35 lines
1.3 KiB
Markdown
35 lines
1.3 KiB
Markdown
# Tracing
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Lotus has tracing built into many of its internals. To view the traces, first download [jaeger](https://www.jaegertracing.io/download/) (Choose the 'all-in-one' binary). Then run it somewhere, start up the lotus daemon, and open up localhost:16686 in your browser.
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## Open Census
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Lotus uses [OpenCensus](https://opencensus.io/) for tracing application flow.
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This generates spans
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through the execution of annotated code paths.
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Currently it is set up to use jaeger, though other tracing backends should be
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fairly easy to swap in.
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## Running Locally
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To easily run and view tracing locally, first, install jaeger. The easiest way
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to do this is to [download the binaries](https://www.jaegertracing.io/download/) and then run the `jaeger-all-in-one`
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binary. This will start up jaeger, listen for spans on `localhost:6831`, and
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expose a web UI for viewing traces on `http://localhost:16686/`.
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Now, to start sending traces from lotus to jaeger, set the environment variable
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`LOTUS_JAEGER` to `localhost:6831`, and start the `lotus daemon`.
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Now, to view any generated traces, open up `http://localhost:16686/` in your
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browser.
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## Adding Spans
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To annotate a new codepath with spans, add the following lines to the top of the function you wish to trace:
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```go
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ctx, span := trace.StartSpan(ctx, "put function name here")
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defer span.End()
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```
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