监控

Monitoring NATS

To monitor the NATS messaging system, nats-server provides a lightweight HTTP server on a dedicated monitoring port. The monitoring server provides several endpoints, providing statistics and other information about the following:

• General Server Information

• Connections

• Routing

• Leaf Nodes

• Subscription Routing

• Account Information

• Account Stats

• JetStream Information

• Health

All endpoints return a JSON object.

The NATS monitoring endpoints support JSONP and CORS, making it easy to create single page monitoring web applications. Part of the NATS ecosystem is a tool called nats-top that visualizes data from these endpoints on the command line.

nats-server does not have authentication/authorization for the monitoring endpoint. When you plan to open your nats-server to the internet make sure to not expose the monitoring port as well. By default, monitoring binds to every interface 0.0.0.0 so consider setting monitoring to localhost or have appropriate firewall rules.

Enabling monitoring

Monitoring can be enabled in server configuration or as a server command-line option. The conventional port is 8222.

As server configuration:

http_port: 8222

As a command-line option:

nats-server -m 8222

Once the server is running using one of the two methods, go to http://localhost:8222 to browse the available endpoints detailed below.

Monitoring Endpoints

General Information

The /varz endpoint returns general information about the server state and configuration.

Result	Return Code
Success	200 (OK)
Error	400 (Bad Request)

Arguments

N/A

Example

https://demo.nats.io:8222/varz

Response

{
  "server_id": "NACDVKFBUW4C4XA24OOT6L4MDP56MW76J5RJDFXG7HLABSB46DCMWCOW",
  "version": "2.0.0",
  "proto": 1,
  "go": "go1.12",
  "host": "0.0.0.0",
  "port": 4222,
  "max_connections": 65536,
  "ping_interval": 120000000000,
  "ping_max": 2,
  "http_host": "0.0.0.0",
  "http_port": 8222,
  "https_port": 0,
  "auth_timeout": 1,
  "max_control_line": 4096,
  "max_payload": 1048576,
  "max_pending": 67108864,
  "cluster": {},
  "gateway": {},
  "leaf": {},
  "tls_timeout": 0.5,
  "write_deadline": 2000000000,
  "start": "2019-06-24T14:24:43.928582-07:00",
  "now": "2019-06-24T14:24:46.894852-07:00",
  "uptime": "2s",
  "mem": 9617408,
  "cores": 4,
  "gomaxprocs": 4,
  "cpu": 0,
  "connections": 0,
  "total_connections": 0,
  "routes": 0,
  "remotes": 0,
  "leafnodes": 0,
  "in_msgs": 0,
  "out_msgs": 0,
  "in_bytes": 0,
  "out_bytes": 0,
  "slow_consumers": 0,
  "subscriptions": 0,
  "http_req_stats": {
    "/": 0,
    "/connz": 0,
    "/gatewayz": 0,
    "/routez": 0,
    "/subsz": 0,
    "/varz": 1
  },
  "config_load_time": "2019-06-24T14:24:43.928582-07:00"
}

Connection Information

The /connz endpoint reports more detailed information on current and recently closed connections. It uses a paging mechanism which defaults to 1024 connections.

Result	Return Code
Success	200 (OK)
Error	400 (Bad Request)

Arguments

Argument	Values	Description
sort	(see sort options)	Sorts the results. Default is connection ID.
auth	true, 1, false, 0	Include username. Default is false.
subs	true, 1, false, 0 or detail	Include subscriptions. Default is false. When set to detail a list with more detailed subscription information will be returned.
offset	number > 0	Pagination offset. Default is 0.
limit	number > 0	Number of results to return. Default is 1024.
cid	number, valid id	Return a connection by it's id
state	open, *closed, any	Return connections of particular state. Default is open.
mqtt_client	string	Filter the connection with this MQTT client ID.

The server will default to holding the last 10,000 closed connections.

Sort Options

Option	Sort by
cid	Connection ID
start	Connection start time, same as CID
subs	Number of subscriptions
pending	Amount of data in bytes waiting to be sent to client
msgs_to	Number of messages sent
msgs_from	Number of messages received
bytes_to	Number of bytes sent
bytes_from	Number of bytes received
last	Last activity
idle	Amount of inactivity
uptime	Lifetime of the connection
stop	Stop time for a closed connection
reason	Reason for a closed connection

Examples

Get up to 1024 connections: https://demo.nats.io:8222/connz

Control limit and offset: https://demo.nats.io:8222/connz?limit=16&offset=128.

