/readyz
最后, 可以增加 Prometheus 告警 Rule, 这里就直接用 Prometheus Operator 创建 PrometheusRule CRD 做示例了, 示例如下:
apiVersion: monitoring.coreos.com/v1
kind: PrometheusRule
metadata:
name: prometheus-blackbox-exporter
spec:
groups:
- name: prometheus-blackbox-exporter
rules:
- alert: BlackboxSslCertificateWillExpireSoon
expr: probe_ssl_earliest_cert_expiry - time() < 86400 * 30
for: 0m
labels:
severity: warning
- alert: BlackboxSslCertificateWillExpireSoon
expr: probe_ssl_earliest_cert_expiry - time() < 86400 * 14
for: 0m
labels:
severity: critical
- alert: BlackboxSslCertificateExpired
annotations:
description: |-
SSL certificate has expired already
VALUE = {{ $value }}
LABELS = {{ $labels }}
summary: SSL certificate expired (instance {{ $labels.instance }})
expr: probe_ssl_earliest_cert_expiry - time() <= 0
for: 0m
labels:
severity: emergency
这里可以参考我的文章:Prometheus Operator 与 kube-prometheus 之二 - 如何监控 1.23+ kubeadm 集群, 安装完成后, 开箱即用.
开箱即用内容包括:
这里用到的指标有:
apiserver_client_certificate_expiration_seconds_count
apiserver_client_certificate_expiration_seconds_bucket
kubelet_certificate_manager_client_expiration_renew_errors
kubelet_server_expiration_renew_errors
kubelet_certificate_manager_client_ttl_seconds
kubelet_certificate_manager_server_ttl_seconds
对应的 Prometheus 告警规则如下:
该 Exporter 是通过监控集群所有node的指定目录或 path 下的证书文件以及 kubeconfig 文件来获取证书信息.
如果是使用 kubeadm 搭建的 Kubernetes 集群, 则可以监控如下包含证书的文件和 kubeconfig:
watchFiles:
- /var/lib/kubelet/pki/kubelet-client-current.pem
- /etc/kubernetes/pki/apiserver.crt
- /etc/kubernetes/pki/apiserver-etcd-client.crt
- /etc/kubernetes/pki/apiserver-kubelet-client.crt
- /etc/kubernetes/pki/ca.crt
- /etc/kubernetes/pki/front-proxy-ca.crt
- /etc/kubernetes/pki/front-proxy-client.crt
- /etc/kubernetes/pki/etcd/ca.crt
- /etc/kubernetes/pki/etcd/healthcheck-client.crt
- /etc/kubernetes/pki/etcd/peer.crt
- /etc/kubernetes/pki/etcd/server.crt
watchKubeconfFiles:
- /etc/kubernetes/admin.conf
- /etc/kubernetes/controller-manager.conf
- /etc/kubernetes/scheduler.conf
编辑 values.yaml:
kubeVersion: ''
extraLabels: {}
nameOverride: ''
fullnameOverride: ''
imagePullSecrets: []
image:
registry: docker.io
repository: enix/x509-certificate-exporter
tag:
pullPolicy: IfNotPresent
psp:
create: false
rbac:
create: true
secretsExporter:
serviceAccountName:
serviceAccountAnnotations: {}
clusterRoleAnnotations: {}
clusterRoleBindingAnnotations: {}
hostPathsExporter:
serviceAccountName:
serviceAccountAnnotations: {}
clusterRoleAnnotations: {}
clusterRoleBindingAnnotations: {}
podExtraLabels: {}
podAnnotations: {}
exposePerCertificateErrorMetrics: false
exposeRelativeMetrics: false
metricLabelsFilterList: null
secretsExporter:
enabled: true
debugMode: false
replicas: 1
restartPolicy: Always
strategy: {}
resources:
limits:
cpu: 200m
memory: 150Mi
