elastic: Add traced HTTPClient for client #68
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conorbranagan
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I should mention that there wasn't a way to directly hook into the |
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| // Package elastictraced provides tracing for the Elastic Elasticsearch client (https://github.com/olivere/elastic) | |||
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Are we compatible only with v5?
We should explicit the compatible versions in the doc (and if that's more than v5, we should also add the others in the tests).
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| // pathIsTraced returns a boolean indicating if a given Elasticsearch path |
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What was the reasons behind these rules?
- I guess it is legit to get stats on health checks/internal checks? Are apps really going to hit these endpoints anyway?
- while we can't get much metadata, bulk requests can represent most of the operations for some workers?
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- The health check was coming from the elastic library itself, on startup. But fair, I can leave it in.
- My concern on bulk was adding overhead when reading the body but maybe we can not read it if it's greater than some size. I'll look into this.
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- Oh, I didn't know about this internal! When you say startup, it is the initial connection? After the first query? If that's spammy or outside of the context of a real traced transaction, I'm good with skipping it. Otherwise, it is good to see what's really happening during the traced code.
- Oh, good concern. From what I recalled, we even internally forked this client to avoid this expensive operation. If I recall well, the hack was to read it manually, the "error" was at the beginning of the Body so we were able to find it for cheap by just looking at the beginning of the body.
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| res.Body = ioutil.NopCloser(bytes.NewBuffer(buf)) | ||
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| span.SetMetric(ext.HTTPCode, float64(res.StatusCode)) |
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This might be a number, it is more legit to see it as a "code" ie. using SetMeta. "Metric" were more for graphable values (but we aren't sure we will keep that in the future).
| res, err := t.Transport.RoundTrip(req) | ||
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| if err != nil { | ||
| span.SetError(err) |
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Would res.StatusCode be available here? Would be nice to set it as a meta too.
TracedHTTPClient hooks into the http.Transport to trace requests and capture spans for Elasticsearch. It's generic enough that it could be used for other Elasticsearch clients that allow you to override the http client. The tests and example show the pattern for tracing the elastic client, specifically using elastic.v5. Older versions do not support calling `Do` with a context so they won't apply. But in theory this should be compatible with new version going forward. docker-compose is updated to run ES for the integration tests.
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TracedHTTPClient hooks into the http.Transport to trace requests and
capture spans for Elasticsearch. It's generic enough that it could be
used for other Elasticsearch clients that allow you to override the http
client.
The resource is quantized following the style used in dd-trace-py
The tests and example show the pattern for tracing the elastic client,
specifically using elastic.v5. Older versions do not support calling
Dowith acontextso they won't apply. But in theory this should becompatible with new version going forward.
docker-compose is updated to run ES for the integration tests.