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226 lines
6.8 KiB
Markdown
226 lines
6.8 KiB
Markdown
## Monitoring NATS
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To monitor the NATS messaging system, `nats-server` provides a lightweight HTTP server on a dedicated monitoring port. The monitoring server provides several endpoints, including [varz](#/varz), [connz](#/connz), [routez](#/routez), and [subsz](#/subz). All endpoints return a JSON object.
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The NATS monitoring endpoints support JSONP and CORS, making it easy to create single page monitoring web applications.
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### Enabling monitoring from the command line
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To enable the monitoring server, start the NATS server with the monitoring flag `-m` and the monitoring port, or turn it on in the [configuration file](configuration.md#configuration-properties).
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-m, --http_port PORT HTTP PORT for monitoring
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-ms,--https_port PORT Use HTTPS PORT for monitoring
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Example:
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```sh
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$ nats-server -m 8222
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[4528] 2019/06/01 20:09:58.572939 [INF] Starting nats-server version 2.0.0
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[4528] 2019/06/01 20:09:58.573007 [INF] Starting http monitor on port 8222
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[4528] 2019/06/01 20:09:58.573071 [INF] Listening for client connections on 0.0.0.0:4222
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[4528] 2019/06/01 20:09:58.573090 [INF] nats-server is ready</td>
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```
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To test, run `nats-server -m 8222`, then go to <a href="http://localhost:8222/" target="_blank">http://localhost:8222/</a>
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### Enable monitoring from the configuration file
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You can also enable monitoring using the configuration file as follows:
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```yaml
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http_port: 8222
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```
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## Monitoring endpoints
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The following sections describe each supported monitoring endpoint: `varz`, `connz`, `routez`, and `subsz`.
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### /varz
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The endpoint <a href="http://localhost:822/varz" target="_blank">http://localhost:8222/varz</a> reports various general statistics.
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```json
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{
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"server_id": "NACDVKFBUW4C4XA24OOT6L4MDP56MW76J5RJDFXG7HLABSB46DCMWCOW",
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"version": "2.0.0",
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"proto": 1,
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"go": "go1.12",
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"host": "0.0.0.0",
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"port": 4222,
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"max_connections": 65536,
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"ping_interval": 120000000000,
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"ping_max": 2,
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"http_host": "0.0.0.0",
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"http_port": 8222,
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"https_port": 0,
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"auth_timeout": 1,
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"max_control_line": 4096,
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"max_payload": 1048576,
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"max_pending": 67108864,
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"cluster": {},
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"gateway": {},
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"leaf": {},
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"tls_timeout": 0.5,
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"write_deadline": 2000000000,
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"start": "2019-06-24T14:24:43.928582-07:00",
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"now": "2019-06-24T14:24:46.894852-07:00",
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"uptime": "2s",
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"mem": 9617408,
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"cores": 4,
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"cpu": 0,
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"connections": 0,
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"total_connections": 0,
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"routes": 0,
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"remotes": 0,
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"in_msgs": 0,
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"out_msgs": 0,
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"in_bytes": 0,
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"out_bytes": 0,
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"slow_consumers": 0,
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"subscriptions": 0,
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"http_req_stats": {
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"/": 0,
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"/connz": 0,
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"/gatewayz": 0,
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"/routez": 0,
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"/subsz": 0,
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"/varz": 1
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},
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"config_load_time": "2019-06-24T14:24:43.928582-07:00"
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}
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```
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### /connz
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The endpoint <a href="http://localhost:8222/connz" target="_blank">http://localhost:8222/connz</a> reports more detailed information on current connections. It uses a paging mechanism which defaults to 1024 connections.
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You can control these via URL arguments (limit and offset). For example: <a href="http://localhost:8222/connz?limit=1&offset=1" target="_blank">http://localhost:8222/connz?limit=1&offset=1</a>.
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You can also report detailed subscription information on a per connection basis using subs=1. For example: <a href="http://localhost:8222/connz?limit=1&offset=1&subs=1" target="_blank">http://localhost:8222/connz?limit=1&offset=1&subs=1</a>.
