(fix) Header propagation rule passthrough

[BrynCooke]

Header propagation contains logic to prevent headers from being propagated more than once. This was broken in #6281 which always considered a header propagated regardless if a rule actually matched.

This PR alters the logic so that only when a header is populated then the header is marked as fixed.

The following will now work again:

headers:
  all:
    request:
      - propagate:
          named: a
          rename: b
      - propagate:
          named: b

Note that defaulting a head WILL populate a header, so make sure to include your defaults last in your propagation rules.

headers:
  all:
    request:
      - propagate:
          named: a
          rename: b
          default: defaulted # This will prevent any further rule evaluation for header `b`
      - propagate:
          named: b

Instead make sure that your headers are defaulted last:

headers:
  all:
    request:
      - propagate:
          named: a
          rename: b
      - propagate:
          named: b
          default: defaulted # OK

---

Checklist

Complete the checklist (and note appropriate exceptions) before the PR is marked ready-for-review.

• Changes are compatible¹
• Documentation² completed
• Performance impact assessed and acceptable
• Tests added and passing³
  • Unit Tests
  • Integration Tests
  • Manual Tests

Exceptions

Note any exceptions here

Notes

Footnotes

1. It may be appropriate to bring upcoming changes to the attention of other (impacted) groups. Please endeavour to do this before seeking PR approval. The mechanism for doing this will vary considerably, so use your judgement as to how and when to do this. ↩

2. Configuration is an important part of many changes. Where applicable please try to document configuration examples. ↩

3. Tick whichever testing boxes are applicable. If you are adding Manual Tests, please document the manual testing (extensively) in the Exceptions. ↩

[svc-apollo-docs]

✅ Docs preview has no changes

The preview was not built because there were no changes.

Build ID: af85560a491445f7fd6c9c07

[goto-bus-stop]

subtle... should we also clarify in the docs that you should put items with default last?

[BrynCooke]

subtle... should we also clarify in the docs that you should put items with default last?
Good point I'll add it.

[BrynCooke]

Docs updated: c7c0969

[BrynCooke]

Tests needed refactoring: 7b129df. Code is cleaner now.

[BrynCooke]

@mergify queue

[mergify]

queue

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[BrynCooke]

@shorgi I've made some docs changes so it'd be great if you could take a pass.

[router-perf]

CI performance tests

• connectors-const - Connectors stress test that runs with a constant number of users
• const - Basic stress test that runs with a constant number of users
• demand-control-instrumented - A copy of the step test, but with demand control monitoring and metrics enabled
• demand-control-uninstrumented - A copy of the step test, but with demand control monitoring enabled
• enhanced-signature - Enhanced signature enabled
• events - Stress test for events with a lot of users and deduplication ENABLED
• events_big_cap_high_rate - Stress test for events with a lot of users, deduplication enabled and high rate event with a big queue capacity
• events_big_cap_high_rate_callback - Stress test for events with a lot of users, deduplication enabled and high rate event with a big queue capacity using callback mode
• events_callback - Stress test for events with a lot of users and deduplication ENABLED in callback mode
• events_without_dedup - Stress test for events with a lot of users and deduplication DISABLED
• events_without_dedup_callback - Stress test for events with a lot of users and deduplication DISABLED using callback mode
• extended-reference-mode - Extended reference mode enabled
• large-request - Stress test with a 1 MB request payload
• no-tracing - Basic stress test, no tracing
• reload - Reload test over a long period of time at a constant rate of users
• step-jemalloc-tuning - Clone of the basic stress test for jemalloc tuning
• step-local-metrics - Field stats that are generated from the router rather than FTV1
• step-with-prometheus - A copy of the step test with the Prometheus metrics exporter enabled
• step - Basic stress test that steps up the number of users over time
• xlarge-request - Stress test with 10 MB request payload
• xxlarge-request - Stress test with 100 MB request payload