Update Prometheus Exporter dependencies to use no-protobuf formats (and adds test) by zeitlinger · Pull Request #7664 · open-telemetry/opentelemetry-java

zeitlinger · 2025-09-17T07:46:00Z

aligns test and prod dependencies better - I guess this was the reason why the bug was introduced in c60fbe1
adds a test for protobuf
- the test would have passed even with the bug, because the proto dependency was in the test classpath
- we could add an end to end test that similar to https://github.com/open-telemetry/opentelemetry-java-examples/tree/main/logging-k8s-stdout-otlp-json to avoid having test dependencies

codecov · 2025-09-17T08:02:47Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.06%. Comparing base (1c5dd50) to head (1efe215).
⚠️ Report is 7 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##               main    #7664   +/-   ##
=========================================
  Coverage     90.06%   90.06%           
  Complexity     7104     7104           
=========================================
  Files           805      805           
  Lines         21484    21484           
  Branches       2093     2093           
=========================================
  Hits          19349    19349           
  Misses         1472     1472           
  Partials        663      663

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jack-berg · 2025-09-17T21:07:10Z

Here's the runtime classpath back in 1.50.0:

runtimeClasspath - Runtime classpath of source set 'main'.
+--- project :sdk:metrics
|    +--- project :api:all
|    |    \--- project :context
|    \--- project :sdk:common
|         \--- project :api:all (*)
+--- project :dependencyManagement
|    +--- com.fasterxml.jackson:jackson-bom:{strictly 2.19.0} -> 2.19.0
|    +--- com.google.guava:guava-bom:{strictly 33.4.8-jre} -> 33.4.8-jre
|    +--- com.google.protobuf:protobuf-bom:{strictly 4.30.2} -> 4.30.2
|    +--- com.squareup.okhttp3:okhttp-bom:{strictly 4.12.0} -> 4.12.0
|    +--- com.squareup.okio:okio-bom:{strictly 3.11.0} -> 3.11.0
|    +--- io.grpc:grpc-bom:{strictly 1.72.0} -> 1.72.0
|    +--- io.netty:netty-bom:{strictly 4.2.1.Final} -> 4.2.1.Final
|    +--- io.zipkin.brave:brave-bom:{strictly 6.2.0} -> 6.2.0
|    +--- io.zipkin.reporter2:zipkin-reporter-bom:{strictly 3.5.0} -> 3.5.0
|    +--- org.assertj:assertj-bom:{strictly 3.27.3} -> 3.27.3
|    +--- org.testcontainers:testcontainers-bom:{strictly 1.21.0} -> 1.21.0
|    +--- org.snakeyaml:snakeyaml-engine:{strictly 2.9} -> 2.9
|    +--- io.prometheus:prometheus-metrics-exporter-httpserver:1.3.6 (c)
|    \--- io.prometheus:prometheus-metrics-exposition-formats:1.3.6 (c)
+--- project :exporters:common
|    +--- project :api:all (*)
|    \--- project :sdk-extensions:autoconfigure-spi
|         \--- project :sdk:all
|              +--- project :api:all (*)
|              +--- project :sdk:common (*)
|              +--- project :sdk:trace
|              |    +--- project :api:all (*)
|              |    \--- project :sdk:common (*)
|              +--- project :sdk:metrics (*)
|              \--- project :sdk:logs
|                   +--- project :api:all (*)
|                   \--- project :sdk:common (*)
+--- project :sdk-extensions:autoconfigure-spi (*)
\--- io.prometheus:prometheus-metrics-exporter-httpserver -> 1.3.6
     \--- io.prometheus:prometheus-metrics-exporter-common:1.3.6
          +--- io.prometheus:prometheus-metrics-model:1.3.6
          +--- io.prometheus:prometheus-metrics-exposition-textformats:1.3.6
          |    +--- io.prometheus:prometheus-metrics-model:1.3.6
          |    \--- io.prometheus:prometheus-metrics-config:1.3.6
          \--- io.prometheus:prometheus-metrics-exposition-formats:1.3.6
               \--- io.prometheus:prometheus-metrics-exposition-textformats:1.3.6 (*)

