Monitoring server

In production systems, monitoring of applications is crucial, and that includes databases as well. Memgraph allows monitoring the database via WebSocket server and a HTTP server.

Monitoring via WebSocket server

Connect to Memgraph's monitoring server via WebSocket to forwarded logs to all the connected clients.

Connection

To connect to Memgraph's WebSocket server use the following URL:

ws://host:port

The default host is localhost but it can be changed using the --monitoring-host configuration flag.
The default port is 7444 but it can be changed using the --monitoring-port configuration flag.

If you want to connect with a WebSocket Secure (WSS) connection. Set the following configuration flags to enable an SSL connection: --bolt-cert-file and --bolt-key-file.

These flags are also used to set up an SSL connection when connecting via Bolt protocol, hence the name.

If both of the configuration flags are set, use the following URL to connect to the WebSocket server:

wss://host:port

Authentication

If authentication is not used (there are no users present in Memgraph), no authentication message is expected, and no response will be returned.

If the authentication is used, Memgraph won't send a message to a certain connection until it's authenticated.

To authenticate, create a JSON with the credentials in the following format:

{
  "username": "<username>",
  "password": "<password>"
}

If the credentials are valid, the connection will be made, and the client will receive the messages. As a response, the client should receive the following message:

{
  "success": true,
  "message": "User has been successfully authenticated!"
}

If they are invalid or the first message is in the invalid format, the connection is dropped. As a response, the following message is sent:

{
  "success": false,
  "message": "<error-message>"
}

Authorization (Enterprise)

Permission for connecting through WebSocket is controlled by the WEBSOCKET privilege.

Log messages

Each log that is written to the log file is forwarded to the connected clients in the following format:

{
  event: "log",
  level: "trace"|"debug"|"info"|"warning"|"error"|"critical",
  message: "<log-message>"
}

Read more about logs in Memgraph.

Monitoring via HTTP server (Enterprise)

In the Enterprise Edition, Memgraph allows tracking information about transactions, query latencies, snapshot recovery latencies, triggers, bolt messages, indexes, streams, and many more using an HTTP server.

To start the metrics HTTP server, enter a valid Memgraph Enterprise license key and restart the database.

Configure the HTTP endpoint

The default address and port for the metrics server is 0.0.0.0:9091, and can be configured using the --metrics-address and --metrics-port configuration flags.

System metrics

All system metrics measuring different parts of the system can be divided into three different types:

• Gauge - a single value of some variable in the system (e.g. memory usage)
• Counter (uint64_t) - a value that can be incremented or decremented (e.g. number of active transactions in the system)
• Histogram (uint64_t) - distribution of measured values (e.g. certain percentile of query latency on N measured queries)

General metrics

Index metrics

Operator metrics

Before a Cypher query is executed, it is converted into an internal form suitable for execution, known as a query plan. A query plan is a tree-like data structure describing a pipeline of operations that will be performed on the database in order to yield the results for a given query. Every node within a plan is known as a logical operator and describes a particular operation.

Query metrics

Query type metrics

Session metrics

Snapshot metrics

Stream metrics

Transaction metrics

Trigger metrics

Example response

If there aren't any modifying configurations, by sending a GET request to localhost:9091 in the local Memgraph build will result in a response similar to the one below.

{
    "General": {
        "average_degree": 0.0,
        "disk_usage": 1417846,
        "edge_count": 0,
        "memory_usage": 36937728,
        "vertex_count": 0
    },
    "Index": {
        "ActiveLabelIndices": 0,
        "ActiveLabelPropertyIndices": 0
    },
    "Operator": {
        "AccumulateOperator": 0,
        "AggregateOperator": 0,
        "ApplyOperator": 0,
        "CallProcedureOperator": 0,
        "CartesianOperator": 0,
        "ConstructNamedPathOperator": 0,
        "CreateExpandOperator": 0,
        "CreateNodeOperator": 0,
        "DeleteOperator": 0,
        "DistinctOperator": 0,
        "EdgeUniquenessFilterOperator": 0,
        "EmptyResultOperator": 0,
        "EvaluatePatternFilterOperator": 0,
        "ExpandOperator": 0,
        "ExpandVariableOperator": 0,
        "FilterOperator": 0,
        "ForeachOperator": 0,
        "LimitOperator": 0,
        "MergeOperator": 0,
        "OnceOperator": 0,
        "OptionalOperator": 0,
        "OrderByOperator": 0,
        "ProduceOperator": 0,
        "RemoveLabelsOperator": 0,
        "RemovePropertyOperator": 0,
        "ScanAllByIdOperator": 0,
        "ScanAllByLabelOperator": 0,
        "ScanAllByLabelPropertyOperator": 0,
        "ScanAllByLabelPropertyRangeOperator": 0,
        "ScanAllByLabelPropertyValueOperator": 0,
        "ScanAllOperator": 0,
        "SetLabelsOperator": 0,
        "SetPropertiesOperator": 0,
        "SetPropertyOperator": 0,
        "SkipOperator": 0,
        "UnionOperator": 0,
        "UnwindOperator": 0
    },
    "Query": {
        "QueryExecutionLatency_us_50p": 0,
        "QueryExecutionLatency_us_90p": 0,
        "QueryExecutionLatency_us_99p": 0
    },
    "QueryType": {
        "ReadQuery": 0,
        "ReadWriteQuery": 0,
        "WriteQuery": 0
    },
    "Session": {
        "ActiveBoltSessions": 0,
        "ActiveSSLSessions": 0,
        "ActiveSessions": 0,
        "ActiveTCPSessions": 0,
        "ActiveWebSocketSessions": 0,
        "BoltMessages": 0
    },
    "Snapshot": {
        "SnapshotCreationLatency_us_50p": 4860,
        "SnapshotCreationLatency_us_90p": 4860,
        "SnapshotCreationLatency_us_99p": 4860,
        "SnapshotRecoveryLatency_us_50p": 628,
        "SnapshotRecoveryLatency_us_90p": 628,
        "SnapshotRecoveryLatency_us_99p": 628
    },
    "Stream": {
        "MessagesConsumed": 0,
        "StreamsCreated": 0
    },
    "Transaction": {
        "ActiveTransactions": 0,
        "CommitedTransactions": 0,
        "FailedQuery": 0,
        "RollbackedTransactions": 0
    },
    "Trigger": {
        "TriggersCreated": 0,
        "TriggersExecuted": 0
    }
}