OpenTelemetry: Multiple problems sending telemetry to an endpoint

[Ionaru]

Using a fresh project and adding the required OpenTelemetry environment variables as described in https://usefresh.dev/docs/advanced/opentelemetry, shows no indication that OpenTelemetry is logging anything.

Summary of problems I found:

• OTEL_TRACES_EXPORTER variable name is incorrect, should be OTEL_EXPORTER_OTLP_PROTOCOL.
• Without OTEL_EXPORTER_OTLP_PROTOCOL=console, no metrics are sent to any endpoint.

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Repro using console:

1. Create a new project: deno run -Ar jsr:@fresh/init telemetry-test --tailwind false --vscode false
2. cd telemetry-test
3. deno task build
4. OTEL_DENO=true OTEL_TRACES_EXPORTER=console deno task start
5. Go to http://localhost:8000
6. Navigate around a bit
7. Notice no extra logging in the terminal

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Repro using Jaeger:

1. Create a new project: deno run -Ar jsr:@fresh/init telemetry-test --tailwind false --vscode false
2. Run Jaeger: docker run --rm --name jaeger -p 16686:16686 -p 4317:4317 -p 4318:4318 -p 5778:5778 -p 9411:9411 cr.jaegertracing.io/jaegertracing/jaeger:2.19.0
3. cd telemetry-test
4. deno task build
5. OTEL_DENO=true OTEL_EXPORTER_OTLP_ENDPOINT=http://localhost:4317 deno task start
6. Go to http://localhost:8000
7. Navigate around a bit
8. Go to http://localhost:16686
9. Notice that the service (as unknown_service is not listed, only Jaeger itself is listed (after F5)

Optionally check http://localhost:16686/api/v3/services to see if unknown_service is listed. That should be the Fresh application.

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One problem I managed to solve by comparing the Fresh and Deno docs is that the OTEL_TRACES_EXPORTER variable should be named OTEL_EXPORTER_OTLP_PROTOCOL

With that variable change, the console starts logging things, confirming that OpenTelemetry is doing something.

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NOTE:

After a lot of testing, I found that OTEL_DENO=true OTEL_EXPORTER_OTLP_PROTOCOL=console deno task start also sends data to the Jaeger endpoint. Without OTEL_EXPORTER_OTLP_PROTOCOL=console I have not been able to make that happen.

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deno 2.8.2 (stable, release, x86_64-unknown-linux-gnu)
v8 14.9.207.2-rusty
typescript 6.0.3