Add additional Prebid debug flags to OpenRTB requests by ChristianPavilonis · Pull Request #377 · IABTechLab/trusted-server

ChristianPavilonis · 2026-02-25T20:46:20Z

Summary

Adds debug diagnostics to Prebid/OpenRTB bid requests, surfaces Prebid Server debug response data in the /auction endpoint response, and forwards the real client IP to PBS so bidders see residential rather than data-center traffic.

Changes

New `test_mode` config param (`prebid.rs`, config)

Added a separate test_mode config flag that controls the OpenRTB test: 1 field independently from debug. This is intentionally separate because test: 1 signals non-billable traffic and bidders like PubMatic heavily throttle fill (~10% vs ~100%). Defaults to false.

debug: true — enables ext.prebid.debug, ext.prebid.returnallbidstatus, debug response metadata, and debug logging
test_mode: true — sets test: 1 in the OpenRTB request (defaults to false)

Forward real client IP in `device.ip` (`openrtb.rs`, `prebid.rs`)

Added ip field to the OpenRTB Device struct, populated from DeviceInfo.ip (the real client IP from get_client_ip_addr()). Without this, PBS infers the IP from the incoming connection — a Fastly edge/data-center IP — causing bidders to filter the traffic as non-human (0% fill through Trusted Server).

OpenRTB request debug flags (`openrtb.rs`, `prebid.rs`)

When config.debug is enabled, the outgoing OpenRTB request now includes:

{
  "ext": {
    "prebid": {
      "debug": true,
      "returnallbidstatus": true
    }
  }
}

ext.prebid.debug: true — enables Prebid Server debug output (httpcalls, resolvedrequest)
ext.prebid.returnallbidstatus: true — includes all bid statuses (rejected/no-bid reasons) in the response

All fields are omitted from serialization when debug is disabled (default).

Response debug logging (`prebid.rs`)

Added log::debug! of the full Prebid Server response JSON in parse_response(), gated on both config.debug and log::log_enabled!(Level::Debug) to avoid wasted serialization.

Debug data in `/auction` response (`prebid.rs`)

Extracted enrich_response_metadata() method that attaches Prebid Server response metadata to AuctionResponse.metadata, which flows through ProviderSummary → provider_details in the /auction response ext:

Always-on fields (present whenever PBS returns them):

responsetimemillis — per-bidder response times
errors — per-bidder errors
warnings — per-bidder warnings (new)

Debug-gated fields (only when config.debug is true):

debug — full ext.debug blob (httpcalls, resolvedrequest)
bidstatus — per-bid status array from ext.prebid.bidstatus

Safety

Startup log::warn! emitted when debug: true is configured, alerting operators that debug data will be included in /auction responses
All debug fields default to None/omitted — no behavior change when debug is disabled

Tests

to_openrtb_includes_debug_flags_when_enabled — verifies debug flags set without test:1
to_openrtb_sets_test_flag_when_test_mode_enabled — verifies test:1 only with test_mode
to_openrtb_omits_debug_flags_when_disabled — verifies fields are None and omitted from JSON
enrich_response_metadata_attaches_always_on_fields — verifies always-on metadata present, debug-gated fields absent
enrich_response_metadata_includes_debug_fields_when_enabled — verifies debug + bidstatus present with correct values

ChristianPavilonis · 2026-02-25T21:43:35Z

Do we want this in the /auction response, or are debug logs good?
The no bids don't tell us a lot (no headers or anything comes back)

aram356 · 2026-02-26T16:30:02Z

Let's return response if prebid integration is enabled with debug = true

…bid OpenRTB requests

…n response metadata

…se_metadata with tests

PubMatic (and likely other bidders) heavily throttle fill on test:1 traffic (~10% vs ~100%). Previously debug=true set test:1, debug ext fields, and returnallbidstatus together. Now test:1 is controlled by a separate test_mode config param so debug diagnostics can be enabled in production without killing fill rates.

Without this, PBS infers the IP from the incoming connection which is a Fastly edge/data-center IP. Bidders like PubMatic filter data-center IPs as non-human traffic, resulting in 0% fill through Trusted Server. The client IP is already available via get_client_ip_addr() and stored in DeviceInfo.ip — it just wasn't being passed through to the OpenRTB Device object.

ChristianPavilonis · 2026-02-26T23:38:00Z

Investigation: PubMatic no-bid root causes

Debugged why PubMatic was returning 204 (no-bid) on every request through Trusted Server. Found two independent issues:

Issue 1: `test: 1` suppresses bidder demand

The debug: true config was setting test: 1 in the OpenRTB request, which signals non-billable test traffic. Tested fill rates by curling PBS directly with identical requests:

Condition	PubMatic Fill Rate
Without `test: 1`	10/10 (100%)
With `test: 1`	1/10 (10%)

Fix: Decoupled test: 1 into a separate test_mode config param (commit 19c7feb). debug: true still enables ext.prebid.debug and returnallbidstatus for diagnostics.

