feat: support OpenTelemetry Metrics #3487

rachelyangdog · 2025-11-13T20:56:45Z

Description

Adds support for OpenTelemetry Metrics integration with Datadog.

Changes:

Added new configurations DD_METRICS_OTEL_ENABLED (enable OTel metrics support) and DD_HOSTNAME
Added OTel endpoint configuration according to the OTel Metrics RFC
Sets default metrics temporality to "delta" (according to RFC
Added auto configuring of OTLP endpoints using DD_TRACE_AGENT_URL and/or DD_AGENT_HOST
Added gRPC and HTTP protocol and port selection
Added resource attribute mapping
Added functions to support collection of telemetry metrics for configuration (actual implementation will be added in a separate PR)

Please refer to this document containing known discrepancies of the PHP OTel Metrics implementation

Reviewer checklist

Test coverage seems ok.
Appropriate labels assigned.

codecov-commenter · 2025-11-13T21:25:17Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 61.65%. Comparing base (14dc0a4) to head (0670208).
⚠️ Report is 4 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3487      +/-   ##
==========================================
- Coverage   61.73%   61.65%   -0.08%     
==========================================
  Files         143      143              
  Lines       13015    13015              
  Branches     1702     1702              
==========================================
- Hits         8035     8025      -10     
- Misses       4221     4228       +7     
- Partials      759      762       +3

see 4 files with indirect coverage changes

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pr-commenter · 2025-11-17T16:46:55Z

Benchmarks [ tracer ]

Benchmark execution time: 2025-12-15 21:08:34

Comparing candidate commit 0670208 in PR branch rachel.yang/otel-metrics-part2-telemetry with baseline commit 14dc0a4 in branch master.

Found 4 performance improvements and 15 performance regressions! Performance is the same for 175 metrics, 0 unstable metrics.

scenario:ComposerTelemetryBench/benchTelemetryParsing-opcache

🟥 execution_time [+0.498µs; +1.702µs] or [+3.888%; +13.299%]

scenario:ContextPropagationBench/benchExtractHeaders128Bit-opcache

🟥 execution_time [+787.688ns; +820.312ns] or [+90.400%; +94.145%]

scenario:ContextPropagationBench/benchExtractTraceContext64Bit-opcache

🟥 execution_time [+837.449ns; +920.551ns] or [+95.490%; +104.966%]

scenario:ContextPropagationBench/benchInject128Bit-opcache

🟥 execution_time [+749.412ns; +810.588ns] or [+44.555%; +48.192%]

scenario:HookBench/benchWithoutHook-opcache

🟩 execution_time [-5.680µs; -4.900µs] or [-10.207%; -8.807%]

scenario:LogsInjectionBench/benchLogsNullBaseline-opcache

🟩 execution_time [-1.318µs; -1.116µs] or [-6.006%; -5.089%]

scenario:LogsInjectionBench/benchLogsNullInjection-opcache

🟩 execution_time [-1.250µs; -1.140µs] or [-5.717%; -5.213%]

scenario:MessagePackSerializationBench/benchMessagePackSerialization

🟥 execution_time [+4.299µs; +5.381µs] or [+4.179%; +5.230%]

scenario:MessagePackSerializationBench/benchMessagePackSerialization-opcache

🟥 execution_time [+8.812µs; +11.328µs] or [+8.402%; +10.801%]

scenario:SamplingRuleMatchingBench/benchRegexMatching1

🟥 execution_time [+102.282ns; +135.318ns] or [+8.937%; +11.823%]

scenario:SamplingRuleMatchingBench/benchRegexMatching2

🟥 execution_time [+83.559ns; +126.841ns] or [+7.182%; +10.903%]

scenario:SamplingRuleMatchingBench/benchRegexMatching3

🟥 execution_time [+82.083ns; +133.917ns] or [+7.084%; +11.557%]

scenario:SamplingRuleMatchingBench/benchRegexMatching4

🟥 execution_time [+104.623ns; +153.177ns] or [+9.083%; +13.299%]

scenario:SpanBench/benchOpenTelemetryAPI

🟥 mem_peak [+1.773MB; +1.778MB] or [+4.293%; +4.305%]

