MQTT adapter

MQTT adapter provides an MQTT API for sending messages through the platform. MQTT adapter uses mProxy for proxying traffic between client and MQTT broker.

Configuration

The service is configured using the environment variables presented in the following table. Note that any unset variables will be replaced with their default values.

Variable	Description	Default
SMQ_MQTT_ADAPTER_LOG_LEVEL	Log level for the MQTT Adapter (debug, info, warn, error)	info
SMQ_MQTT_ADAPTER_MQTT_PORT	mProxy port	1883
SMQ_MQTT_ADAPTER_MQTT_TARGET_HOST	MQTT broker host	localhost
SMQ_MQTT_ADAPTER_MQTT_TARGET_PORT	MQTT broker port	1883
SMQ_MQTT_ADAPTER_MQTT_QOS	MQTT broker QoS	1
SMQ_MQTT_ADAPTER_FORWARDER_TIMEOUT	MQTT forwarder for multiprotocol communication timeout	30s
SMQ_MQTT_ADAPTER_MQTT_TARGET_HEALTH_CHECK	URL of broker health check	""
SMQ_MQTT_ADAPTER_WS_PORT	mProxy MQTT over WS port	8080
SMQ_MQTT_ADAPTER_WS_TARGET_HOST	MQTT broker host for MQTT over WS	localhost
SMQ_MQTT_ADAPTER_WS_TARGET_PORT	MQTT broker port for MQTT over WS	8080
SMQ_MQTT_ADAPTER_WS_TARGET_PATH	MQTT broker MQTT over WS path	/mqtt
SMQ_MQTT_ADAPTER_INSTANCE	Instance name for MQTT adapter	""
SMQ_CLIENTS_AUTH_GRPC_URL	Clients service Auth gRPC URL	localhost:7000
SMQ_CLIENTS_AUTH_GRPC_TIMEOUT	Clients service Auth gRPC request timeout in seconds	1s
SMQ_CLIENTS_AUTH_GRPC_CLIENT_CERT	Path to the PEM encoded clients service Auth gRPC client certificate file	""
SMQ_CLIENTS_AUTH_GRPC_CLIENT_KEY	Path to the PEM encoded clients service Auth gRPC client key file	""
SMQ_CLIENTS_AUTH_GRPC_SERVER_CERTS	Path to the PEM encoded clients server Auth gRPC server trusted CA certificate file	""
SMQ_ES_URL	Event sourcing URL	nats://localhost:4222
SMQ_MESSAGE_BROKER_URL	Message broker instance URL	nats://localhost:4222
SMQ_JAEGER_URL	Jaeger server URL	http://localhost:4318/v1/traces
SMQ_JAEGER_TRACE_RATIO	Jaeger sampling ratio	1.0
SMQ_SEND_TELEMETRY	Send telemetry to supermq call home server	true
SMQ_MQTT_ADAPTER_INSTANCE_ID	Service instance ID	""

Deployment

The service itself is distributed as Docker container. Check the mqtt-adapter service section in docker-compose file to see how service is deployed.

Running this service outside of container requires working instance of the message broker service, clients service and Jaeger server. To start the service outside of the container, execute the following shell script:

# download the latest version of the service
git clone https://github.com/absmach/supermq

cd supermq

# compile the mqtt
make mqtt

# copy binary to bin
make install

# set the environment variables and run the service
SMQ_MQTT_ADAPTER_LOG_LEVEL=info \
SMQ_MQTT_ADAPTER_MQTT_PORT=1883 \
SMQ_MQTT_ADAPTER_MQTT_TARGET_HOST=localhost \
SMQ_MQTT_ADAPTER_MQTT_TARGET_PORT=1883 \
SMQ_MQTT_ADAPTER_MQTT_QOS=1 \
SMQ_MQTT_ADAPTER_FORWARDER_TIMEOUT=30s \
SMQ_MQTT_ADAPTER_MQTT_TARGET_HEALTH_CHECK="" \
SMQ_MQTT_ADAPTER_WS_PORT=8080 \
SMQ_MQTT_ADAPTER_WS_TARGET_HOST=localhost \
SMQ_MQTT_ADAPTER_WS_TARGET_PORT=8080 \
SMQ_MQTT_ADAPTER_WS_TARGET_PATH=/mqtt \
SMQ_MQTT_ADAPTER_INSTANCE="" \
SMQ_CLIENTS_AUTH_GRPC_URL=localhost:7000 \
SMQ_CLIENTS_AUTH_GRPC_TIMEOUT=1s \
SMQ_CLIENTS_AUTH_GRPC_CLIENT_CERT="" \
SMQ_CLIENTS_AUTH_GRPC_CLIENT_KEY="" \
SMQ_CLIENTS_AUTH_GRPC_SERVER_CERTS="" \
SMQ_ES_URL=nats://localhost:4222 \
SMQ_MESSAGE_BROKER_URL=nats://localhost:4222 \
SMQ_JAEGER_URL=http://localhost:14268/api/traces \
SMQ_JAEGER_TRACE_RATIO=1.0 \
SMQ_SEND_TELEMETRY=true \
SMQ_MQTT_ADAPTER_INSTANCE_ID="" \
$GOBIN/supermq-mqtt

Setting SMQ_CLIENTS_AUTH_GRPC_CLIENT_CERT and SMQ_CLIENTS_AUTH_GRPC_CLIENT_KEY will enable TLS against the clients service. The service expects a file in PEM format for both the certificate and the key. Setting SMQ_CLIENTS_AUTH_GRPC_SERVER_CERTS will enable TLS against the clients service trusting only those CAs that are provided. The service expects a file in PEM format of trusted CAs.

For more information about service capabilities and its usage, please check out the API documentation API.