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 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

refactor + breaking changes

Eliminate custom OTEL in favor of standard vars.

before	after	notes
--telemetry-endpoint flag	OTEL_EXPORTER_OTLP_ENDPOINT	Required to enable telemetry
CUSTOM_OTLP_ENDPOINT	OTEL_EXPORTER_OTLP_ENDPOINT	Same var covers both cases
Auto-detected HTTP via non-443 port	OTEL_EXPORTER_OTLP_INSECURE=true	Only needed for plain HTTP endpoints
Hardcoded lantern-box service name	OTEL_SERVICE_NAME	Optional override, defaults to lantern-box
-	OTEL_RESOURCE_ATTRIBUTES	Optional extra attributes beyond .ini file

docker test dependency

Addition of "e2e" tests use docker and testcontainers to simulate all parts: client, singbox, otel, and upstream. Bypass with -short flag:
go test ./... -short

semconv

Using standard KVs for otel, with updates getlantern/semconv@121098b

[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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[jay-418]

Hey @garmr-ulfr, do you mind looking at this? The CLIENTINFO stuff is a little foreign to me, but running ping.sh with a running lantern-box does send the right trace with attrs to the local collector.

For context, this is my first draft adding spans to lantern-box for the purpose of better success/failure tracking after config assignment:

• https://github.com/getlantern/engineering/issues/2987

It's been suggested this entire approach could be supplanted by using the strategy laid out in:

• https://github.com/getlantern/lantern-cloud/pull/2261

[garmr-ulfr]

Besides ping.sh, LGTM. You implemented it correctly, but your test script is wrong.

[Crosse]

My only concern is that I believe we need to drop a bunch of our OTel configuration complexity and just use the built-in environment variables.

[jay-418]

My only concern is that I believe we need to drop a bunch of our OTel configuration complexity and just use the built-in environment variables.

@Crosse sorry I missed it the first time you said this. Will address today.

[Crosse]

@jay-418 You didn't miss anything—I never hit Send on the review last week.

[Copilot]

Pull request overview

Copilot reviewed 13 out of 15 changed files in this pull request and generated 7 comments.

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[garmr-ulfr]

@jay-418 I'm not sure I've mentioned this yet, but just FYI in case you weren't aware, lantern-box must be usable by anyone, so any changes shouldn't restrict it to Lantern. Not that you have, just a heads up 😄

[jay-418]

@jay-418 I'm not sure I've mentioned this yet, but just FYI in case you weren't aware, lantern-box must be usable by anyone, so any changes shouldn't restrict it to Lantern. Not that you have, just a heads up 😄

Sure thing @garmr-ulfr. I just completed some heavier handed changes, but they make everything more generic by using the standard OTEL convetions for env vars.

[garmr-ulfr]

LGTM! This will also require an update in lantern-cloud to use the --proxy-info flag once this is merged and deployed.