scenario:SpanBench/benchOpenTelemetryAPI-opcache

🟥 mem_peak [+1.747MB; +1.750MB] or [+4.543%; +4.551%]

scenario:TraceSerializationBench/benchSerializeTrace

🟩 execution_time [-30.487µs; -12.813µs] or [-6.817%; -2.865%]

scenario:WordPressBench/benchWordPressBaseline-opcache

🟥 mem_peak [+150.424KB; +150.424KB] or [+3.137%; +3.137%]

scenario:WordPressBench/benchWordPressDdprof-opcache

🟥 mem_peak [+150.424KB; +150.424KB] or [+3.137%; +3.137%]

scenario:WordPressBench/benchWordPressOverhead-opcache

🟥 mem_peak [+150.424KB; +150.424KB] or [+3.137%; +3.137%]

PROFeNoM · 2025-12-09T09:17:04Z

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chatgpt-codex-connector · 2025-12-09T09:21:30Z

src/DDTrace/OpenTelemetry/Detectors/Host.php

+        if (\dd_trace_env_config('DD_TRACE_REPORT_HOSTNAME')) {
+            $attributes['host.name'] = \dd_trace_env_config('DD_HOSTNAME');
+        }


Avoid overriding host.name with empty DD_HOSTNAME

When DD_TRACE_REPORT_HOSTNAME is true but DD_HOSTNAME is unset, this hook always adds a host.name attribute with an empty string before calling ResourceInfo::merge. In OpenTelemetry, merge gives precedence to the attributes of the resource being merged in, so this empty value will overwrite the hostname the upstream Host detector already populated. The result is that OTel metrics exported with hostname reporting enabled lose the actual hostname and carry a blank host.name. Skip setting the attribute when DD_HOSTNAME is empty or fall back to the detected hostname to avoid clobbering the original value.

Useful? React with 👍 / 👎.

src/DDTrace/OpenTelemetry/Configuration.php

src/DDTrace/OpenTelemetry/CompositeResolver.php

src/DDTrace/OpenTelemetry/Detectors/Environment.php

src/DDTrace/OpenTelemetry/Detectors/Service.php

tests/OpenTelemetry/Integration/MetricsTest.php

PROFeNoM · 2025-12-09T11:21:47Z

ext/ddtrace.c

+        } else if (params_count == 3 && FUNCTION_NAME_MATCHES("track_telemetry_metrics")) {
+            zval *metric_name = ZVAL_VARARG_PARAM(params, 0);
+            zval *metric_value = ZVAL_VARARG_PARAM(params, 1);
+            zval *tags = ZVAL_VARARG_PARAM(params, 2);
+            if (Z_TYPE_P(metric_name) == IS_STRING && Z_TYPE_P(tags) == IS_STRING) {
+                ddtrace_metric_register_buffer(Z_STR_P(metric_name), DDOG_METRIC_TYPE_COUNT, DDOG_METRIC_NAMESPACE_TRACERS);
+                ddtrace_metric_add_point(Z_STR_P(metric_name), zval_get_double(metric_value), Z_STR_P(tags));
+                RETVAL_TRUE;
+            }


(Major)
I believe we should type-validate metric_value here, just as we did for metric_name and tags, because currently we are calling zval_get_double(metric_value) without verifying it's numeric.

This may or may not cause a crash if someone passes a non-numeric vakue.

Bob just told me that "zval_get_double() is infallible and always safe to use", so perhaps I made you do this change for nothing, oops 😬

PROFeNoM

LGTM! Just one or two little things and its good to go for me 👍

src/bridge/_files_opentelemetry.php

PROFeNoM · 2025-12-10T09:51:08Z

ext/ddtrace.c

+        } else if (params_count == 3 && FUNCTION_NAME_MATCHES("track_telemetry_metrics")) {
+            zval *metric_name = ZVAL_VARARG_PARAM(params, 0);
+            zval *metric_value = ZVAL_VARARG_PARAM(params, 1);
+            zval *tags = ZVAL_VARARG_PARAM(params, 2);
+            if (Z_TYPE_P(metric_name) == IS_STRING && Z_TYPE_P(tags) == IS_STRING) {
+                ddtrace_metric_register_buffer(Z_STR_P(metric_name), DDOG_METRIC_TYPE_COUNT, DDOG_METRIC_NAMESPACE_TRACERS);
+                ddtrace_metric_add_point(Z_STR_P(metric_name), zval_get_double(metric_value), Z_STR_P(tags));
+                RETVAL_TRUE;
+            }


