Health Check

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

Working in distributed environments is hard. Latencies come and go, so do connections in their entirety. Is it a network glitch, or is the remote cluster down? Sometimes just knowing the likely cause is enough to get a good start on a workaround, or at least avoid hours wasted on an inappropriate solution.

Health Check enables useful diagnostics on the state of Couchbase Clusters across networks. Ping and diagnostics methods on the bucket and cluster objects respectively, can give us information about the current state of nodes, and their connections.

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
}
*/