Monitoring
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:
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:
As a command-line option:
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
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 | Include subscriptions. Default is false. When set to |
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 its 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 |
rtt | Round trip time |
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
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 | Include subscriptions. Default is false. When set to |
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
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
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
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
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:
Retrieve specific account:
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
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 |
consumers | true, 1, false, 0 | Include consumer. When set, implies |
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. |
raft | true, 1, false, 0 | Include information details about the Raft group. Default is false. |
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
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-only | true, 1 | Returns an error if JetStream is disabled. |
js-server-only | true, 1 | Skip health check of accounts, streams, and consumers. |
js-enabled | true, 1 | Returns an error if JetStream is disabled. (Deprecated: use |
Example
Default - https://demo.nats.io:8222/healthz
Expect JetStream - https://demo.nats.io:8222/healthz?js-enabled-only=true
Response
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:
Here is a JQuery example implementation:
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.
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