Add more data monitoring to gateways

[cambierr]

It could be great to add more monitoring fields to gateways. In our case, we are monitoring cpu load, ram % use, bandwidth, packet losses, and two temperatures.

This could be achieved by adding a repeated meta field which is a Key/Value pair for instance, so that custom monitoring is possible by adding fields in different gateways / forwarder implementations

[remyleone]

Would be good to add stats on:

• [ ] signal strengths and signal/noise ratios too
• [ ] activity
• [ ] rx/tx counters

[htdvisser]

We already have the following optional fields in stat messages:

• "pfrm":"Kerlink" - the gateway platform
• "mail":"contact@email.network" - contact info of the gateway owner
• "desc":"Contacts Home Gateway" - description of the gateway

It would be possible to add some system metrics to the packet_forwarder protocol like @cambierr suggests. We'd have to specify a set of "supported" fields (because sending arbitrary data is usually a bad idea):

• "load":"1.54 1.93 2.03" - system load of the gateway host
• "cpu":12 - average total CPU usage (in percent) since the last stat message
• "mem":12 - total memory usage (in percent)
• "temp":31.5 - temperature

The other statistics mentioned, can easily be determined on the server-side.

• RSSI/SNR is added to each uplink message
• Rx/Tx is already in the packet_forwarder protocol
• Activity can easily be measured by looking at the Uplink/Downlink that pass through the backend
• Bandwidth (at least to the backend) can be calculated by the backend

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Implementing the system metrics fields is not much work on the server side, and it sounds like @cambierr already implemented this for the packet forwarder. Let's try to formalize a specification for these fields (also the existing ones, because those are not really documented either).

[htdvisser]

The gateway.Status proto now contains the following fields:

float   load_1
float   load_5
float   load_15
float   cpu_percentage
float   memory_percentage
float   temperature

These fields will have to be filled by the gateway. If the gateway uses the ttn-gateway-connector this can be done by simply filling the protocol buffer. The packet_forwarder does not support these fields.