Bob just told me that "zval_get_double() is infallible and always safe to use", so perhaps I made you do this change for nothing, oops 😬

rachelyangdog added 13 commits October 22, 2025 14:33

WIP: otel metrics

3beebfe

fixes

532aa56

fix according to spec

3722931

edits

6050826

update to composite resolver

dd60e65

adding metricexporter

b7afe69

update and add config

c485338

remove fallback

2e90afd

update

f1fe803

adding DD_HOSTNAME

06ac1e0

otel detectors

c042420

otel version compatibility

8fd2dca

WIP: add otel metrics telemetry

40b616c

rachelyangdog requested review from a team as code owners November 13, 2025 20:56

rachelyangdog marked this pull request as draft November 13, 2025 20:56

rachelyangdog requested a review from bwoebi November 13, 2025 20:56

add file to bridge

6d6a836

rachelyangdog added 3 commits November 13, 2025 17:17

adding aggressive read

db514d7

getting rid of the prev commit

6ac3cfa

adding host fix

65226f9

rachelyangdog changed the title ~~WIP: otel metrics telemetry~~ feat: support OpenTelemetry Metrics Nov 17, 2025

rachelyangdog added 2 commits November 17, 2025 10:38

Merge branch 'master' into rachel.yang/otel-metrics-part2-telemetry

fc807f3

update span.php since main

c268c97

rachelyangdog marked this pull request as ready for review November 17, 2025 16:46

rachelyangdog added 3 commits November 17, 2025 11:57

potential fix

fcc3fd4

Merge branch 'master' into rachel.yang/otel-metrics-part2-telemetry

92b45bb

adding tests

98eb418

chatgpt-codex-connector bot reviewed Dec 9, 2025

View reviewed changes

PROFeNoM reviewed Dec 9, 2025

View reviewed changes

fixes from review

60b03a6

PROFeNoM approved these changes Dec 10, 2025

View reviewed changes

rachelyangdog added 5 commits December 10, 2025 16:01

feedback

c653c3c

Merge branch 'master' into rachel.yang/otel-metrics-part2-telemetry

1e0492d

Merge branch 'master' into rachel.yang/otel-metrics-part2-telemetry

48f9ea6

fix metrics unit tests and dependencies

4bdc71f

fix failing otel tests

0670208

feat: support OpenTelemetry Metrics #3487

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Benchmarks [ tracer ]

scenario:ComposerTelemetryBench/benchTelemetryParsing-opcache

scenario:ContextPropagationBench/benchExtractHeaders128Bit-opcache

scenario:ContextPropagationBench/benchExtractTraceContext64Bit-opcache

scenario:ContextPropagationBench/benchInject128Bit-opcache

scenario:HookBench/benchWithoutHook-opcache

scenario:LogsInjectionBench/benchLogsNullBaseline-opcache

scenario:LogsInjectionBench/benchLogsNullInjection-opcache

scenario:MessagePackSerializationBench/benchMessagePackSerialization

scenario:MessagePackSerializationBench/benchMessagePackSerialization-opcache

scenario:SamplingRuleMatchingBench/benchRegexMatching1

scenario:SamplingRuleMatchingBench/benchRegexMatching2

scenario:SamplingRuleMatchingBench/benchRegexMatching3

scenario:SamplingRuleMatchingBench/benchRegexMatching4

scenario:SpanBench/benchOpenTelemetryAPI

scenario:SpanBench/benchOpenTelemetryAPI-opcache

scenario:TraceSerializationBench/benchSerializeTrace

scenario:WordPressBench/benchWordPressBaseline-opcache

scenario:WordPressBench/benchWordPressDdprof-opcache

scenario:WordPressBench/benchWordPressOverhead-opcache

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rachelyangdog commented Nov 13, 2025 •

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