JetStream

This mini-tutorial shows how to run a NATS server with JetStream enabled in a local Docker container. This enables quick and consequence-free experimentation with the many features of JetStream.

Using the official nats image, start a server. The -js option is passed to the server to enable JetStream. The -p option forwards your local 4222 port to the server inside the container, 4222 is the default client connection port.

docker run -p 4222:4222 nats -js

To persist JetStream data to a volume, you can use the -v option in combination with -sd:

docker run -p 4222:4222 -v nats:/data nats -js -sd /data

With the server running, use nats bench to create a stream and publish some messages to it.

nats bench -s localhost:4222 benchsubject --js --pub 1 --msgs=100000

JetStream persists the messages (on disk by default). Now consume them with:

nats bench -s localhost:4222 benchsubject --js --sub 3 --msgs=100000

You can use nats to inspect various aspects of the stream, for example:

nats -s localhost:4222 stream list
╭────────────────────────────────────────────────────────────────────────────────────╮
                                       Streams                                      
├─────────────┬─────────────┬─────────────────────┬──────────┬────────┬──────────────┤
 Name         Description  Created              Messages  Size    Last Message 
├─────────────┼─────────────┼─────────────────────┼──────────┼────────┼──────────────┤
 benchstream               2024-06-07 20:26:38  100,000   16 MiB  35s          
╰─────────────┴─────────────┴─────────────────────┴──────────┴────────┴──────────────╯

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