Make declarative config parsing and mapping pluggable by ash-thakur-rh · Pull Request #8983 · open-telemetry/opentelemetry-java

ash-thakur-rh · 2026-10-28T13:51:16Z

Description:

Added a dedicated declarative-config-spi module for the mapper and YAML parser interfaces.
Added the Jackson 2 mapper as a runtime dependency so it is available by default.
Documented how to exclude the Jackson 2 mapper and register a custom mapper, such as one using Jackson 3.
Updated OSGi metadata and integration coverage for declarative configuration.
Updated the declarative configuration README and changelog.
Verified the affected declarative config, autoconfigure, API incubator, Graal, and OSGi test suites. Will fix other if there are other test failures.
Did a manual end-to-end check in a local consumer project, excluded the Jackson 2 adapter, registered a Jackson 3 mapper through ServiceLoader, and verified configuration parsing and mapping.

Add parser and mapper SPIs, and move the Jackson 2 mapper into an optional adapter module. Signed-off-by: Ashish Thakur <ashishth@redhat.com>

Signed-off-by: Ashish Thakur <ashishth@redhat.com>

linux-foundation-easycla · 2026-10-28T13:51:25Z

The committers listed above are authorized under a signed CLA.

✅ login: ash-thakur-rh / name: Ashish Thakur (1b41300, 93ffc5d, a103e4d)

opentelemetry-pr-dashboard · 2026-10-28T13:52:55Z

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codecov · 2026-10-28T14:08:36Z

Codecov Report

❌ Patch coverage is 92.91339% with 9 lines in your changes missing coverage. Please review.
✅ Project coverage is 90.36%. Comparing base (53d860b) to head (82dfaa7).

Files with missing lines	Patch %	Lines
...nfig/internal/DeclarativeConfigProviderLoader.java	82.60%	2 Missing and 2 partials ⚠️
...g/internal/DeclarativeConfigurationMapperUtil.java	55.55%	4 Missing ⚠️
...veconfig/model/internal/ExtensionPropertyUtil.java	75.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #8983      +/-   ##
============================================
+ Coverage     90.33%   90.36%   +0.02%     
- Complexity    11017    11034      +17     
============================================
  Files          1021     1025       +4     
  Lines         30124    30168      +44     
  Branches       3933     3939       +6     
============================================
+ Hits          27214    27261      +47     
+ Misses         1953     1947       -6     
- Partials        957      960       +3

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Signed-off-by: Ashish Thakur <ashishth@redhat.com>

ash-thakur-rh · 2026-10-28T14:37:41Z

The committers listed above are authorized under a signed CLA.

✅ login: ash-thakur-rh / name: Ashish Thakur (1b41300, 93ffc5d, a103e4d, bf33c6f)

jack-berg

This is pretty close to the shape I imagined. Couple of things to think through tho.

jack-berg · 2026-11-03T23:04:42Z

+ * This class is internal and is hence not for public use. Its APIs are unstable and can change at
+ * any time.
+ */
+public final class SnakeYamlDeclarativeConfigurationParser


Interesting.. so we have a dedicated jackson module, but build the snakeyaml implementation into declarative-config directly despite it being pluggable via SPI.

I think we need to think this through and be consistent.

yes, I agree. we can move the snakeyaml impl to its own. For now, I will have sankeyaml impl in declarative-config until we think this through.

Ok upon further thought, I think we need to either rip out the DeclarativeConfigurationYamlParser SPI or split the snakeyaml out into its own module now.

The argument to rip out the yaml SPI is that nobody has reported issues with snakeyaml yet so its possible its stable enough / ubiquitous enough that nobody wants it pluggable. The argument to keep it and split snakeymal into its own module is that there are other YAML parsers out there and it may be inevitable that someone eventually takes issue with snakeyaml and wants to bring their own.

I still lean towards keeping the yaml SPI since it buys a mitigation step in case snakeyaml library falls into disrepair or has some other issue that makes it a toxic dependency. So let's break out a snakeyaml module.

ash-thakur-rh · 2026-11-05T04:59:24Z

This is pretty close to the shape I imagined. Couple of things to think through tho.

Thanks @jack-berg , will take care of the things suggested.

Signed-off-by: Ashish Thakur <ashishth@redhat.com>

ash-thakur-rh · 2026-11-11T11:23:52Z

/dashboard route:reviewers

opentelemetry-pr-dashboard · 2026-11-11T11:24:06Z

@ash-thakur-rh, this pull request was routed to reviewers. The handoff remains active across pushes until newer actionable human feedback arrives. Top-level feedback through this request will not return; unresolved review threads remain open.

jack-berg · 2026-11-11T12:39:17Z

+   * @param <T> the target type
+   * @return the converted value
+   */
+  <T> T convert(Object value, Class<T> targetType);


The new SPI methods convert / toMap / DeclarativeConfigurationYamlParser.parse throw under certain conditions. We should standardize the throws contract so callers can catch in a consistent way regardless of implementation.

jack-berg · 2026-11-11T12:48:18Z

+      Logger.getLogger(DeclarativeConfigProviderLoader.class.getName());
+
+  private static final ComponentLoader COMPONENT_LOADER =
+      ComponentLoader.forClassLoader(DeclarativeConfigProperties.class.getClassLoader());


We need to find a way for ComponentLoader to be a part of the contract and passed through from the caller. Every time we've loaded SPIs previously using a convenient class loader available to us, we eventually get an issue opened where someone needs that class loader to be configurable. That's why you see setComponentLoader style methods everywhere.

