Bevygap NATS Setup

Now that nats-cli can connect to your NATS server, and we know it's working, let's ensure that the bevygap code can connect too.

Bevygap Required Environment Variables

bevygap_matchmaker, bevygap_httpd,and the gameservers (via bevygap_server_plugin) need to connect to NATS.

The NATS connection code in bevygap_shared depends on the following environment variables to set up the NATS connection.

Variable	Required	Description
NATS_HOST	Yes	NATS server address eg: `nats.example.com:4222` or `1.2.3.4`
NATS_USER	Yes	Username for NATS authentication
NATS_PASSWORD	Yes	Password for NATS authentication
NATS_CA	No	Path to CA root certificate for self-signed certs eg: `/path/to/rootCA.pem`
NATS_CA_CONTENTS	No	Contents of the CA file gets written to tmp file and used as NATS_CA 255 byte limit on edgegap for ENVS see note about `set-caroot-argument.sh` in 'Edgegap Setup' section

Create nats.env file

Back on your local machine, in the bevygap directory, copy nats.env.example to nats.env, and edit it with your server's IP address, nats user, nats password, and path to CA certificate.

nats.env:

NATS_USER=matchmaker
NATS_PASSWORD=matchmaker
NATS_HOST=1.2.3.4
NATS_CA="/Users/rj/Library/Application Support/mkcert/rootCA.pem"

Our docker-compose.yaml file will apply these environment variables to containers we run, but we also want to set them in our shell, before we run (eg) the bevygap matchmaker service using cargo run.

# Setting environment variables in bash, on linux/mac
export NATS_USER=....
export NATS_PASSWORD=....
# Bash trick to set them from the .env file:
set -a && . ./nats.env && set +a

# How do you do this in windows? something like this maybe:
setx NATS_USER "matchmaker"

Verify your environment variables are set:

$ echo $NATS_USER
matchmaker # <-- your nats username should be printed here

The final test

The bevygap_shared crate has an example (non-bevy) program that connects to NATS and prints a success message then exits. This will test that your environment variables are set correctly for bevygap:

$ cargo run -p bevygap_shared --example nats
     ...compiling...
     Running `target/debug/examples/nats`
2024-11-04T09:49:23.764924Z  INFO bevygap_shared: NATS: setting up, client name: bevygap_nats_test    
2024-11-04T09:49:23.765494Z  INFO bevygap_shared: NATS: TLS is enabled    
2024-11-04T09:49:23.765498Z  INFO bevygap_shared: NATS: connecting as 'matchmaker' to 1.2.3.4    
2024-11-04T09:49:23.765512Z  INFO bevygap_shared: NATS: using self-signed CA: /Users/rj/Library/Application Support/mkcert/rootCA.pem    
2024-11-04T09:49:23.777111Z  INFO bevygap_shared: 🟢 NATS: connected OK    
2024-11-04T09:49:23.777121Z  INFO async_nats: event: connected
NATS connected OK!

If you made it this far, you've got a working NATS setup. Now on to the fun stuff.