NATS Configuration

File Location

C:\Users\<username>\AppData\Local\OptionsRealTime\nats.config

Default Configuration

# NATS Server Configuration for OptionsRealTime
host: 127.0.0.1
port: 4222
http: 127.0.0.1:8222
max_payload: 67000000

jetstream {
  store_dir: "C:/Users/<username>/AppData/Local/OptionsRealTime/jetstream"
  max_memory_store: 1GB
  max_file_store: 50GB
  sync_interval: "2m"
}

Configuration Options

Network Settings

Setting	Default	Description
`host`	`127.0.0.1`	IP address to bind. Use `0.0.0.0` for multi-machine setups.
`port`	`4222`	Main NATS port for client connections
`http`	`127.0.0.1:8222`	HTTP monitoring endpoint
`max_payload`	`67000000`	Maximum message size in bytes (~64MB)

JetStream Settings

Setting	Default	Description
`store_dir`	`<install>/jetstream`	Absolute path to JetStream data storage
`max_memory_store`	`1GB`	Maximum memory for stream storage
`max_file_store`	`50GB`	Maximum disk space for stream storage
`sync_interval`	`2m`	How often to sync data to disk

Common Scenarios

Single Machine (Default)

No changes needed. The default 127.0.0.1 binding only allows local connections.

Multi-Machine Setup

See the Multi-Machine Setup guide for complete step-by-step instructions, including firewall configuration.

Increase Storage Limits

For larger historical data needs:

jetstream {
  max_memory_store: 2GB
  max_file_store: 100GB
}

Important Notes

Absolute paths required: The store_dir must be an absolute path (e.g., C:/Users/.../jetstream), not relative. This ensures consistent behavior whether NATS runs as a service or manually.
Forward slashes: Use forward slashes (/) in paths, not backslashes.
Config preserved on upgrade: The installer will not overwrite an existing nats.config. Your customizations are preserved.
Restart required: After editing nats.config, restart NATS:
- If running as service: Use Remove NATS Service then Install NATS Service (both as Administrator)
- If running manually: Close the NATS window and double-click Start NATS

Troubleshooting

Problem	Solution
Remote machine can’t connect	See Multi-Machine Setup — includes firewall fix
JetStream data not persisting	Verify `store_dir` is an absolute path
Out of disk space errors	Increase `max_file_store` or clear old streams
Service won’t start	Run Start NATS manually to see the error message