Get closed connection information: https://demo.nats.io:8222/connz?state=closed.

You can also report detailed subscription information on a per connection basis using subs=1. For example: https://demo.nats.io:8222/connz?limit=1&offset=1&subs=1.

Response

{
  "server_id": "NACDVKFBUW4C4XA24OOT6L4MDP56MW76J5RJDFXG7HLABSB46DCMWCOW",
  "now": "2019-06-24T14:28:16.520365-07:00",
  "num_connections": 2,
  "total": 2,
  "offset": 0,
  "limit": 1024,
  "connections": [
    {
      "cid": 5,
      "kind": "Client",
      "type": "nats",
      "ip": "127.0.0.1",
      "port": 62714,
      "start": "2021-09-09T23:16:43.040862Z",
      "last_activity": "2021-09-09T23:16:43.042364Z",
      "rtt": "95µs",
      "uptime": "5s",
      "idle": "5s",
      "pending_bytes": 0,
      "in_msgs": 0,
      "out_msgs": 0,
      "in_bytes": 0,
      "out_bytes": 0,
      "subscriptions": 1,
      "name": "NATS Benchmark",
      "lang": "go",
      "version": "1.12.1"
    },
    {
      "cid": 6,
      "kind": "Client",
      "type": "nats",
      "ip": "127.0.0.1",
      "port": 62715,
      "start": "2021-09-09T23:16:43.042557Z",
      "last_activity": "2021-09-09T23:16:43.042811Z",
      "rtt": "100µs",
      "uptime": "5s",
      "idle": "5s",
      "pending_bytes": 0,
      "in_msgs": 0,
      "out_msgs": 0,
      "in_bytes": 0,
      "out_bytes": 0,
      "subscriptions": 1,
      "name": "NATS Benchmark",
      "lang": "go",
      "version": "1.12.1"
    },
    {
      "cid": 7,
      "kind": "Client",
      "type": "mqtt",
      "ip": "::1",
      "port": 62718,
      "start": "2021-09-09T23:16:45.391459Z",
      "last_activity": "2021-09-09T23:16:45.395869Z",
      "rtt": "0s",
      "uptime": "2s",
      "idle": "2s",
      "pending_bytes": 0,
      "in_msgs": 0,
      "out_msgs": 0,
      "in_bytes": 0,
      "out_bytes": 0,
      "subscriptions": 2,
      "mqtt_client": "mqtt_sub"
    }
  ]
}

Route Information

The /routez endpoint reports information on active routes for a cluster. Routes are expected to be low, so there is no paging mechanism with this endpoint.

Result	Return Code
Success	200 (OK)
Error	400 (Bad Request)

Arguments

Argument	Values	Description
subs	true, 1, false, 0 or detail	Include subscriptions. Default is false. When set to detail a list with more detailed subscription information will be returned.

As noted above, the routez endpoint does support the subs argument from the /connz endpoint. For example: https://demo.nats.io:8222/routez?subs=1

Example

• Get route information: https://demo.nats.io:8222/routez?subs=1

Response

{
  "server_id": "NACDVKFBUW4C4XA24OOT6L4MDP56MW76J5RJDFXG7HLABSB46DCMWCOW",
  "now": "2019-06-24T14:29:16.046656-07:00",
  "num_routes": 1,
  "routes": [
    {
      "rid": 1,
      "remote_id": "de475c0041418afc799bccf0fdd61b47",
      "did_solicit": true,
      "ip": "127.0.0.1",
      "port": 61791,
      "pending_size": 0,
      "in_msgs": 0,
      "out_msgs": 0,
      "in_bytes": 0,
      "out_bytes": 0,
      "subscriptions": 0
    }
  ]
}

Gateway Information

The /gatewayz endpoint reports information about gateways used to create a NATS supercluster. Like routes, the number of gateways are expected to be low, so there is no paging mechanism with this endpoint.

Result	Return Code
Success	200 (OK)
Error	400 (Bad Request)

Arguments

Argument	Values	Description
accs	true, 1, false, 0	Include account information. Default is false.
gw_name	string	Return only remote gateways with this name.
acc_name	string	Limit the list of accounts to this account name.

