implement span for device_id.connected

[jay-418]

purpose

Provide mechanism for recording a device_id's first connection to a route to provide an indication of poor network conditions.

mechanism

Emit a span with device_id (and some attrs) when a proxy is assigned by the API during config request. Then also emit a span (here, this code) when a device_id first connects to a proxy.

In SigNoz, we can calculate (using some kinda gnarly ClickHouse queries as discussed in https://github.com/getlantern/engineering/issues/2987):

• the percentage of api config requests that never result in a proxy connections
• the latency between config request and initial proxy connection

[Copilot]

Pull request overview

Adds OpenTelemetry tracing to correlate a device’s proxy assignment with its first observed proxy connection, enabling connectivity success-rate and time-to-connect analysis in SigNoz.

Changes:

• Emit a device_id.connected span when CLIENTINFO is received on routed TCP/packet connections.
• Add OTLP/HTTP trace exporter initialization alongside existing metrics exporter initialization.
• Wire clientcontext manager into the run path by default and add a local ping script / Makefile flag plumbing.

Reviewed changes

Copilot reviewed 7 out of 9 changed files in this pull request and generated 7 comments.

Show a summary per file

File	Description
tracker/clientcontext/manager.go	Emits device_id.connected span with client attributes on successful CLIENTINFO parsing.
otel/otel.go	Adds InitGlobalTracerProvider using OTLP/HTTP exporter and SDK tracer provider.
cmd/main.go	Initializes global meter + tracer providers during CLI pre-run when proxy info is available.
cmd/cmd_run.go	Always registers the clientcontext manager (previously conditional) to enable tracing.
cmd/Makefile	Passes --telemetry-endpoint through make run.
scripts/ping.sh	Adds a script intended to exercise CLIENTINFO and produce the new span.
go.mod / go.sum	Adds OTLP trace HTTP exporter dependencies.
.gitignore	Ignores cmd/cmd.

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[Copilot]

This script won’t trigger the CLIENTINFO handling / device_id.connected span as written: the server-side Manager expects the first bytes on the connection to start with the CLIENTINFO prefix. Sending an HTTP CONNECT request first means the Manager will treat the connection as non-CLIENTINFO and the later CLIENTINFO ... bytes will just be forwarded as normal payload. Also, the CONNECT request line terminator looks incomplete (\r\n\r instead of \r\n\r\n). Consider sending the CLIENTINFO {...} packet first and reading the OK response (or otherwise matching the actual injector protocol) so this is a reliable test.