Ankur Mhatre
86246dc860
configuration-properties/ @ConfigurationProperties vs @Value on Spring Boot 4.1.1. The relaxed-binding matrix is generated by binding each spelling rather than transcribed, and re-checked against real processes -- the in-process probe was wrong twice before it was right. Records the three findings that came out of it: @Value does get relaxed resolution inside Spring Boot (Boot attaches ConfigurationPropertySources), the configuration processor silently stops generating metadata on JDK 23+ when declared as a plain dependency, and @Valid is not what makes nested constraints run. profiles-and-config/ Precedence, profiles, spring.config.import and config trees. /precedence reports every source holding a property in rank order with file and line, which turns "my profile file had no effect" into a two-line answer. Also pins the counterintuitive one: an imported file outranks the file that imported it. spring-aop/ Designators, proxy types, and aspects that do not fire. One advice per supported designator so the reference table is generated from real matches; all fourteen unsupported designators fed to the parser. Two corrections to the reference documentation: unsupported designators throw UnsupportedPointcutPrimitiveException (extends RuntimeException, not IllegalArgumentException), and spring-boot-starter-aop was renamed to spring-boot-starter-aspectj in Boot 4. 19 contract tests across the three modules, 15 captured transcripts, all regenerated by scripts/run-all.sh. Verified on Spring Boot 4.1.1, Spring Framework 7.0.9, JDK 25.0.4.1. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01Gip4srpzMwjgoba6uEfbr5
58 lines
2.2 KiB
Markdown
58 lines
2.2 KiB
Markdown
[← IDE metadata](07-ide-metadata.md) · [Index](../README.md)
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# 8. Diagnosing a value
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Endpoint: [`BindingDiagnosticsEndpoint`](../src/main/java/com/ankurm/configprops/web/BindingDiagnosticsEndpoint.java).
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"The property is set but the application does not see it" is the most common configuration bug,
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and it is hard for one reason: a value carries no visible provenance. Spring Boot tracks it
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anyway — every property loaded from a file or a config tree carries an `Origin` naming the
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resource and the line.
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```
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$ curl -s 'localhost:8080/diag/origin?name=demo.mail.host'
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{
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"property": "demo.mail.host",
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"effectiveValue": "smtp.example.com",
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"candidatesInPrecedenceOrder": [
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{
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"source": "OriginTrackedMapPropertySource {name='Config resource ... [application.yaml]'}",
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"value": "smtp.example.com",
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"origin": "class path resource [application.yaml] - 15:11"
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}
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]
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}
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```
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Line 15, column 11. Not "somewhere in your configuration".
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## How it works
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```java
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for (ConfigurationPropertySource source : ConfigurationPropertySources.get(environment)) {
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ConfigurationProperty property =
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source.getConfigurationProperty(ConfigurationPropertyName.of(name));
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if (property != null) {
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// property.getValue(), property.getOrigin(), source.getUnderlyingSource()
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}
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}
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```
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Iterating `ConfigurationPropertySources.get(...)` gives you the sources in precedence order.
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The first hit is the winner; everything after it exists and lost. A property with several
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holders is exactly what "my change had no effect" looks like from the inside — and the
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[profiles project](../../profiles-and-config) is entirely about that case.
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## Delete it before shipping
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This endpoint prints whatever a mounted secret contains. If you want it permanently, put it
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behind the management port and authentication, or use Actuator's `/actuator/env`, which does
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the same job with sanitisation built in.
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## Without an endpoint
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- `--debug` prints the auto-configuration report, not property origins.
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- Setting `logging.level.org.springframework.boot.context.config=TRACE` logs which config data
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resources were loaded, in order — useful when the question is "was my file read at all".
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- In a test, inject `Environment` and inspect `getPropertySources()` directly.
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