feat(active_job): support for tracing

[solnic]

This branch extends Sentry's ActiveJob instrumentation so distributed tracing works across Resque, DelayedJob, and Sidekiq. Instead of per-adapter integrations, tracing is now driven through a single common ActiveJob extension (Sentry::Rails::ActiveJobExtensions), which hooks serialize / deserialize / perform_now to:

• emit a producer span on enqueue,
• propagate trace context (and, with PII enabled, an allowlisted user context) through the job payload under a single _sentry key,
• record messaging span data on the consumer transaction,
• isolate the Sentry hub per worker thread.

Because the behavior lives in one extension, every adapter is verified against the same set of shared AJ specs — adding a new adapter is just a context + a one-line it_behaves_like.

New config

config.rails.active_job_propagate_traces (default true) gates trace propagation through the job payload.

New shared specs

A spec wires up the shared backend harness, an adapter-specific context, and the shared example groups.

Resque:

RSpec.describe "Sentry + ActiveJob on the resque adapter", type: :job do
  include ActiveSupport::Testing::TimeHelpers
  include_context "active_job backend harness", adapter: :resque
  include_context "resque adapter"

  it_behaves_like "a Sentry-instrumented ActiveJob backend"
  it_behaves_like "an ActiveJob backend that supports distributed tracing"
end

Sidekiq:

RSpec.describe "Sentry + ActiveJob on the sidekiq adapter", type: :job do
  include_context "active_job backend harness", adapter: :sidekiq
  include_context "sidekiq adapter"

  it_behaves_like "a Sentry-instrumented ActiveJob backend"
  it_behaves_like "an ActiveJob backend that supports distributed tracing"
end

The "...supports distributed tracing" shared example is itself a meta-group that pulls in the individual checks, so each adapter gets full coverage for free:

RSpec.shared_examples "an ActiveJob backend that supports distributed tracing" do
  it_behaves_like "an ActiveJob backend that emits a producer span on enqueue"
  it_behaves_like "an ActiveJob backend that propagates trace context through the job payload"
  it_behaves_like "an ActiveJob backend that records messaging span data on the consumer transaction"
  it_behaves_like "an ActiveJob backend that propagates Sentry user context through job payloads"
  it_behaves_like "an ActiveJob backend that isolates Sentry context per worker thread"
end

E2E coverage

This branch add more E2E specs (spec/features/active_job_tracing_spec.rb) that exercises the full path: the Svelte mini app's "Trigger Job" button fetches POST /jobs on the Rails mini app, the browser SDK propagates sentry-trace + baggage, and we assert that the browser fetch, the controller http.server transaction, the queue.publish producer span, and the queue.active_job consumer transaction all share one trace (consumer parented on the publish span, matching messaging.message.id).

To support worker-based adapters, spec/apps/rails-mini/worker.rb boots the same Rails + Sentry app in a separate process and runs the job through whichever adapter SENTRY_E2E_ACTIVE_JOB_ADAPTER selects (:async/:inline in-process, or a real worker for :sidekiq, :resque, :delayed_job) — so the same e2e assertions run across adapters via the CI matrix.

Screenshots

Distributed tracing works OOTB now with any Active Job adapter 🎉

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[dingsdax]

lgtm, I don't see any blockers