Examples

• Retrieve Gateway Information: https://demo.nats.io:8222/gatewayz

Response

{
  "server_id": "NANVBOU62MDUWTXWRQ5KH3PSMYNCHCEUHQV3TW3YH7WZLS7FMJE6END6",
  "now": "2019-07-24T18:02:55.597398-06:00",
  "name": "region1",
  "host": "2601:283:4601:1350:1895:efda:2010:95a1",
  "port": 4501,
  "outbound_gateways": {
    "region2": {
      "configured": true,
      "connection": {
        "cid": 7,
        "ip": "127.0.0.1",
        "port": 5500,
        "start": "2019-07-24T18:02:48.765621-06:00",
        "last_activity": "2019-07-24T18:02:48.765621-06:00",
        "uptime": "6s",
        "idle": "6s",
        "pending_bytes": 0,
        "in_msgs": 0,
        "out_msgs": 0,
        "in_bytes": 0,
        "out_bytes": 0,
        "subscriptions": 0,
        "name": "NCXBIYWT7MV7OAQTCR4QTKBN3X3HDFGSFWTURTCQ22ZZB6NKKJPO7MN4"
      }
    },
    "region3": {
      "configured": true,
      "connection": {
        "cid": 5,
        "ip": "::1",
        "port": 6500,
        "start": "2019-07-24T18:02:48.764685-06:00",
        "last_activity": "2019-07-24T18:02:48.764685-06:00",
        "uptime": "6s",
        "idle": "6s",
        "pending_bytes": 0,
        "in_msgs": 0,
        "out_msgs": 0,
        "in_bytes": 0,
        "out_bytes": 0,
        "subscriptions": 0,
        "name": "NCVS7Q65WX3FGIL2YQRLI77CE6MQRWO2Y453HYVLNMBMTVLOKMPW7R6K"
      }
    }
  },
  "inbound_gateways": {
    "region2": [
      {
        "configured": false,
        "connection": {
          "cid": 9,
          "ip": "::1",
          "port": 52029,
          "start": "2019-07-24T18:02:48.76677-06:00",
          "last_activity": "2019-07-24T18:02:48.767096-06:00",
          "uptime": "6s",
          "idle": "6s",
          "pending_bytes": 0,
          "in_msgs": 0,
          "out_msgs": 0,
          "in_bytes": 0,
          "out_bytes": 0,
          "subscriptions": 0,
          "name": "NCXBIYWT7MV7OAQTCR4QTKBN3X3HDFGSFWTURTCQ22ZZB6NKKJPO7MN4"
        }
      }
    ],
    "region3": [
      {
        "configured": false,
        "connection": {
          "cid": 4,
          "ip": "::1",
          "port": 52025,
          "start": "2019-07-24T18:02:48.764577-06:00",
          "last_activity": "2019-07-24T18:02:48.764994-06:00",
          "uptime": "6s",
          "idle": "6s",
          "pending_bytes": 0,
          "in_msgs": 0,
          "out_msgs": 0,
          "in_bytes": 0,
          "out_bytes": 0,
          "subscriptions": 0,
          "name": "NCVS7Q65WX3FGIL2YQRLI77CE6MQRWO2Y453HYVLNMBMTVLOKMPW7R6K"
        }
      },
      {
        "configured": false,
        "connection": {
          "cid": 8,
          "ip": "127.0.0.1",
          "port": 52026,
          "start": "2019-07-24T18:02:48.766173-06:00",
          "last_activity": "2019-07-24T18:02:48.766999-06:00",
          "uptime": "6s",
          "idle": "6s",
          "pending_bytes": 0,
          "in_msgs": 0,
          "out_msgs": 0,
          "in_bytes": 0,
          "out_bytes": 0,
          "subscriptions": 0,
          "name": "NCKCYK5LE3VVGOJQ66F65KA27UFPCLBPX4N4YOPOXO3KHGMW24USPCKN"
        }
      }
    ]
  }
}

Leaf Node Information

The /leafz endpoint reports detailed information about the leaf node connections.

Result	Return Code
Success	200 (OK)
Error	400 (Bad Request)

Arguments

Argument	Values	Description
subs	true, 1, false, 0	Include internal subscriptions. Default is false.

