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
60 lines
2.5 KiB
Markdown
60 lines
2.5 KiB
Markdown
[← Profiles](02-profiles.md) · [Index](../README.md) · [Why your profile file lost →](04-why-your-profile-file-lost.md)
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# 3. Seeing precedence instead of reasoning about it
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Endpoint: [`PrecedenceEndpoint`](../src/main/java/com/ankurm/profiles/web/PrecedenceEndpoint.java).
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Transcript: [`01-precedence.txt`](output/01-precedence.txt).
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Set `demo.greeting` from five places at once and ask which won:
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```
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$ DEMO_GREETING=from-environment-variable \
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java -Ddemo.greeting=from-system-property \
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-jar profiles-and-config-1.0.0.jar --spring.profiles.active=prod \
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--demo.greeting=from-command-line-argument
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```
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```
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"effectiveValue": "from-command-line-argument",
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"activeProfiles": ["prod", "prod-db", "prod-metrics"],
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"holders": [
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{ "rank": 1, "value": "from-command-line-argument", "source": "commandLineArgs" },
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{ "rank": 2, "value": "from-system-property", "source": "systemProperties" },
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{ "rank": 3, "value": "from-environment-variable", "source": "systemEnvironment" },
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{ "rank": 4, "value": "from-application-prod-yaml", "origin": "application-prod.yaml - 4:13" },
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{ "rank": 5, "value": "from-application-yaml", "origin": "application.yaml - 21:13" }
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],
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"shadowedCount": 4
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```
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Five sources hold the property. Four of them lose. Each one that came from a file names its
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line.
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## The whole implementation
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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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// rank = position, property.getValue(), property.getOrigin()
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}
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}
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```
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`ConfigurationPropertySources.get(...)` returns the sources in precedence order. Iterate,
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collect every hit, and the first is the winner. That is the entire diagnostic.
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## Why this beats reading the list
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The documented order is correct but abstract. It does not tell you that a `DEMO_GREETING` left
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over from a shell three weeks ago is sitting at rank 3, and that is the actual question.
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## Alternatives if you would rather not add an endpoint
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- Actuator's `/actuator/env` gives the same information with sanitisation, and
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`/actuator/env/{name}` narrows to one property. Prefer it in anything real.
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- `logging.level.org.springframework.boot.context.config=TRACE` logs which config data
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resources were loaded and in what order.
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- `--debug` does *not* show this. It prints the auto-configuration report.
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