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Health Check

Health Check provides ping() and diagnostics() tests for the health of the network and the cluster.

Ping and diagnostics methods, on the bucket and cluster objects respectively, can give us information about the current state of nodes, and their connections.

Uses

'Ping` provides a raw JSON payload suitable for feeding into reactive log and aggregation components, including monitoring systems like Splunk, ElasticSearch, and Nagios. It can also help keep connections alive if you are operating across an environment which aggressively closes down unused connections.

Diagnostics provides a strongly typed API for proactive, pull-based monitoring systems, such as:

This API does not provide binary yes/no answers about the health of the cluster; rather it summarizes as much information as possible, for the application developer to assemble a complete, contextual view and come to a conclusion.

Note: Ping may reopen a connection, so is not without side-effects. Diagnostics shows what the SDK perceives as the current state of the network and services — it is without side-effects, but may not be up to date.

Ping

Ping actively queries the status of the specified services,giving status and latency information for every node reachable. In addition to its use as a monitoring tool, a regular Ping can be used in an environment which does not respect keep alive values for a connection. This is a Map (a JavaScript object) with type keys for each service available, such as kv and n1ql, and the value containing latency and status information.

let services = [couchbase.ServiceType.KeyValue, couchbase.ServiceType.Query]
bucket.ping(services, (err, res) => {
    console.log(res)
})
/*
{
    "config_rev":1822,
    "id":"0x102f09dc0",
    "sdk":"libcouchbase/2.9.5-njs couchnode/2.6.9 (node/10.16.0; v8/6.8.275.32-node.52; ssl/1.1.1b)",
    "services":{
        "kv":[
            {
                "id":"0x104802900",
                "latency_us":1542,
                "local":"10.112.195.1:51707",
                "remote":"10.112.195.101:11210",
                "scope":"travel-sample",
                "status":"ok"
            },
            {
                "id":"0x1029253d0",
                "latency_us":6639,
                "local":"10.112.195.1:51714",
                "remote":"10.112.195.103:11210",
                "scope":"travel-sample",
                "status":"ok"
            },
            {
                "id":"0x102924bc0",
                "latency_us":1240660,
                "local":"10.112.195.1:51713",
                "remote":"10.112.195.102:11210",
                "scope":"travel-sample",
                "status":"timeout"
            }
        ],
        "n1ql":[
            {
                "id":"0x10291d980",
                "latency_us":3787,
                "local":"10.112.195.1:51710",
                "remote":"10.112.195.101:8093",
                "status":"ok"
            },
            {
                "id":"0x1029240f0",
                "latency_us":9321,
                "local":"10.112.195.1:51712",
                "remote":"10.112.195.103:8093",
                "status":"ok"
            },
            {
                "id":"0x102923350",
                "latency_us":7003363,
                "local":"10.112.195.1:51711",
                "remote":"10.112.195.102:8093",
                "status":"timeout"
            }
        ]
    },
    "version":1
}
*/

Diagnostics

Diagnostics returns a list of the nodes that the SDK currently has (or had) a connection to, and the current status of the connection. However this call does not actively poll the nodes, reporting instead the state the last time it tried to access each node. If you want the current status, then use Ping.

bucket.diagnostics((err, res) => {
    console.log(res)
})
/*
{
    "id":"0x10290d100","kv":[
        {
            "id":"0000000072b21d66",
            "last_activity_us":2363294,
            "local":"10.112.195.1:51473",
            "remote":"10.112.195.101:11210",
            "status":"connected"
        },
        {
            "id":"000000000ba84e5e",
            "last_activity_us":7369021,
            "local":"10.112.195.1:51486",
            "remote":"10.112.195.102:11210",
            "status":"connected"
        },
        {
            "id":"0000000077689398",
            "last_activity_us":4855640,
            "local":"10.112.195.1:51409",
            "remote":"10.112.195.103:11210",
            "status":"connected"
        }
    ],
    "sdk":"libcouchbase/2.9.5-njs couchnode/2.6.9 (node/10.16.0; v8/6.8.275.32-node.52; ssl/1.1.1b)",
    "version":1
}
*/