local-test-zookeeper-delta-02/afc-zookeeper/zookeeper-docs/src/main/resources/markdown/zookeeperMonitor.md

ZooKeeper Monitor Guide

• New Metrics System

  • Metrics
  • Prometheus
  • Alerting with Prometheus
  • Grafana
  • InfluxDB

• JMX

• Four letter words

New Metrics System

The feature:New Metrics System has been available since 3.6.0 which provides the abundant metrics to help users monitor the ZooKeeper on the topic: znode, network, disk, quorum, leader election, client, security, failures, watch/session, requestProcessor, and so forth.

Metrics

All the metrics are included in the ServerMetrics.java.

Pre-requisites:

• Enable the Prometheus MetricsProvider by setting the following in zoo.cfg:

  metricsProvider.className=org.apache.zookeeper.metrics.prometheus.PrometheusMetricsProvider
  

• The port for Prometheus metrics can be configured using:

  metricsProvider.httpPort=7000  # Default port is 7000
  

Enabling HTTPS for Prometheus Metrics:

ZooKeeper also supports SSL for Prometheus metrics, which provides secure data transmission. To enable this, configure an HTTPS port and set up SSL certificates as follows:

• Define the HTTPS port:

  metricsProvider.httpsPort=4443
  

• Configure the SSL key store (holds the server’s private key and certificates):

  metricsProvider.ssl.keyStore.location=/path/to/keystore.jks
  metricsProvider.ssl.keyStore.password=your_keystore_password
  metricsProvider.ssl.keyStore.type=jks  # Default is JKS
  

• Configure the SSL trust store (used to verify client certificates):

  metricsProvider.ssl.trustStore.location=/path/to/truststore.jks
  metricsProvider.ssl.trustStore.password=your_truststore_password
  metricsProvider.ssl.trustStore.type=jks  # Default is JKS
  

• Note: You can enable both HTTP and HTTPS simultaneously by defining both ports:

  metricsProvider.httpPort=7000
  metricsProvider.httpsPort=4443
  

Prometheus

• Running a Prometheus monitoring service is the easiest way to ingest and record ZooKeeper's metrics.

• Install Prometheus: Go to the official website download page, download the latest release.

• Set Prometheus's scraper to target the ZooKeeper cluster endpoints:

  cat > /tmp/test-zk.yaml <<EOF
  global:
    scrape_interval: 10s
  scrape_configs:
    - job_name: test-zk
      static_configs:
      - targets: ['192.168.10.32:7000','192.168.10.33:7000','192.168.10.34:7000']
  EOF
  cat /tmp/test-zk.yaml
  

• Set up the Prometheus handler:

  nohup /tmp/prometheus \
      --config.file /tmp/test-zk.yaml \
      --web.listen-address ":9090" \
      --storage.tsdb.path "/tmp/test-zk.data" >> /tmp/test-zk.log  2>&1 &
  

• Now Prometheus will scrape zk metrics every 10 seconds.

Alerting with Prometheus

• We recommend that you read Prometheus Official Alerting Page to explore some principles of alerting

• We recommend that you use Prometheus Alertmanager which can help users to receive alerting email or instant message(by webhook) in a more convenient way

• We provide an alerting example where these metrics should be taken a special attention. Note: this is for your reference only, and you need to adjust them according to your actual situation and resource environment

    use ./promtool check rules rules/zk.yml to check the correctness of the config file
    cat rules/zk.yml
  
    groups:
    - name: zk-alert-example
      rules:
      - alert: ZooKeeper server is down
        expr:  up == 0
        for: 1m
        labels:
          severity: critical
        annotations:
          summary: "Instance {{ $labels.instance }} ZooKeeper server is down"
          description: "{{ $labels.instance }} of job {{$labels.job}} ZooKeeper server is down: [{{ $value }}]."
  
      - alert: create too many znodes
        expr: znode_count > 1000000
        for: 1m
        labels:
          severity: warning
        annotations:
          summary: "Instance {{ $labels.instance }} create too many znodes"
          description: "{{ $labels.instance }} of job {{$labels.job}} create too many znodes: [{{ $value }}]."
  