And here's the classpath as of this PR:

runtimeClasspath - Runtime classpath of source set 'main'.
+--- project :sdk:metrics
|    +--- project :api:all
|    |    \--- project :context
|    |         \--- project :common
|    \--- project :sdk:common
|         \--- project :api:all (*)
+--- project :dependencyManagement
|    +--- com.fasterxml.jackson:jackson-bom:{strictly 2.20.0} -> 2.20.0
|    +--- com.google.guava:guava-bom:{strictly 33.4.8-jre} -> 33.4.8-jre
|    +--- com.google.protobuf:protobuf-bom:{strictly 4.32.1} -> 4.32.1
|    |    \--- com.google.protobuf:protobuf-java:4.32.1 (c)
|    +--- com.squareup.okhttp3:okhttp-bom:{strictly 5.1.0} -> 5.1.0
|    +--- com.squareup.okio:okio-bom:{strictly 3.16.0} -> 3.16.0
|    +--- io.grpc:grpc-bom:{strictly 1.75.0} -> 1.75.0
|    +--- io.netty:netty-bom:{strictly 4.2.6.Final} -> 4.2.6.Final
|    +--- io.zipkin.brave:brave-bom:{strictly 6.3.0} -> 6.3.0
|    +--- io.zipkin.reporter2:zipkin-reporter-bom:{strictly 3.5.1} -> 3.5.1
|    +--- org.assertj:assertj-bom:{strictly 3.27.4} -> 3.27.4
|    +--- org.testcontainers:testcontainers-bom:{strictly 1.21.3} -> 1.21.3
|    +--- org.snakeyaml:snakeyaml-engine:{strictly 2.10} -> 2.10
|    +--- io.prometheus:prometheus-metrics-exporter-httpserver:1.3.10 (c)
|    \--- io.prometheus:prometheus-metrics-exposition-formats-no-protobuf:1.3.10 (c)
+--- project :exporters:common
|    +--- project :api:all (*)
|    \--- project :sdk-extensions:autoconfigure-spi
|         \--- project :sdk:all
|              +--- project :api:all (*)
|              +--- project :sdk:common (*)
|              +--- project :sdk:trace
|              |    +--- project :api:all (*)
|              |    \--- project :sdk:common (*)
|              +--- project :sdk:metrics (*)
|              \--- project :sdk:logs
|                   +--- project :api:all (*)
|                   \--- project :sdk:common (*)
+--- project :sdk-extensions:autoconfigure-spi (*)
+--- io.prometheus:prometheus-metrics-exporter-httpserver -> 1.3.10
|    \--- io.prometheus:prometheus-metrics-exporter-common:1.3.10
|         +--- io.prometheus:prometheus-metrics-model:1.3.10
|         \--- io.prometheus:prometheus-metrics-exposition-textformats:1.3.10
|              +--- io.prometheus:prometheus-metrics-model:1.3.10
|              \--- io.prometheus:prometheus-metrics-config:1.3.10
\--- io.prometheus:prometheus-metrics-exposition-formats-no-protobuf -> 1.3.10
     +--- io.prometheus:prometheus-metrics-exposition-textformats:1.3.10 (*)
     \--- com.google.protobuf:protobuf-java:4.31.1 -> 4.32.1

Notably, the com.google.protobuf:protobuf-java transitive dependency is new, which I what I believe I was trying to avoid in this comment and associated commit.

What's going on here? How was protobuf export supported previously without the com.google.protobuf:protobuf-java dependency? Was it possibly coming as a transitive dependency from elsewhere?

zeitlinger · 2025-09-18T06:40:41Z

How was protobuf export supported previously without the com.google.protobuf:protobuf-java dependency?

protobuf was shaded previously
now you have a choice of using the bundled protobuf or without shading (prometheus-metrics-exposition-formats-no-protobuf)

jack-berg · 2025-09-18T13:58:04Z

Got it thanks for the context.

