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The request span was created at the ASGI edge, before anything knew which
route would match, so it carried nothing but the method: every request in a
trace UI showed up as "GET", and the only URL on it was url.path, which is
unbounded on a public instance and useless as a grouping key. Routing
resolves in DatasetteRouter, so that is where the span gets http.route and
its semconv `{method} {route}` name.
http.route is the compiled route pattern, not a prettified
/{database}/{table} template. Datasette routes with compiled regexes and the
route table is fixed when the app is built, so the pattern is exact, bounded
and needs no parsing; the transform into something prettier accretes edge
cases, and Django's instrumentation ships regex-flavoured routes for the same
reason. A request that matches no route gets no http.route and keeps its bare
method name, which is what semantic conventions ask for.
Two things the obvious implementation gets wrong, both found by testing it:
- The router must not read `get_current_span()`. A plugin asgi_wrapper()
runs *inside* the request middleware, so an instrumented plugin makes its
own span current for the whole request - and the route then lands on that
plugin's INTERNAL span, renaming it, while the actual request span never
gets the one attribute a trace UI groups by. It reproduces with a five-line
plugin. The span is passed through the ASGI scope instead, falling back to
the current span so an externally-created SERVER span is still enriched.
- The method has to be clamped again here. The middleware clamps it for the
attribute, but the name is rebuilt from request.method, which is the raw
client string - so an unclamped rename put `FROB /(?P<database>...` back
into the span name that the middleware had just kept it out of.
Both guards are `is_recording()`, not `get_span_context().is_valid`: with no
provider but an inbound traceparent the API returns a NonRecordingSpan
carrying the remote context, which is valid and records nothing, so an
is_valid guard would do the work on every request from a traced caller.
Tests cover the route and name, the unrouted 404 fallback, the full attribute
set, db.query spans reaching the request span by parent walk, a 500, an
inbound traceparent becoming a remote parent, ?sql= never reaching a span
attribute, and - in a subprocess, because the suite's provider fixture is
session-scoped and unavoidable - the no-provider fast path handing the app
the original `send`. The streaming test uses a table larger than one page so
the export genuinely issues queries during the body send; without that it
passes however early the span ends.
Measured on this branch against fixtures.db: a faceted table page went from
112 spans in 56 traces to 113 spans in 1.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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| .. | ||
| _static | ||
| _templates | ||
| .gitignore | ||
| authentication.rst | ||
| auto-build.sh | ||
| binary_data.rst | ||
| changelog.rst | ||
| cli-reference.rst | ||
| codespell-ignore-words.txt | ||
| conf.py | ||
| configuration.rst | ||
| contributing.rst | ||
| csv_export.rst | ||
| custom_templates.rst | ||
| datasette-0.51.png | ||
| datasette-logo.svg | ||
| deploying.rst | ||
| ecosystem.rst | ||
| events.md | ||
| facets.rst | ||
| full_text_search.rst | ||
| getting_started.rst | ||
| index.rst | ||
| installation.rst | ||
| internals.rst | ||
| introspection.rst | ||
| javascript_plugins.rst | ||
| json_api.rst | ||
| json_api_doc.py | ||
| Makefile | ||
| metadata.rst | ||
| metadata_doc.py | ||
| pages.rst | ||
| performance.rst | ||
| plugin_hooks.rst | ||
| plugins.rst | ||
| publish.rst | ||
| settings.rst | ||
| spatialite.rst | ||
| sql_queries.rst | ||
| telemetry_doc.py | ||
| template_context.rst | ||
| template_context_doc.py | ||
| testing_plugins.rst | ||
| upgrade-1.0a20.md | ||
| upgrade_guide.md | ||
| writing_plugins.rst | ||