This is going to be disruptive for ExtensionPropertyUtil, which calls DeclarativeConfigurationMapper, and maybe the contracts in DeclarativeConfiguration itself since the parse operation currently doesn't have any overload which includes a ComponentLoader. If it proves too disruptive, let's skip and open an issue to followup.

jack-berg · 2026-11-11T12:52:26Z

+            MessageFormat.format(
+                "Multiple {0} providers found. Please include only one, or specify preference "
+                    + "setting {1} to the FQCN of the preferred provider.",
+                spiClass.getSimpleName(), configProperty));


We don't use this MessageFormat style anywhere in this repo so let's not start

Suggested change

MessageFormat.format(

"Multiple {0} providers found. Please include only one, or specify preference "

+ "setting {1} to the FQCN of the preferred provider.",

spiClass.getSimpleName(), configProperty));

"Multiple {0} providers found. Please include only one, or specify preference "

+ "setting {1} to the FQCN of the preferred provider.",

new Object[]{spiClass.getSimpleName(), configProperty});

jack-berg · 2026-11-11T13:07:00Z

+ * This class is internal and is hence not for public use. Its APIs are unstable and can change at
+ * any time.
+ */
+public final class SnakeYamlDeclarativeConfigurationParser


Ok upon further thought, I think we need to either rip out the DeclarativeConfigurationYamlParser SPI or split the snakeyaml out into its own module now.

The argument to rip out the yaml SPI is that nobody has reported issues with snakeyaml yet so its possible its stable enough / ubiquitous enough that nobody wants it pluggable. The argument to keep it and split snakeymal into its own module is that there are other YAML parsers out there and it may be inevitable that someone eventually takes issue with snakeyaml and wants to bring their own.

I still lean towards keeping the yaml SPI since it buys a mitigation step in case snakeyaml library falls into disrepair or has some other issue that makes it a toxic dependency. So let's break out a snakeyaml module.

jack-berg · 2026-11-11T13:11:51Z

  api(project(":sdk:all"))
  api(project(":api:incubator"))
-  compileOnly(project(":sdk-extensions:autoconfigure-spi"))
+  api(project(":sdk-extensions:autoconfigure-spi"))


This should be an implementation dependency on spi unless any spi classes are part of declarative config public facing API contracts

jack-berg · 2026-11-11T13:12:47Z

+* The built-in SnakeYAML parser and Jackson 2 mapper work by default. The mapper is supplied by
+  the `declarative-config-jackson2` module (`opentelemetry-sdk-extension-declarative-config-jackson2`
+  artifact). If you exclude that module, register a mapper provider of your own; otherwise,
+  operations that need mapping fail with a `DeclarativeConfigException`.


Tighten this up - too wordy.

ash-thakur-rh added 2 commits October 28, 2026 17:26

feat: Make declarative config parsing and mapping pluggable

1b41300

Add parser and mapper SPIs, and move the Jackson 2 mapper into an optional adapter module. Signed-off-by: Ashish Thakur <ashishth@redhat.com>

feat: dependency fix based on tests run

a103e4d

Signed-off-by: Ashish Thakur <ashishth@redhat.com>

opentelemetry-pr-dashboard Bot mentioned this pull request Oct 28, 2026

Pull Request Dashboard #8439

Open

feat: few changes for better arch

93ffc5d

Signed-off-by: Ashish Thakur <ashishth@redhat.com>

ash-thakur-rh marked this pull request as ready for review October 29, 2026 05:26

ash-thakur-rh requested a review from a team as a code owner October 29, 2026 05:26

jack-berg reviewed Nov 3, 2026

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ash-thakur-rh added 2 commits November 5, 2026 14:29

feat: fixes as per suggestions

bf33c6f

Signed-off-by: Ashish Thakur <ashishth@redhat.com>

feat: update to move mapper from internal package

8fcb020

Signed-off-by: Ashish Thakur <ashishth@redhat.com>

otelbot Bot added the api-change Changes to public API surface area label Nov 5, 2026

ash-thakur-rh added 2 commits November 5, 2026 15:54

feat: update to move mapper from internal package

fd8e4ac

Signed-off-by: Ashish Thakur <ashishth@redhat.com>

feat: minor fixes

657ee4a

Signed-off-by: Ashish Thakur <ashishth@redhat.com>

otelbot Bot removed the api-change Changes to public API surface area label Nov 5, 2026

feat: apply same logic to parser autoconfigure

cc4a52b

Signed-off-by: Ashish Thakur <ashishth@redhat.com>

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Merge branch 'main' into features/fe-config-spi

82dfaa7

jack-berg reviewed Nov 11, 2026

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