See #132. This PR adds a protocol field to the ClientTransport and ServerTransport messages, and modifies the proxy to report a value for this field (currently, it's only ever HTTP).
Currently, HTTP/1 and HTTP/2 are collapsed into one Protocol variant, see #132 (comment). I expect that we can treat H1 as a subset of H2 as far as metrics goes.
Note that after discussing it with @klingerf, I learned that the control plane telemetry API currently does not do anything with the ClientTransport and ServerTransport messages, so beyond regenerating the protobuf-generated code, no controller changes were actually necessary. As we actually add metrics to TCP transports, we'll want to make some additions to the telemetry API to ingest these metrics. If any metrics are shared between HTTP and raw TCP transports (say, bytes sent), we'll want to differentiate between them in Prometheus. All the metrics that the control plane currently ingests from telemetry reports are likely to be HTTP-specific (requests, responses, response latencies), or at least, do not apply to raw TCP.
Actually adding metrics to raw TCP transports will probably have to wait until there are raw TCP transports implemented in the proxy...
Signed-off-by: Eliza Weisman <eliza@buoyant.io>
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