As noted above, the leafz endpoint does support the subs argument from the /connz endpoint. For example: https://demo.nats.io:8222/leafz?subs=1

Example

• Get leaf nodes information: https://demo.nats.io:8222/leafz?subs=1

Response

{
  "server_id": "NC2FJCRMPBE5RI5OSRN7TKUCWQONCKNXHKJXCJIDVSAZ6727M7MQFVT3",
  "now": "2019-08-27T09:07:05.841132-06:00",
  "leafnodes": 1,
  "leafs": [
    {
      "account": "$G",
      "ip": "127.0.0.1",
      "port": 6223,
      "rtt": "200µs",
      "in_msgs": 0,
      "out_msgs": 10000,
      "in_bytes": 0,
      "out_bytes": 1280000,
      "subscriptions": 1,
      "subscriptions_list": [
        "foo"
      ]
    }
  ]
}

Subscription Routing Information

The /subsz endpoint reports detailed information about the current subscriptions and the routing data structure. It is not normally used.

Result	Return Code
Success	200 (OK)
Error	400 (Bad Request)

Arguments

Argument	Values	Description
subs	true, 1, false, 0	Include subscriptions. Default is false.
offset	integer > 0	Pagination offset. Default is 0.
limit	integer > 0	Number of results to return. Default is 1024.
test	subject	Test whether a subsciption exists.

Example

• Get subscription routing information: https://demo.nats.io:8222/subsz

Response

{
  "num_subscriptions": 2,
  "num_cache": 0,
  "num_inserts": 2,
  "num_removes": 0,
  "num_matches": 0,
  "cache_hit_rate": 0,
  "max_fanout": 0,
  "avg_fanout": 0
}

Account Information

The /accountz endpoint reports information on a server's active accounts. The default behavior is to return a list of all accounts known to the server.

Result	Return Code
Success	200 (OK)
Error	400 (Bad Request)

Argument	Value	Description
acc	account name	Include metrics for the specified account. Default is empty. When not set, a list of all accounts is included.

Example

• Get list of all accounts: https://demo.nats.io:8222/accountz

• Get details for specific account $G: https://demo.nats.io:8222/accountz?acc=$G

Response

Default behavior:

{
  "server_id": "NAB2EEQ3DLS2BHU4K2YMXMPIOOOAOFOAQAC5NQRIEUI4BHZKFBI4ZU4A",
  "now": "2021-02-08T17:31:29.551146-05:00",
  "system_account": "AAAXAUVSGK7TCRHFIRAS4SYXVJ76EWDMNXZM6ARFGXP7BASNDGLKU7A5",
  "accounts": [
    "AAAXAUVSGK7TCRHFIRAS4SYXVJ76EWDMNXZM6ARFGXP7BASNDGLKU7A5",
    "$G"
  ]
}

Retrieve specific account:

