nats-top

nats-top is a top-like tool for monitoring nats-server servers.

The nats-top functionality is now available in the nats CLI tool using the nats top command.

The nats-top tool provides a dynamic real-time view of a NATS server. nats-top can display a variety of system summary information about the NATS server, such as subscription, pending bytes, number of messages, and more, in real time. For example:

nats-top

nats-server version 0.6.4 (uptime: 31m42s)
Server:
  Load: CPU: 0.8%   Memory: 5.9M  Slow Consumers: 0
  In:   Msgs: 34.2K  Bytes: 3.0M  Msgs/Sec: 37.9  Bytes/Sec: 3389.7
  Out:  Msgs: 68.3K  Bytes: 6.0M  Msgs/Sec: 75.8  Bytes/Sec: 6779.4

Connections: 4
  HOST                 CID      SUBS    PENDING     MSGS_TO     MSGS_FROM   BYTES_TO    BYTES_FROM  LANG     VERSION SUBSCRIPTIONS
  127.0.0.1:56134      2        5       0           11.6K       11.6K       1.1M        905.1K      go       1.1.0   foo, hello
  127.0.1.1:56138      3        1       0           34.2K       0           3.0M        0           go       1.1.0    _INBOX.a96f3f6853616154d23d1b5072
  127.0.0.1:56144      4        5       0           11.2K       11.1K       873.5K      1.1M        go       1.1.0   foo, hello
  127.0.0.1:56151      5        8       0           11.4K       11.5K       1014.6K     1.0M        go       1.1.0   foo, hello

Installation

nats-top can be installed using go install. For example:

go install github.com/nats-io/nats-top

With newer versions of Go, you will be required to use go install github.com/nats-io/nats-top@latest.

NOTE: You may have to run the above command as user sudo depending on your setup. If you receive an error that you cannot install nats-top because your $GOPATH is not set, when in fact it is set, use command sudo -E go get github.com/nats-io/nats-top to install nats-top. The -E flag tells sudo to preserve the current user's environment.

Usage

Once installed, nats-top can be run with the command nats-top and optional arguments.

nats-top [-s server] [-m monitor] [-n num_connections] [-d delay_in_secs] [-sort by]

Options

Optional arguments inclde the following:

Option	Description
-m monitor	Monitoring http port from nats-server.
-n num_connections	Limit the connections requested to the server (default 1024).
-d delay_in_secs	Screen refresh interval (default 1 second).
-sort by	Field to use for sorting the connections (see below).

Commands

While in nats-top view, you can use the following commands.

option

Use the o<option> command to set the primary sort key to the <option> value. The option value can be one of the following: cid, subs, pending, msgs_to, msgs_from, bytes_to, bytes_from, lang, version.

You can also set the sort option on the command line using the -sort flag. For example: nats-top -sort bytes_to.

limit

Use the n<limit> command to set the sample size of connections to request from the server.

You can also set this on the command line using the -n num_connections flag. For example: nats-top -n 1.

Note that if n<limit> is used in conjunction with -sort, the server will respect both options allowing queries such as the following: Query for the connection with largest number of subscriptions: nats-top -n 1 -sort subs.

s, ? and q Commands

Use the s command to toggle displaying connection subscriptions.

Use the ? command to show help message with options.

Use the q command to quit nats-top.

Tutorial

For a walkthrough with nats-top check out the tutorial.