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Introduction to NATS CLI

11 min read


In this article, we'll take a look at NATS CLI and learn some basics commands. In my opinion NATS CLI is quite underrated, it offers many features and can help eliminate most of the manual scripts used to manage a NATS server.


For OS X brew can be used to install the latest version:

$ brew tap nats-io/nats-tools
$ brew install nats-io/nats-tools/nats

For more installation options, check Github releases


  • JetStream management
  • JetStream data and configuration backup
  • Message publish and subscribe
  • Service requests and creation
  • Benchmarking and Latency testing
  • Super Cluster observation
  • Configuration context maintenance
  • NATS ecosystem schema registry


Let's learn about some basic commands. But first, let's start our nats-server locally with JetStream so that we can try out the commands.

Note: To enable JetStream we can use the -js or --jetstream flag.

$ nats-server -js
[48351] 2022/04/04 17:01:50.947435 [INF] Starting nats-server
[48351] 2022/04/04 17:01:50.947518 [INF]   Version:  2.7.4
[48351] 2022/04/04 17:01:50.947521 [INF]   Git:      [not set]
[48351] 2022/04/04 17:01:50.947524 [INF]   Name:     NDYZJMTC6C6D2DJHVJEPWOF5SE4BZVKE5WFDJOUBFYE6JMP5EUDL27SZ
[48351] 2022/04/04 17:01:50.947529 [INF]   Node:     MiRXijo7
[48351] 2022/04/04 17:01:50.947532 [INF]   ID:       NDYZJMTC6C6D2DJHVJEPWOF5SE4BZVKE5WFDJOUBFYE6JMP5EUDL27SZ
[48351] 2022/04/04 17:01:50.947792 [INF] Starting JetStream
[48351] 2022/04/04 17:01:50.948188 [INF]     _ ___ _____ ___ _____ ___ ___   _   __  __
[48351] 2022/04/04 17:01:50.948202 [INF]  _ | | __|_   _/ __|_   _| _ \ __| /_\ |  \/  |
[48351] 2022/04/04 17:01:50.948204 [INF] | || | _|  | | \__ \ | | |   / _| / _ \| |\/| |
[48351] 2022/04/04 17:01:50.948206 [INF]  \__/|___| |_| |___/ |_| |_|_\___/_/ \_\_|  |_|
[48351] 2022/04/04 17:01:50.948207 [INF]
[48351] 2022/04/04 17:01:50.948209 [INF]
[48351] 2022/04/04 17:01:50.948211 [INF]
[48351] 2022/04/04 17:01:50.948213 [INF] ---------------- JETSTREAM ----------------
[48351] 2022/04/04 17:01:50.948217 [INF]   Max Memory:      12.00 GB
[48351] 2022/04/04 17:01:50.948221 [INF]   Max Storage:     275.69 GB
[48351] 2022/04/04 17:01:50.948223 [INF]   Store Directory: "/var/folders/zj/t9pthq5n5s109_02bq2gf13w0000gn/T/nats/jetstream"
[48351] 2022/04/04 17:01:50.948225 [INF] -------------------------------------------
[48351] 2022/04/04 17:01:50.948639 [INF] Listening for client connections on
[48351] 2022/04/04 17:01:50.948849 [INF] Server is ready


The nats CLI supports multiple named configurations. We refer to these configurations as "context". In these contexts, we can configure the server, credentials, certs, and much more.


To manage nats configuration contexts, we use the context command.

usage: nats context <command> [<args> ...]


To create or update a context we can use the context save sub-command.

$ nats context save my-context
NATS Configuration Context "my-context"

      Server URLs:
             Path: /..../.config/nats/context/my-context.json

Note: we can also use the --user and --password flags to add credentials to the context.


Now that have created our context, we can select it using the context select sub-command.

$ nats context select my-context
NATS Configuration Context "my-context"

      Server URLs:
             Path: /..../.config/nats/context/my-context.json


And now if we list known contexts using the context ls sub-command, we can see our my-context being selected.

$ nats context ls
│      Known Contexts       │
│ Name        │ Description │
│ my-context* │             │


We can also easily remove the context using the context rm sub-command.

$ nats context rm my-context
? Really delete context "my-context" Yes



We can use info command to view account information and connection

$ nats account info
Connection Information:

               Client ID: 4
               Client IP:
                     RTT: 77.542µs
       Headers Supported: true
         Maximum Payload: 1.0 MiB
           Connected URL: nats://
       Connected Address:

JetStream Account Information:

Configuration Requirements:

   Requires Max Bytes Set: false

Stream Resource Usage Limits:

      Memory: 0 B of Unlimited
     Storage: 0 B of Unlimited
     Streams: 0 of Unlimited
   Consumers: 0 of Unlimited


report connections as the name suggest report connection for our command

$ nats account report connections

│                                                                          Top 1 Connections out of 1 by subs                                                                          │
│ CID │ Name                    │ Server                                                   │ Cluster │ IP        │ Account │ Uptime │ In Msgs │ Out Msgs │ In Bytes │ Out Bytes │ Subs │
5   │ NATS CLI Version 0.0.30 │ ND5TMCZ32LWFSFQGTMMADGCERCQE4C6A2P6DAVPK76WFE4LAM56AZ26N │         │ │         │ 0s     │ 000 B      │ 0 B       │ 1╰─────┴─────────────────────────┴──────────────────────────────────────────────────────────┴─────────┴───────────┴─────────┴────────┴─────────┴──────────┴──────────┴───────────┴──────╯

│                              Connections per server                              │
│ Server                                                   │ Cluster │ Connections │
│ ND5TMCZ32LWFSFQGTMMADGCERCQE4C6A2P6DAVPK76WFE4LAM56AZ26N │         │ 1╰──────────────────────────────────────────────────────────┴─────────┴─────────────╯


publish command is a generic data publish utility. This is useful to quickly publish and test without having to write a script.


nats publish [<flags>] <subject> [<body>]

Let's try to publish some data on the subject hello

$ nats publish hello my-data
14:09:46 Published 7 bytes to "hello"

Note: To publish multiple messages, we can use the --count flag


Similarly to publish command we also have subscribe command which acts as a generic subscription client.


nats subscribe [<flags>] [<subject>]

To try out subscribe command first, we will subscribe to the hello subject and then publish some data on the same subject using the nats publish "hello there" command.

