nats CLI

nats CLI

A command line utility to interact with and manage NATS.

This utility replaces various past tools that were named in the form nats-sub and nats-pub, adds several new capabilities and supports full JetStream management.

Check out the repo for all the details: github.com/nats-io/natscli.

Installing `nats`

For macOS:

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

For Arch Linux:

Download the correct .deb file for your computer from here.

If you have an Intel CPU, then it’ll probably be this one (for version X.Y.Z): nats-X.Y.Z-amd64.deb Then run this command to install the file.

sudo dpkg -i nats-X.Y.Z-amd64.deb

Or with the yay package manager

yay natscli

Binaries are also available as GitHub Releases.

Using `nats`

Getting help

nats help
nats help [<command>...] or nats [<command>...] --help
Remember to look at the cheat sheets!
- nats cheat
- nats cheat --sections
- nats cheat <section>>
  Interacting with NATS
nats context
nats account
nats pub
nats sub
nats request
nats reply
nats bench
Monitoring NATS
nats events
nats rtt
nats server
nats latency
nats governor
Managing and interacting with streams
nats stream
nats consumer
nats backup
nats restore
Managing and interacting with the K/V Store
nats kv
Get reference information
nats errors
nats schema

Configuration Contexts

In practice, it is quite common for the administrators of a NATS service infrastructure to have to connect using various NATS URLs and security credentials, the CLI has a number of environment configuration settings that can be passed as command line arguments or set in environment variables. In order to facilitate switching between NATS environments or servers, clusters, operators, etc… nats lets you use ‘contexts’ that you can store and easily select.

nats --help

Output extract

...
  -s, --server=NATS_URL         NATS servers
      --user=NATS_USER          Username of Token
      --password=NATS_PASSWORD  Password
      --creds=NATS_CREDS        User credentials
      --nkey=NATS_NKEY          User NKEY
      --tlscert=NATS_CERT       TLS public certificate
      --tlskey=NATS_KEY         TLS private key
      --tlsca=NATS_CA           TLS certificate authority chain
      --timeout=NATS_TIMEOUT    Time to wait on responses from NATS
      --context=CONTEXT         NATS Configuration Context to use for access
...

You can set these using the CLI flag, the environment variable - like NATS_URL - or using our context feature.

NATS Contexts

A context is a named configuration that stores all of these settings, you can switch between access configurations and designate a default.

Creating one is easy, just specify the settings with nats context save

nats context save example --server nats://nats.example.net:4222 --description 'Example.Net Server'
nats context save local --server nats://localhost:4222 --description 'Local Host' --select

Or you can use nats context create my_context_name and then edit the created context file (i.e. in ~/.config/nats/context/my_context_name.json)

List your contexts

nats context ls

Output

Known contexts:
   example             Example.Net Server
   local*              Local Host

We passed --select to the local one meaning it will be the default when nothing is set.

Select a context

nats context select

Check the round trip time to the server (using the currently selected context)

nats rtt

Output

nats://localhost:4222:
   nats://127.0.0.1:4222: 245.115µs
       nats://[::1]:4222: 390.239µs

You can also specify a context directly

nats rtt --context example

Example output

nats://nats.example.net:4222:
   nats://192.0.2.10:4222: 41.560815ms
   nats://192.0.2.11:4222: 41.486609ms
   nats://192.0.2.12:4222: 41.178009ms

All nats commands are context aware and the nats context command has various commands to view, edit and remove contexts.

Server URLs and Credential paths can be resolved via the nsc command by specifying an URL, for example to find user new within the orders account of the acme operator you can use this:

nats context save example --description 'Example.Net Server' --nsc nsc://acme/orders/new

The server list and credentials path will now be resolved via nsc, if these are specifically set in the context, the specific context configuration will take precedence.

Generating bcrypted passwords

The server supports hashing of passwords and authentication tokens using bcrypt. To take advantage of this, simply replace the plaintext password in the configuration with its bcrypt hash, and the server will automatically utilize bcrypt as needed.

The nats utility has a command for creating bcrypt hashes. This can be used for a password or a token in the configuration.

nats server passwd

Output

? Enter password [? for help] **********************
? Reenter password [? for help] **********************
$2a$11$3kIDaCxw.Glsl1.u5nKa6eUnNDLV5HV9tIuUp7EHhMt6Nm9myW1aS

To use the password on the server, add the hash into the server configuration file’s authorization section.

  authorization {
    user: derek
    password: $2a$11$3kIDaCxw.Glsl1.u5nKa6eUnNDLV5HV9tIuUp7EHhMt6Nm9myW1aS
  }

Note the client will still have to provide the plain text version of the password, the server however will only store the hash to verify that the password is correct when supplied.