The Microbus framework uses environment variables for various purposes:
PROD, LAB, LOCAL, TESTING)Environment variables may also be set by placing an env.yaml file in the working directory of the executable running the microservice. The bundled example application includes such a file at main/env.yaml.
A microservice can’t communicate with other microservices, including the configurator microservice, before connecting to the transport. Initializing the NATS connection therefore relies on environment variables: MICROBUS_NATS, MICROBUS_NATS_USER, MICROBUS_NATS_PASSWORD and MICROBUS_NATS_TOKEN.
MICROBUS_SHORT_CIRCUIT can be set to 0 or false to disable the short-circuit transport.
The MICROBUS_DEPLOYMENT environment variable determines the deployment environment of the microservice: PROD, LAB, LOCAL or TESTING. If not specified, PROD is assumed, unless connecting to nats://localhost:4222 or nats://127.0.0.1:4222 in which case LOCAL is assumed.
The plane of communication is a unique prefix set for all communications sent or received over NATS. It is used to isolate communication among a group of microservices over a NATS cluster that is shared with other microservices.
If not explicitly set via the SetPlane method of the Connector, the value is pulled from the MICROBUS_PLANE environment variable. The plane must include only alphanumeric characters and is case-sensitive.
Applications created with application.NewTesting set a random plane to eliminate the chance of collision when tests are executed in parallel in the same NATS cluster, e.g. using go test ./... -p=8.
This is an advanced feature and in most cases there is no need to customize the plane of communications.
The MICROBUS_LOCALITY environment variable sets the locality of the microservice, which is used as the basis for locality-aware routing.
Setting the MICROBUS_LOG_DEBUG environment variable to 1 or true is required for microservices to log debug-level messages.
Microbus pushes telemetry to Grafana via its OpenTelemetry collector. The endpoint of the collector is configured using the OTEL_EXPORTER_OTLP_TRACES_ENDPOINT, OTEL_EXPORTER_OTLP_METRICS_ENDPOINT or OTEL_EXPORTER_OTLP_ENDPOINT environment variables.
The OTEL_METRIC_EXPORT_INTERVAL variable can be used to set the interval (in milliseconds) between pushes of metrics. It defaults to 15 seconds in LOCAL or TESTING deployments, and 60 seconds in PROD or LAB deployments.
Other OpenTelemetry environment variables are respected.
Set the MICROBUS_PROMETHEUS_EXPORTER variable to 1 or true to enable Prometheus metric collection in the microservice. This enables the metrics core microservice to collect and aggregate metrics from the microservice.