{
  "server_id": "NAB2EEQ3DLS2BHU4K2YMXMPIOOOAOFOAQAC5NQRIEUI4BHZKFBI4ZU4A",
  "now": "2021-02-08T17:37:55.80856-05:00",
  "system_account": "AAAXAUVSGK7TCRHFIRAS4SYXVJ76EWDMNXZM6ARFGXP7BASNDGLKU7A5",
  "account_detail": {
    "account_name": "AAAXAUVSGK7TCRHFIRAS4SYXVJ76EWDMNXZM6ARFGXP7BASNDGLKU7A5",
    "update_time": "2021-02-08T17:31:22.390334-05:00",
    "is_system": true,
    "expired": false,
    "complete": true,
    "jetstream_enabled": false,
    "leafnode_connections": 0,
    "client_connections": 0,
    "subscriptions": 42,
    "exports": [
      {
        "subject": "$SYS.DEBUG.SUBSCRIBERS",
        "type": "service",
        "response_type": "Singleton"
      }
    ],
    "jwt": "eyJ0eXAiOiJqd3QiLCJhbGciOiJlZDI1NTE5In0.eyJqdGkiOiJVVlU2VEpXRU8zS0hYWTZVMkgzM0RCVklET1A3U05DTkJPMlM0M1dPNUM2T1RTTDNVSUxBIiwiaWF0IjoxNjAzNDczNzg4LCJpc3MiOiJPQlU1TzVGSjMyNFVEUFJCSVZSR0Y3Q05FT0hHTFBTN0VZUEJUVlFaS1NCSElJWklCNkhENjZKRiIsIm5hbWUiOiJTWVMiLCJzdWIiOiJBQUFYQVVWU0dLN1RDUkhGSVJBUzRTWVhWSjc2RVdETU5YWk02QVJGR1hQN0JBU05ER0xLVTdBNSIsInR5cGUiOiJhY2NvdW50IiwibmF0cyI6eyJsaW1pdHMiOnsic3VicyI6LTEsImNvbm4iOi0xLCJsZWFmIjotMSwiaW1wb3J0cyI6LTEsImV4cG9ydHMiOi0xLCJkYXRhIjotMSwicGF5bG9hZCI6LTEsIndpbGRjYXJkcyI6dHJ1ZX19fQ.CeGo16i5oD0b1uBJ8UdGmLH-l9dL8yNqXHggkAt2T5c88fM7k4G08wLguMAnlvzrdlYvdZvOx_5tHLuDZmGgCg",
    "issuer_key": "OBU5O5FJ324UDPRBIVRGF7CNEOHGLPS7EYPBTVQZKSBHIIZIB6HD66JF",
    "name_tag": "SYS",
    "decoded_jwt": {
      "jti": "UVU6TJWEO3KHXY6U2H33DBVIDOP7SNCNBO2S43WO5C6OTSL3UILA",
      "iat": 1603473788,
      "iss": "OBU5O5FJ324UDPRBIVRGF7CNEOHGLPS7EYPBTVQZKSBHIIZIB6HD66JF",
      "name": "SYS",
      "sub": "AAAXAUVSGK7TCRHFIRAS4SYXVJ76EWDMNXZM6ARFGXP7BASNDGLKU7A5",
      "nats": {
        "limits": {
          "subs": -1,
          "data": -1,
          "payload": -1,
          "imports": -1,
          "exports": -1,
          "wildcards": true,
          "conn": -1,
          "leaf": -1
        },
        "default_permissions": {
          "pub": {},
          "sub": {}
        },
        "type": "account",
        "version": 1
      }
    },
    "sublist_stats": {
      "num_subscriptions": 42,
      "num_cache": 6,
      "num_inserts": 42,
      "num_removes": 0,
      "num_matches": 6,
      "cache_hit_rate": 0,
      "max_fanout": 1,
      "avg_fanout": 0.8333333333333334
    }
  }
}

Account Statistics

The /accstatz endpoint reports per-account statistics such as the number of connections, messages/bytes in/out, etc.

Result	Return Code
Success	200 (OK)
Error	400 (Bad Request)

Arguments

Argument	Values	Description
unused	true, 1, false, 0	If true, include accounts that do not have any current connections. Default is false.

Examples

• Accounts with active connections - https://demo.nats.io:8222/accstatz

• Include ones without any connections (in this case $SYS)- https://demo.nats.io:8222/accstatz?unused=1

Response

{
  "server_id": "NDJ5M4F5WAIBUA26NJ3QMH532AQPN7QNTJP3Y4SBHSHL4Y7QUAKNJEAF",
  "now": "2022-10-19T17:16:20.881296749Z",
  "account_statz": [
    {
      "acc": "default",
      "conns": 31,
      "leafnodes": 2,
      "total_conns": 33,
      "sent": {
        "msgs": 1876970,
        "bytes": 246705616
      },
      "received": {
        "msgs": 1347454,
        "bytes": 219438308
      },
      "slow_consumers": 29
    },
    {
      "acc": "$G",
      "conns": 1,
      "leafnodes": 0,
      "total_conns": 1,
      "sent": {
        "msgs": 0,
        "bytes": 0
      },
      "received": {
        "msgs": 107,
        "bytes": 1094
      },
      "slow_consumers": 0
    }
  ]
}

JetStream Information

The /jsz endpoint reports more detailed information on JetStream. For accounts, it uses a paging mechanism that defaults to 1024 connections.

Note: If you're in a clustered environment, it is recommended to retrieve the information from the stream's leader in order to get the most accurate and up-to-date data.

Result	Return Code
Success	200 (OK)
Error	400 (Bad Request)

Arguments

Argument	Values	Description
acc	account name	Include metrics for the specified account. Default is unset.
accounts	true, 1, false, 0	Include account specific JetStream information. Default is false.
streams	true, 1, false, 0	Include streams. When set, implies accounts=true. Default is false.
consumers	true, 1, false, 0	Include consumer. When set, implies streams=true. Default is false.
config	true, 1, false, 0	When stream or consumer are requested, include their respective configuration. Default is false.
leader-only	true, 1, false, 0	Only the leader responds. Default is false.
offset	number > 0	Pagination offset. Default is 0.
limit	number > 0	Number of results to return. Default is 1024.

