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101 lines
3.4 KiB
Markdown
101 lines
3.4 KiB
Markdown
# Monitoring
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To monitor the NATS Streaming system, a lightweight HTTP server is used on a dedicated monitoring port. The monitoring server provides several endpoints, all returning a JSON object.
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## Enabling from the command line
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To enable the monitoring server, start the NATS Streaming Server with the monitoring flag -m \(or -ms\) and specify the monitoring port.
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Monitoring options
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```text
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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 (requires TLS cert and key)
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```
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To enable monitoring via the configuration file, use `http: "host:port"` or `https: "host:port"`. There is no explicit configuration flag for the monitoring interface.
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For example, after running this:
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```text
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nats-streaming-server -m 8222
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```
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you should see that the NATS Streaming server starts with the HTTP monitoring port enabled:
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```bash
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[19339] 2019/06/24 15:02:38.251091 [INF] STREAM: Starting nats-streaming-server[test-cluster] version 0.15.1
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[19339] 2019/06/24 15:02:38.251238 [INF] STREAM: ServerID: 0Z2HXClEM6BPsGaKcoHg5N
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[19339] 2019/06/24 15:02:38.251243 [INF] STREAM: Go version: go1.12
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[19339] 2019/06/24 15:02:38.251862 [INF] Starting nats-server version 2.0.0
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[19339] 2019/06/24 15:02:38.251873 [INF] Git commit [not set]
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[19339] 2019/06/24 15:02:38.252173 [INF] Starting http monitor on 0.0.0.0:8222
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[19339] 2019/06/24 15:02:38.252248 [INF] Listening for client connections on 0.0.0.0:4222
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(...)
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```
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You can then point your browser \(or curl\) to [http://localhost:8222/streaming](http://localhost:8222/streaming)
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## Enabling from the configuration file
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To start via the configuration file you can define the monitoring port as follows:
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```text
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http_port = 8222
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```
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Then use the `-sc` flag to customize the NATS Streaming configuration:
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```bash
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nats-streaming-server -sc nats-streaming.conf -ns nats://demo.nats.io:4222 -SDV
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```
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Confirm that the monitoring endpoint is enabled by sending a request:
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```bash
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curl 127.0.0.1:8222/streaming/channelsz
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{
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"cluster_id": "test-cluster",
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"server_id": "dXUsNRef1z25NpcFmZhBNj",
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"now": "2019-06-24T15:18:37.388938-07:00",
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"offset": 0,
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"limit": 1024,
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"count": 0,
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"total": 0
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}
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```
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## Monitoring a NATS Streaming channel with Grafana and Prometheus
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Here you'll find examples demonstrating how to use Prometheus query expressions to monitor NATS streaming channels.
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### Pending Messages from Channel Foo
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```text
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sum(nss_chan_subs_pending_count{channel="foo"}) by (client_id)
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```
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### Messages Per Sec Delivered on Channel Foo
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In this case, `3` is the size of the quorum of NATS Streaming Server nodes. In case of a single instance backed by a relational database we would set it to `1`:
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```text
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sum(rate(nss_chan_msgs_total{channel="foo"}[5m])) by (channel) / 3
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```
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### Msgs/Sec vs Pending on Channel
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Example of combining the rate of messages with the pending count to detect whether processing is getting behind:
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```text
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sum(rate(nss_chan_msgs_total{channel="foo"}[5m])) by (channel) / 3
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sum(nss_chan_subs_pending_count{channel="foo"}) by (channel) / 3
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```
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