Issue 2: Fastly edge IP forwarded instead of real client IP

After removing test: 1, PubMatic was still returning 204 through the staging Fastly server (0/10). The OpenRTB Device struct didn't include an ip field, so PBS inferred the IP from the incoming connection — a Fastly data-center IP (157.52.114.28). PubMatic filters data-center IPs as non-human traffic.

The real client IP was already captured in DeviceInfo.ip via get_client_ip_addr() — it just wasn't being passed through to the OpenRTB request.

Fix: Added ip field to the OpenRTB Device struct (commit cb0486f).

Verified on staging

After deploying both fixes to the staging Fastly instance (167.82.82.98):

run 1:  {"pm_status":200,"pm_ip":"104.12.33.82","bidders":["mocktioneer","pubmatic"]}
run 2:  {"pm_status":204,"pm_ip":"104.12.33.82","bidders":["kargo","mocktioneer"]}
run 3:  {"pm_status":200,"pm_ip":"104.12.33.82","bidders":["mocktioneer","pubmatic"]}
run 4:  {"pm_status":204,"pm_ip":"104.12.33.82","bidders":["mocktioneer"]}
run 5:  {"pm_status":200,"pm_ip":"104.12.33.82","bidders":["mocktioneer","pubmatic"]}
run 6:  {"pm_status":200,"pm_ip":"104.12.33.82","bidders":["kargo","mocktioneer","pubmatic"]}
run 7:  {"pm_status":200,"pm_ip":"104.12.33.82","bidders":["mocktioneer","pubmatic"]}
run 8:  {"pm_status":200,"pm_ip":"104.12.33.82","bidders":["mocktioneer","pubmatic"]}
run 9:  {"pm_status":200,"pm_ip":"104.12.33.82","bidders":["mocktioneer","pubmatic"]}
run 10: {"pm_status":200,"pm_ip":"104.12.33.82","bidders":["kargo","mocktioneer","pubmatic"]}

PubMatic fill: 8/10 (80%), up from 0%. Real client IP (104.12.33.82) correctly forwarded in device.ip. Kargo also started bidding.

Additional finding: PubMatic only bids on 300x250

Tested all size combinations against PBS directly. PubMatic adSlot 4407979 (publisher 156229) only has demand for 300x250:

Sizes	Fill
970x90, 728x90, 970x250 (header only)	0/5 (0%)
300x250 only	4/5 (80%)
300x250 + 728x90 + 970x90 + 970x250 (in_content)	3/5 (60%)

The header ad slot will never get PubMatic bids since it doesn't include 300x250. This is a PubMatic-side slot configuration issue, not a Trusted Server bug.

ChristianPavilonis self-assigned this Feb 25, 2026

ChristianPavilonis requested review from aram356 and removed request for aram356 February 25, 2026 21:14

ChristianPavilonis marked this pull request as draft February 25, 2026 21:23

ChristianPavilonis added 3 commits February 26, 2026 13:10

Add test, returnallbidstatus, and response logging debug flags to Pre…

62630dd

…bid OpenRTB requests

Add tests for Prebid debug OpenRTB flags

8e58450

Surface Prebid debug data (httpcalls, bidstatus, warnings) in /auctio…

3d752dc

…n response metadata

ChristianPavilonis force-pushed the feature/additional-prebid-debug-flags branch from f204475 to 3d752dc Compare February 26, 2026 20:40

Address review: add log guard, startup warning, extract enrich_respon…

4cabee5

…se_metadata with tests

ChristianPavilonis marked this pull request as ready for review February 26, 2026 20:59

ChristianPavilonis requested review from aram356 and prk-Jr February 26, 2026 20:59

ChristianPavilonis added 2 commits February 26, 2026 17:19

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Add additional Prebid debug flags to OpenRTB requests#377

Add additional Prebid debug flags to OpenRTB requests#377
ChristianPavilonis wants to merge 6 commits intomainfrom
feature/additional-prebid-debug-flags

ChristianPavilonis commented Feb 25, 2026 •

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ChristianPavilonis commented Feb 25, 2026

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aram356 commented Feb 26, 2026

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ChristianPavilonis commented Feb 25, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Summary

Changes

New test_mode config param (prebid.rs, config)

Forward real client IP in device.ip (openrtb.rs, prebid.rs)

OpenRTB request debug flags (openrtb.rs, prebid.rs)

Response debug logging (prebid.rs)

Debug data in /auction response (prebid.rs)

Safety

Tests

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ChristianPavilonis commented Feb 25, 2026

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aram356 commented Feb 26, 2026

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ChristianPavilonis commented Feb 26, 2026

Investigation: PubMatic no-bid root causes

Issue 1: test: 1 suppresses bidder demand

Issue 2: Fastly edge IP forwarded instead of real client IP

Verified on staging

Additional finding: PubMatic only bids on 300x250

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ChristianPavilonis commented Feb 25, 2026 •

edited

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New `test_mode` config param (`prebid.rs`, config)

Forward real client IP in `device.ip` (`openrtb.rs`, `prebid.rs`)

OpenRTB request debug flags (`openrtb.rs`, `prebid.rs`)

Response debug logging (`prebid.rs`)

Debug data in `/auction` response (`prebid.rs`)

Issue 1: `test: 1` suppresses bidder demand