      - alert: create too many connections
        expr: num_alive_connections > 50 # suppose we use the default maxClientCnxns: 60
        for: 1m
        labels:
          severity: warning
        annotations:
          summary: "Instance {{ $labels.instance }} create too many connections"
          description: "{{ $labels.instance }} of job {{$labels.job}} create too many connections: [{{ $value }}]."
  
      - alert: znode total occupied memory is too big
        expr: approximate_data_size /1024 /1024 > 1 * 1024 # more than 1024 MB(1 GB)
        for: 1m
        labels:
          severity: warning
        annotations:
          summary: "Instance {{ $labels.instance }} znode total occupied memory is too big"
          description: "{{ $labels.instance }} of job {{$labels.job}} znode total occupied memory is too big: [{{ $value }}] MB."
  
      - alert: set too many watch
        expr: watch_count > 10000
        for: 1m
        labels:
          severity: warning
        annotations:
          summary: "Instance {{ $labels.instance }} set too many watch"
          description: "{{ $labels.instance }} of job {{$labels.job}} set too many watch: [{{ $value }}]."
  
      - alert: a leader election happens
        expr: increase(election_time_count[5m]) > 0
        for: 1m
        labels:
          severity: warning
        annotations:
          summary: "Instance {{ $labels.instance }} a leader election happens"
          description: "{{ $labels.instance }} of job {{$labels.job}} a leader election happens: [{{ $value }}]."
  
      - alert: open too many files
        expr: open_file_descriptor_count > 300
        for: 1m
        labels:
          severity: warning
        annotations:
          summary: "Instance {{ $labels.instance }} open too many files"
          description: "{{ $labels.instance }} of job {{$labels.job}} open too many files: [{{ $value }}]."
  
      - alert: fsync time is too long
        expr: rate(fsynctime_sum[1m]) > 100
        for: 1m
        labels:
          severity: warning
        annotations:
          summary: "Instance {{ $labels.instance }} fsync time is too long"
          description: "{{ $labels.instance }} of job {{$labels.job}} fsync time is too long: [{{ $value }}]."
  
      - alert: take snapshot time is too long
        expr: rate(snapshottime_sum[5m]) > 100
        for: 1m
        labels:
          severity: warning
        annotations:
          summary: "Instance {{ $labels.instance }} take snapshot time is too long"
          description: "{{ $labels.instance }} of job {{$labels.job}} take snapshot time is too long: [{{ $value }}]."
  
      - alert: avg latency is too high
        expr: avg_latency > 100
        for: 1m
        labels:
          severity: warning
        annotations:
          summary: "Instance {{ $labels.instance }} avg latency is too high"
          description: "{{ $labels.instance }} of job {{$labels.job}} avg latency is too high: [{{ $value }}]."
  
      - alert: JvmMemoryFillingUp
        expr: jvm_memory_bytes_used / jvm_memory_bytes_max{area="heap"} > 0.8
        for: 5m
        labels:
          severity: warning
        annotations:
          summary: "JVM memory filling up (instance {{ $labels.instance }})"
          description: "JVM memory is filling up (> 80%)\n labels: {{ $labels }}  value = {{ $value }}\n"
  

Grafana

• Grafana has built-in Prometheus support; just add a Prometheus data source:

  Name:   test-zk
  Type:   Prometheus
  Url:    http://localhost:9090
  Access: proxy
  

• Then download and import the default ZooKeeper dashboard template and customize.

• Users can ask for Grafana dashboard account if having any good improvements by writing a email to dev@zookeeper.apache.org.

InfluxDB

InfluxDB is an open source time series data that is often used to store metrics from Zookeeper. You can download the open source version or create a free account on InfluxDB Cloud. In either case, configure the Apache Zookeeper Telegraf plugin to start collecting and storing metrics from your Zookeeper clusters into your InfluxDB instance. There is also an Apache Zookeeper InfluxDB template that includes the Telegraf configurations and a dashboard to get you set up right away.

JMX

More details can be found in here

Four letter words

More details can be found in here