Ok, so we have a decision to make. Do we (opentelemetry-java) want to make protobuf serialization opt-in or opt-out? When protobuf was shaded, we had no choice. I lean towards opt-out (which is what this PR does), since an opt-in strategy makes it cumbersome to use protobuf + prometheus + otel java agent.

jack-berg · 2025-09-18T13:58:44Z

sdk-extensions/autoconfigure/build.gradle.kts

        implementation(project(":exporters:prometheus"))
-        implementation("io.prometheus:prometheus-metrics-exporter-httpserver")
+        implementation("io.prometheus:prometheus-metrics-exporter-httpserver") {
+          exclude(group = "io.prometheus", module = "prometheus-metrics-exposition-formats")


What is the goal of this exclusion?

it aligns the classpath with what is used for compile - see

opentelemetry-java/exporters/prometheus/build.gradle.kts

Line 15 in 1efe215

implementation("io.prometheus:prometheus-metrics-exporter-httpserver") {

jack-berg · 2025-09-18T14:01:44Z

.../prometheus/src/test/java/io/opentelemetry/exporter/prometheus/PrometheusHttpServerTest.java

+                    HttpMethod.GET,
+                    "/metrics",
+                    HttpHeaderNames.ACCEPT,
+                    "Accept: application/vnd.google.protobuf;proto=io.prometheus.client.MetricFamily"))


Technically we have coverage for this here already: https://github.com/open-telemetry/opentelemetry-java/blob/main/exporters/prometheus/src/test/java/io/opentelemetry/exporter/prometheus/PrometheusHttpServerTest.java#L587-L595

I didn't see - this just didn't fail, because the dependency in question has been added the test classpath..

zeitlinger · 2025-09-18T16:32:21Z

I lean towards opt-out

I agree - make it easy to use by default

zeitlinger · 2025-09-18T16:52:53Z

@jack-berg @jkwatson as agreed (in SIG), we'll create a patch release once this is merged

…nd adds test) (#7664)

…nd adds test) (open-telemetry#7664)

zeitlinger added 2 commits September 17, 2025 09:23

add protobuf test

d211d01

fix protobuf

aa65007

zeitlinger requested a review from a team as a code owner September 17, 2025 07:46

zeitlinger self-assigned this Sep 17, 2025

zeitlinger mentioned this pull request Sep 17, 2025

v1.51 breaks prometheus protobuf format (native histogram support) #7659

Closed

zeitlinger changed the title ~~Update Prometheus Exporter dependencies to use no-protobuf formats~~ Update Prometheus Exporter dependencies to use no-protobuf formats (and adds test) Sep 17, 2025

fix protobuf

1efe215

jack-berg reviewed Sep 18, 2025

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jack-berg approved these changes Sep 18, 2025

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jkwatson merged commit 04015cd into open-telemetry:main Sep 18, 2025
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github-actions bot pushed a commit that referenced this pull request Sep 18, 2025

Update Prometheus Exporter dependencies to use no-protobuf formats (a…

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…nd adds test) (#7664)

otelbot bot mentioned this pull request Sep 18, 2025

[release/v1.54.x] Update Prometheus Exporter dependencies to use no-protobuf formats (and adds test) #7670

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zeitlinger deleted the prom-protobuf-fix branch September 19, 2025 12:42

the-clam pushed a commit to the-clam/opentelemetry-java that referenced this pull request Nov 6, 2025

Update Prometheus Exporter dependencies to use no-protobuf formats (a…

6a143f7

…nd adds test) (open-telemetry#7664)

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Update Prometheus Exporter dependencies to use no-protobuf formats (and adds test)#7664

Update Prometheus Exporter dependencies to use no-protobuf formats (and adds test)#7664
jkwatson merged 3 commits intoopen-telemetry:mainfrom
zeitlinger:prom-protobuf-fix

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