NATS is the communication medium of microservices and all microservices must first and foremost be connected to NATS in order to send and receive messages. By default, microservices attempt to connect to NATS on nats://127.0.0.1:4222 using a plain (unsecure) TCP connection. The MICROBUS_NATS environment variable is used to customize this connection URL.
NATS supports various authentication methods for connecting to the NATS cluster. The Microbus framework is exposing some of these via environment variables and certificate files.
The MICROBUS_NATS_USER and MICROBUS_NATS_PASSWORD environment variables, when present, are used to authenticate with simple username and password credentials.
The MICROBUS_NATS_TOKEN environment variable, when present, is used to authenticate with an API token credential.
NATS needs a public certificate and a private key in order to secure the connection to NATS with TLS. Microbus looks for the certs in the current working directory under the names cert.pem and key.pem.
A root certificate authority (CA) certificate may be required by NATS to trust other certificates. Microbus looks for the CA certificate file in the current working directory under the name ca.pem.