fix(tracing): establish tracing capture context early enough - #3057
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Rails::Rack::Logger's "Started ..." line (and anything logged before CaptureExceptions runs) got an unrelated trace_id, since CaptureExceptions runs after ActionDispatch::ShowExceptions. Add Sentry::Rails::CaptureContext, a minimal middleware unshifted to the front of the stack that establishes the propagation context early. CaptureExceptions now consumes and reuses it instead of regenerating a new trace_id/span_id. Co-Authored-By: GitHub Copilot <noreply@example.com>
This fixes the issue while ensuring we're not adding Sentry overhead to static file-serving routes, which is why the middleware was moved historically.
The established flag lived in the request-scoped env but certified a thread-local hub, so any middleware doing `@app.call` on another thread lost the incoming trace. The env now carries the context itself, trusted only while it is still the current scope's.
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| class TraceContextController < ActionController::Base | ||
| before_action :set_cors_headers | ||
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| def show | ||
| Sentry.logger.info("controller log", source: "controller") | ||
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| render json: { trace: Sentry.get_current_scope.get_trace_context } | ||
| end | ||
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| private | ||
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| def set_cors_headers | ||
| response.headers["Access-Control-Allow-Origin"] = "*" | ||
| response.headers["Access-Control-Allow-Methods"] = "GET, POST, PUT, DELETE, OPTIONS" | ||
| response.headers["Access-Control-Allow-Headers"] = "Content-Type, Authorization, sentry-trace, baggage" | ||
| end | ||
| end |
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This is based on #3016
This adds a new
Sentry::Rails::CaptureContextmiddleware establishes the propagation context once, early.CaptureExceptionsreuses it instead of generating its own, and a transaction with no incoming trace continues the established one rather than fabricating a newtrace_id.It sits
insert_after ActionDispatch::Executor- aboveRails::Rack::Loggerso the fix covers the logging, below the file-serving middlewares so static requests never touch Sentry.Fixes #3015