$ nats subscribe hello
14:13:20 Subscribing on hello
[#1] Received on "hello"
hi there

Note: Learn more about publish/subscribe in the distributed communication patterns in NATS article.


request command is a generic request-reply request utility.


nats request <subject>


$ nats request hello
14:43:06 Reading payload from STDIN


reply command gives us access to the generic service reply utility. The "command" supports extracting some information from the subject the request came in on.


nats reply <subject> <data>


$ nats reply hello data
14:48:36 Listening on "hello" in group "NATS-RPLY-22"

We can also use request/reply together to measure latency. For example, using nats bench --reply and nats bench --request in two terminals at the same time. Then we can invert the number of requests per second to get the latency.

Note: Learn more about request/reply in the distributed communication patterns in NATS article.


NATS KV is a JetStream based Key-Value store. Key-Value stores are specialized NoSQL databases that store values in a data bucket under a specific key.


Before we start storing our key-value pairs, we need to create a config. For this, let's add a custom my-config. This config helps us create a new bucket with built-in replication.

Note: KV requires JetSteam to be enabled.

$ nats kv add my-config
my-config Key-Value Store Status

         Bucket Name: my-config
        History Kept: 1
       Values Stored: 0
  Backing Store Kind: JetStream
 Maximum Bucket Size: unlimited
  Maximum Value Size: unlimited
    JetStream Stream: KV_my-config
            Storage: File


Once we have the config, we have PUT or GET our key-value pairs. In the example below, we will store value myvalue in the key mykey and later retrieve it.

$ nats kv put my-config mykey myvalue

$ nats kv get my-config mykey
my-config > mykey created @ 04 Apr 22 11:32 UTC



bench command might be the most used command. This is basically a benchmark utility that comes with the CLI.

Basic Usage

nats bench [<flags>] <subject>

Example Here, we are using the bench command to benchmark our NATS server with 1 million message with 2 publisher and 2 subscribers on the test subject.

$ nats bench --msgs 1000000 --pub 2 --sub 2 test
14:57:01 Starting pub/sub benchmark [subject=test, msgs=1,000,000, msgsize=128 B, pubs=2, subs=2, js=false, pubsleep=0s, subsleep=0s]
14:57:01 Starting subscriber, expecting 1,000,000 messages
14:57:01 Starting subscriber, expecting 1,000,000 messages
14:57:01 Starting publisher, publishing 500,000 messages
14:57:01 Starting publisher, publishing 500,000 messages
Finished      0s [===============================================] 100%
Finished      0s [===============================================] 100%
Finished      0s [===============================================] 100%
Finished      0s [===============================================] 100%

NATS Pub/Sub stats: 7,907,082 msgs/sec ~ 965.22 MB/sec
 Pub stats: 3,060,110 msgs/sec ~ 373.55 MB/sec
  [1] 1,541,921 msgs/sec ~ 188.22 MB/sec (500000 msgs)
  [2] 1,530,055 msgs/sec ~ 186.77 MB/sec (500000 msgs)
  min 1,530,055 | avg 1,535,988 | max 1,541,921 | stddev 5,933 msgs
 Sub stats: 5,275,380 msgs/sec ~ 643.97 MB/sec
  [1] 2,680,372 msgs/sec ~ 327.19 MB/sec (1000000 msgs)
  [2] 2,638,306 msgs/sec ~ 322.06 MB/sec (1000000 msgs)
  min 2,638,306 | avg 2,659,339 | max 2,680,372 | stddev 21,033 msgs


We can also use --js with --pub to publish first and replay using --js --pull and --sub to separately measure the speed of putting and getting messages from the stream.

# Put messages in the stream
$ nats bench --msgs 1000000 --pub 2 test --js

# Pull messages from the stream
$ nats bench --msgs 1000000 --sub 2 test --js --pull

Note: We can use the bench command not just to see how fast it goes "all out" but to also generate traffic (using --pubsleep ) and processing times (using --subsleep )


events command shows advisories and events in the NATS server.

$ nats events
Listening for Client Connection events on $SYS.ACCOUNT.*.CONNECT
Listening for Client Disconnection events on $SYS.ACCOUNT.*.DISCONNECT
Listening for Authentication Errors events on $SYS.SERVER.*.CLIENT.AUTH.ERR


cheat is arguably the most awesome command. It helps us see what's all there is in the NATS CLI in a quick and easy-to-digest format.

$ nats cheat --sections
Known sections:


Now, we can simply view info about any of the sections like the following:

$ nats cheat account
# To view account information and connection
nats account info

# To report connections for your command
nats account report connections

Note: We can also use the nats <cmd> --help to get some info about the commands.


In this article, we took a brief look at NATS CLI and learned about some basic CLI commands. This will help us to manage our NATS server easily and any extra dependency! Feel free to reachout if you have any questions.

© 2022 Karan Pratap Singh