Examples

Get basic JetStream information: https://demo.nats.io:8222/jsz

Request accounts and control limit and offset: https://demo.nats.io:8222/jsz?accounts=true&limit=16&offset=128.

You can also report detailed consumer information on a per connection basis using consumer=true. For example: https://demo.nats.io:8222/jsz?consumers=true.

Response

{
  "server_id": "NCVIDODSZ45C5OD67ZD7EJUIJPQDP6CM74SJX6TJIF2G7NLYS5LCVYHS",
  "now": "2021-02-08T19:08:30.555533-05:00",
  "config": {
    "max_memory": 10485760,
    "max_storage": 10485760,
    "store_dir": "/var/folders/9h/6g_c9l6n6bb8gp331d_9y0_w0000gn/T/srv_7500251552558"
  },
  "memory": 0,
  "storage": 66,
  "api": {
    "total": 5,
    "errors": 0
  },
  "total_streams": 1,
  "total_consumers": 1,
  "total_messages": 1,
  "total_message_bytes": 33,
  "meta_cluster": {
    "name": "cluster_name",
    "replicas": [
      {
        "name": "server_5500",
        "current": false,
        "active": 2932926000
      }
    ]
  },
  "account_details": [
    {
      "name": "BCC_TO_HAVE_ONE_EXTRA",
      "id": "BCC_TO_HAVE_ONE_EXTRA",
      "memory": 0,
      "storage": 0,
      "api": {
        "total": 0,
        "errors": 0
      }
    },
    {
      "name": "ACC",
      "id": "ACC",
      "memory": 0,
      "storage": 66,
      "api": {
        "total": 5,
        "errors": 0
      },
      "stream_detail": [
        {
          "name": "my-stream-replicated",
          "cluster": {
            "name": "cluster_name",
            "replicas": [
              {
                "name": "server_5500",
                "current": false,
                "active": 2931517000
              }
            ]
          },
          "state": {
            "messages": 1,
            "bytes": 33,
            "first_seq": 1,
            "first_ts": "2021-02-09T00:08:27.623735Z",
            "last_seq": 1,
            "last_ts": "2021-02-09T00:08:27.623735Z",
            "consumer_count": 1
          },
          "consumer_detail": [
            {
              "stream_name": "my-stream-replicated",
              "name": "my-consumer-replicated",
              "created": "2021-02-09T00:08:27.427631Z",
              "delivered": {
                "consumer_seq": 0,
                "stream_seq": 0
              },
              "ack_floor": {
                "consumer_seq": 0,
                "stream_seq": 0
              },
              "num_ack_pending": 0,
              "num_redelivered": 0,
              "num_waiting": 0,
              "num_pending": 1,
              "cluster": {
                "name": "cluster_name",
                "replicas": [
                  {
                    "name": "server_5500",
                    "current": false,
                    "active": 2933232000
                  }
                ]
              }
            }
          ]
        }
      ]
    }
  ]
}

Health

The /healthz endpoint returns OK if the server is able to accept connections.

Result	Return Code
Success	200 (OK)
Error	400 (Bad Request)

Arguments

Argument	Values	Description
js-enabled	true, 1	Returns an error if JetStream is disabled.
js-server-only	true, 1	Skip health check of accounts, streams, and consumers.

Example

• Default - https://demo.nats.io:8222/healthz

• Expect JetStream - https://demo.nats.io:8222/healthz?js-enabled=true

Response

{"status": "ok"}

Creating Monitoring Applications

NATS monitoring endpoints support JSONP and CORS. You can easily create single page web applications for monitoring. To do this you simply pass the callback query parameter to any endpoint.

For example:

https://demo.nats.io:8222/connz?callback=cb

Here is a JQuery example implementation:

$.getJSON('https://demo.nats.io:8222/connz?callback=?', function(data) {
  console.log(data);
});

Monitoring Tools

In addition to writing custom monitoring tools, you can monitor nats-server in Prometheus. The Prometheus NATS Exporter allows you to configure the metrics you want to observe and store in Prometheus, and there are Grafana dashboards available for you to visualize the server metrics.

See the Walkthrough of Monitoring NATS with Prometheus and Grafana for more details.