Alert manager is not triggering any alerts

Question

There are alerts in Prometheus but slack firing is not happening . Alertmanager says no alerts. i'm attaching the config files of alertmanager and prometheus rules.

Need some immediate help as this is a production related issue. prometheus-rules.yaml

apiVersion: v1
kind: ConfigMap
metadata:
  creationTimestamp: null
  name: prometheus-rules-conf
  namespace: monitoring
data:
  kubernetes_alerts.yml: |
    groups:
      - name: kubernetes_alerts
        rules:
        - alert: DeploymentGenerationOff
          expr: kube_deployment_status_observed_generation != kube_deployment_metadata_generation
          for: 5m
          labels:
            severity: warning
          annotations:
            description: Deployment generation does not match expected generation {{ $labels.namespace }}/{{ $labels.deployment }}
            summary: Deployment is outdated
        - alert: DeploymentReplicasNotUpdated
          expr: ((kube_deployment_status_replicas_updated != kube_deployment_spec_replicas)
            or (kube_deployment_status_replicas_available != kube_deployment_spec_replicas))
            unless (kube_deployment_spec_paused == 1)
          for: 5m
          labels:
            severity: warning
          annotations:
            description: Replicas are not updated and available for deployment {{ $labels.namespace }}/{{ $labels.deployment }}
            summary: Deployment replicas are outdated
        - alert: PodzFrequentlyRestarting
          expr: increase(kube_pod_container_status_restarts_total[1h]) > 5
          for: 10m
          labels:
            severity: warning
          annotations:
            description: Pod {{ $labels.namespace }}/{{ $labels.pod }} was restarted {{ $value }} times within the last hour
            summary: Pod is restarting frequently
        - alert: KubeNodeNotReady
          expr: kube_node_status_condition{condition="Ready",status="true"} == 0
          for: 1h
          labels:
            severity: warning
          annotations:
            description: The Kubelet on {{ $labels.node }} has not checked in with the API,
              or has set itself to NotReady, for more than an hour
            summary: Node status is NotReady
        - alert: KubeManyNodezNotReady
          expr: count(kube_node_status_condition{condition="Ready",status="true"} == 0)
            > 1 and (count(kube_node_status_condition{condition="Ready",status="true"} ==
            0) / count(kube_node_status_condition{condition="Ready",status="true"})) > 0.2
          for: 1m
          labels:
            severity: critical
          annotations:
            description: '{{ $value }}% of Kubernetes nodes are not ready'
        - alert: APIHighLatency
          expr: apiserver_latency_seconds:quantile{quantile="0.99",subresource!="log",verb!~"^(?:WATCH|WATCHLIST|PROXY|CONNECT)$"} > 4
          for: 10m
          labels:
            severity: critical
          annotations:
            description: the API server has a 99th percentile latency of {{ $value }} seconds for {{ $labels.verb }} {{ $labels.resource }}
        - alert: APIServerErrorsHigh
          expr: rate(apiserver_request_count{code=~"^(?:5..)$"}[5m]) / rate(apiserver_request_count[5m]) * 100 > 5
          for: 10m
          labels:
            severity: critical
          annotations:
            description: API server returns errors for {{ $value }}% of requests
        - alert: KubernetesAPIServerDown
          expr: up{job="kubernetes-apiservers"} == 0
          for: 10m
          labels:
            severity: critical
          annotations:
            summary: Apiserver {{ $labels.instance }} is down!
        - alert: KubernetesAPIServersGone
          expr:  absent(up{job="kubernetes-apiservers"})
          for: 10m
          labels:
            severity: critical
          annotations:
            summary: No Kubernetes apiservers are reporting!
            description: Werner Heisenberg says - OMG Where are my apiserverz?
  prometheus_alerts.yml: |
    groups:
    - name: prometheus_alerts
      rules:
      - alert: PrometheusConfigReloadFailed
        expr: prometheus_config_last_reload_successful == 0
        for: 10m
        labels:
          severity: warning
        annotations:
          description: Reloading Prometheus configuration has failed on {{$labels.instance}}.
      - alert: PrometheusNotConnectedToAlertmanagers
        expr: prometheus_notifications_alertmanagers_discovered < 1
        for: 1m
        labels:
          severity: warning
        annotations:
          description: Prometheus {{ $labels.instance}} is not connected to any Alertmanagers
  node_alerts.yml: |
    groups:
    - name: node_alerts
      rules:
      - alert: HighNodeCPU
        expr: instance:node_cpu:avg_rate5m > 80
        for: 10s
        labels:
          severity: warning
        annotations:
          summary: High Node CPU of {{ humanize $value}}% for 1 hour
      - alert: DiskWillFillIn4Hours
        expr: predict_linear(node_filesystem_free_bytes{mountpoint="/"}[1h], 4*3600) < 0
        for: 5m
        labels:
          severity: critical
        annotations:
          summary: Disk on {{ $labels.instance }} will fill in approximately 4 hours.
      - alert: KubernetesServiceDown
        expr: up{job="kubernetes-service-endpoints"} == 0
        for: 10m
        labels:
          severity: critical
        annotations:
          summary: Pod {{ $labels.instance }} is down!
      - alert: KubernetesServicesGone
        expr:  absent(up{job="kubernetes-service-endpoints"})
        for: 10m
        labels:
          severity: critical
        annotations:
          summary: No Kubernetes services are reporting!
          description: Werner Heisenberg says - OMG Where are my servicez?
      - alert: CriticalServiceDown
        expr: node_systemd_unit_state{state="active"} != 1
        for: 2m
        labels:
          severity: critical
        annotations:
          summary: Service {{ $labels.name }} failed to start.
          description: Service {{ $labels.instance }} failed to (re)start service {{ $labels.name }}.
  proxy_alert.yml: |
    groups:
    - name: proxy_alert
      rules:
      - alert: Proxy_Down
        expr: probe_success{instance="http://ip",job="blackbox"} == 0
        for: 5m
        labels:
          severity: critical
        annotations:
          summary: Proxy Server {{ $labels.instance }} is down!
      kubernetes_rules.yml: |
    groups:
      - name: kubernetes_rules
        rules:
        - record: apiserver_latency_seconds:quantile
          expr: histogram_quantile(0.99, rate(apiserver_request_latencies_bucket[5m])) / 1e+06
          labels:
            quantile: "0.99"
        - record: apiserver_latency_seconds:quantile
          expr: histogram_quantile(0.9, rate(apiserver_request_latencies_bucket[5m])) / 1e+06
          labels:
            quantile: "0.9"
        - record: apiserver_latency_seconds:quantile
          expr: histogram_quantile(0.5, rate(apiserver_request_latencies_bucket[5m])) / 1e+06
          labels:
            quantile: "0.5"

