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chirpstack / chirpstack-gateway-bridge

ChirpStack Gateway Bridge abstracts Packet Forwarder protocols into Protobuf or JSON over MQTT.
https://www.chirpstack.io
MIT License
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LWT message support #117

Closed alexbondarchuk closed 3 years ago

alexbondarchuk commented 5 years ago

Is this a bug or a feature request?

Feature request

What d you expect?

Add following possibilities: 

        WillEnabled             bool
    WillTopic               string
    WillPayload             []byte
    WillQos                 byte
    WillRetained            bool

to lora-gateway-bridge config file for enable LWT feature. This options supported by paho.mqtt.golang client.

4refr0nt commented 5 years ago

This feature may be very useful for gateways monitoring

brocaar commented 4 years ago

I did see @sa-wilson his pull-request and I have been thinking about this feature for a while but I'm not sure if the ChirpStack Gateway Bridge should support this. As I understand, a LWT payload is usually used in the following way:

When an other MQTT client subscribes to device/123/status, it will receive online when the device is online, or offline when it disconnected.

The "issue" with the ChirpStack Gateway Bridge: when it starts, it has no knowledge which gateway(s) it is serving. Also, it is possible to connect multiple Packet Forwarder instances to a single Gateway Bridge. Ideally you would have a gateway/0102030405060708/status or gateway/0102030405060708/event/status LWT topic, but this is not possible as far as I know.

I would really like to avoid to add this as a fully generic function where the end-user in charge of all the parameters, including the configuration of the (potential binary) payload. This makes it really hard if not impossible to later integrate this with the other components.

I think a better way of gateway monitoring is to use the Prometheus metrics that the Gateway Bridge provides. Also, since most Packet Forwarder instances are configured to post stats every 30 seconds, you will see a gateway/GATEWAYID/event/stats message. This "heartbeat" can also be used for monitoring.

See also #85

brocaar commented 3 years ago

Please see https://www.chirpstack.io/gateway-bridge/changelog/#v3110 (Connection state messages).