requests:
cpu: 20m
memory: 20Mi
nodeSelector: {}
tolerations: []
affinity: {}
podExtraLabels: {}
podAnnotations: {}
podSecurityContext: {}
securityContext:
runAsUser: 65534
runAsGroup: 65534
readOnlyRootFilesystem: true
capabilities:
drop:
- ALL
secretTypes:
- type: kubernetes.io/tls
key: tls.crt
includeNamespaces: []
excludeNamespaces: []
includeLabels: []
excludeLabels: []
cache:
enabled: true
maxDuration: 300
hostPathsExporter:
debugMode: false
restartPolicy: Always
updateStrategy: {}
resources:
limits:
cpu: 100m
memory: 40Mi
requests:
cpu: 10m
memory: 20Mi
nodeSelector: {}
tolerations: []
affinity: {}
podExtraLabels: {}
podAnnotations: {}
podSecurityContext: {}
securityContext:
runAsUser: 0
runAsGroup: 0
readOnlyRootFilesystem: true
capabilities:
drop:
- ALL
watchDirectories: []
watchFiles: []
watchKubeconfFiles: []
daemonSets:
cp:
nodeSelector:
node-role.kubernetes.io/master: ''
tolerations:
- effect: NoSchedule
key: node-role.kubernetes.io/master
operator: Exists
watchFiles:
- /var/lib/kubelet/pki/kubelet-client-current.pem
- /etc/kubernetes/pki/apiserver.crt
- /etc/kubernetes/pki/apiserver-etcd-client.crt
- /etc/kubernetes/pki/apiserver-kubelet-client.crt
- /etc/kubernetes/pki/ca.crt
- /etc/kubernetes/pki/front-proxy-ca.crt
- /etc/kubernetes/pki/front-proxy-client.crt
- /etc/kubernetes/pki/etcd/ca.crt
- /etc/kubernetes/pki/etcd/healthcheck-client.crt
- /etc/kubernetes/pki/etcd/peer.crt
- /etc/kubernetes/pki/etcd/server.crt
watchKubeconfFiles:
- /etc/kubernetes/admin.conf
- /etc/kubernetes/controller-manager.conf
- /etc/kubernetes/scheduler.conf
nodes:
watchFiles:
- /var/lib/kubelet/pki/kubelet-client-current.pem
- /etc/kubernetes/pki/ca.crt
rbacProxy:
enabled: false
podListenPort: 9793
hostNetwork: false
service:
create: true
port: 9793
annotations: {}
extraLabels: {}
prometheusServiceMonitor:
create: true
scrapeInterval: 60s
scrapeTimeout: 30s
extraLabels: {}
relabelings: {}
prometheusPodMonitor:
create: false
prometheusRules:
create: true
alertOnReadErrors: true
readErrorsSeverity: warning
alertOnCertificateErrors: true
certificateErrorsSeverity: warning
certificateRenewalsSeverity: warning
certificateExpirationsSeverity: critical
warningDaysLeft: 30
criticalDaysLeft: 14
extraLabels: {}
alertExtraLabels: {}
rulePrefix: ''
disableBuiltinAlertGroup: false
extraAlertGroups: []
extraDeploy: []
通过 Helm Chart 安装:
helm repo add enix https://charts.enix.io
helm install x509-certificate-exporter enix/x509-certificate-exporter
通过这个 Helm Chart 也会自动安装:
其监控指标为:
x509_cert_not_after
该 Exporter 还提供了一个比较花哨的 Grafana Dashboard, 如下:
Alert Rules 如下:
为了监控 Kubernetes 集群的证书过期时间, 我们提供了 3 种方案, 各有优劣:
/etc/kubernetes/pki
和 /var/lib/kubelet
下的证书以及 kubeconfig 文件
可以根据您的实际情况灵活进行选择.
🎉🎉🎉
三人行, 必有我师; 知识共享, 天下为公. 本文由东风微鸣技术博客 EWhisper.cn 编写.