prometheus - configmap yaml

alerting:
      alertmanagers:
      - kubernetes_sd_configs:
        - role: endpoints
        relabel_configs:
        - source_labels: [__meta_kubernetes_service_name]
          regex: alertmanager
          action: keep
        - source_labels: [__meta_kubernetes_namespace]
          regex: monitoring
          action: keep
        - source_labels: [__meta_kubernetes_pod_container_port_number]
          action: keep
          regex: 9093
rule_files:
      - "/var/prometheus/rules/*_rules.yml"
      - "/var/prometheus/rules/*_alerts.yml"

Even though im getting endpoint in prometheus, alert is still not getting triggerd.

Answer 1

The problem: you've set an alert on prometheus ,but it doesn't trigger an event. I've gathered few Rules of thumb for verifying your alert is set properly, updated and works on prometheus dashboard like a charm:

1. Make sure your code is updated and deployed in your ec2 machine (quick glance in your source code)
2. Verify you yml file written in correct identation
3. Your new alert file is targeted on prometheus.yml on rule_files key and in the right internal path.
4. Make sure AlertManager service restarted in docker & Prometheus scraper is reloaded properly (verify in logs).

(To do so use)

docker restart <alert-manager-service-name>
curl -X POST localhost:9090/-/reload 

5. Locate your new alert on localhost:9090/alerts and verify that the condition statement is valid and should trigger an event (event -> route -> receiver).
6. The receiver should connect third party service with correct and valid authentication token (for slack / pager duty / jira etc...)