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Monitoring Nodes

  • This tutorial describes the important metrics and how to monitor them for each node in the cluster
  • Learn how to run GET requests for node-level metrics and see several example requests

GET Nodes Overview

We can GET Nodes according to the documentation for Couchbase REST Node Overview using:

http://localhost:8091/pools/nodes

Response

{
  "nodes": [
    {
      "hostname": "10.112.170.101:8091",
      "thisNode": true,
      "ports": {
        "sslProxy": 11214,
        "httpsMgmt": 18091,
        "httpsCAPI": 18092,
        "proxy": 11211,
        "direct": 11210
      },
      "services": ["fts", "index", "kv", "n1ql", "cbas", "eventing"]
    }
  ]
}

Each node in the cluster is listed in the "nodes" array. The thisNode attribute indicates the node you have executed the query against. Using this output, a monitoring agent can discover new nodes within the cluster and which services are assigned to those nodes in order to automatically apply the correct monitoring profile.

Key Metrics to Monitor

Couchbase Metric Description Response
status This is a meta metric that indicates overall node health. Alert if the value is "unhealthy".
clusterMembership Indicates whether the node is an active participant in cluster operations. Possible values are "active", "inactiveAdded", and "inactiveFailed". Alert on "inactiveFailed" and investigate the cause of the node failure.

Example

This example illustrates retrieving the status of each node in the cluster.

curl \
  --user Administrator:password \
  --silent \
	--request GET \
  http://localhost:8091/pools/nodes | \
  jq -r '.nodes[] | .hostname + " (" +.status + ")"'

Example

The following example displays the cluster membership of each node.

curl \
  --user Administrator:password \
  --silent \
	--request GET \
  http://localhost:8091/pools/nodes | \
  jq -r '.nodes[] | .hostname + " (" +.clusterMembership + ")"'

Example

Show the services and system stats for each node in the cluster.

curl \
  --user Administrator:password \
  --silent \
	--request GET \
  http://localhost:8091/pools/nodes | \
  jq -r '.nodes[] | .hostname + " (" + (.services | join(", ")) + ")\n" +
  "  cpu_utilization_rate: " +
    ( .systemStats.cpu_utilization_rate | tostring) + "%\n" +
  "  swap_total: " +
    ( .systemStats.swap_total / 1024 / 1024 | tostring) + "MB\n" +
  "  swap_used: " +
    ( .systemStats.swap_used / 1024 / 1024 | tostring) + "MB (" +
    ( (.systemStats.swap_used / .systemStats.swap_total) * 100 | tostring) + "%)\n" +
  "  mem_total: " +
    ( .systemStats.mem_total / 1024 / 1024 | tostring) + "MB\n" +
  "  mem_free: " +
    ( .systemStats.mem_free / 1024 / 1024 | tostring) + "MB (" +
    ( (.systemStats.mem_free / .systemStats.mem_total) * 100 | tostring) + "%)"
   '
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