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```json
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{
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"server_id": "NACDVKFBUW4C4XA24OOT6L4MDP56MW76J5RJDFXG7HLABSB46DCMWCOW",
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"now": "2019-06-24T14:28:16.520365-07:00",
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"num_connections": 2,
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"total": 2,
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"offset": 0,
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"limit": 1024,
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"connections": [
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{
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"cid": 1,
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"ip": "127.0.0.1",
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"port": 49764,
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"start": "2019-06-24T14:27:25.94611-07:00",
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"last_activity": "2019-06-24T14:27:25.954046-07:00",
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"rtt": "275µs",
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"uptime": "50s",
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"idle": "50s",
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"pending_bytes": 0,
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"in_msgs": 0,
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"out_msgs": 0,
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"in_bytes": 0,
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"out_bytes": 0,
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"subscriptions": 1,
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"name": "NATS Sample Subscriber",
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"lang": "go",
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"version": "1.8.1",
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"subscriptions_list": [
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"hello.world"
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]
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},
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{
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"cid": 2,
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"ip": "127.0.0.1",
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"port": 49767,
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"start": "2019-06-24T14:27:43.403923-07:00",
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"last_activity": "2019-06-24T14:27:43.406568-07:00",
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"rtt": "96µs",
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"uptime": "33s",
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"idle": "33s",
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"pending_bytes": 0,
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"in_msgs": 0,
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"out_msgs": 0,
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"in_bytes": 0,
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"out_bytes": 0,
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"subscriptions": 1,
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"name": "NATS Sample Subscriber",
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"lang": "go",
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"version": "1.8.1",
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"subscriptions_list": [
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"foo.bar"
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]
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}
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]
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}
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```
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### /routez
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The endpoint <a href="http://localhost:8222/routez" target="_blank">http://localhost:8222/routez</a> reports information on active routes for a cluster. Routes are expected to be low, so there is no paging mechanism with this endpoint.
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The `routez` endpoint does support the `subs` argument from the `/connz` endpoint. For example: <a href="http://localhost:8222/routez?subs=1" target="_blank">http://localhost:8222/routez?subs=1</a>
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```json
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{
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"server_id": "NACDVKFBUW4C4XA24OOT6L4MDP56MW76J5RJDFXG7HLABSB46DCMWCOW",
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"now": "2019-06-24T14:29:16.046656-07:00",
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"num_routes": 1,
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"routes": [
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{
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"rid": 1,
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"remote_id": "de475c0041418afc799bccf0fdd61b47",
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"did_solicit": true,
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"ip": "127.0.0.1",
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"port": 61791,
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"pending_size": 0,
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"in_msgs": 0,
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"out_msgs": 0,
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"in_bytes": 0,
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"out_bytes": 0,
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"subscriptions": 0
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}
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]
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}
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```
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### /subsz
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The endpoint <a href="http://localhost:8222/subz" target="_blank">http://localhost:8222/subz</a> reports detailed information about the current subscriptions and the routing data structure.
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```json
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{
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"num_subscriptions": 2,
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"num_cache": 0,
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"num_inserts": 2,
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"num_removes": 0,
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"num_matches": 0,
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"cache_hit_rate": 0,
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"max_fanout": 0,
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"avg_fanout": 0
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}
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```
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## Creating monitoring applications
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NATS monitoring endpoints support [JSONP](https://en.wikipedia.org/wiki/JSONP) and [CORS](https://en.wikipedia.org/wiki/Cross-origin_resource_sharing#How_CORS_works). You can easily create single page web applications for monitoring. To do this you simply pass the `callback` query parameter to any endpoint.
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For example:
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```sh
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http://localhost:8222/connz?callback=cb
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```
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Here is a JQuery example implementation:
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```javascript
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$.getJSON('http://localhost:8222/connz?callback=?', function(data) {
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console.log(data);
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});
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```
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## Monitoring Tools
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In addition to writing custom monitoring tools, you can monitor nats-server in Prometheus. The [Prometheus NATS Exporter](https://github.com/nats-io/prometheus-nats-exporter) allows you to configure the metrics you want to observe and store in Prometheus. There's a sample [Grafana](https://grafana.com) dashboard that you can use to visualize the server metrics.
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