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Three new article modules: configuration binding, profiles and config data, Spring AOP

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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
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Ankur Mhatre
2026-09-08 16:36:17 +00:00
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# Spring Boot profiles, config import and config trees
Companion project for [**Spring Boot Profiles Done Right**](https://ankurm.com/) on ankurm.com.
The question the project answers: you set a value in `application-prod.yaml`, deployed with
`prod` active, and the old value is still in effect. Why?
## Versions
| | |
|---|---|
| Spring Boot | 4.1.1 |
| Spring Framework | 7.0.9 |
| JDK | Eclipse Temurin 25.0.4.1 (LTS) |
## Quickstart
```bash
export JAVA_HOME=/path/to/jdk-25
mvn -DskipTests package
./scripts/run-all.sh # regenerate every transcript in docs/output/
mvn test # 6 contract tests
```
## Profiles
| Profile | What it demonstrates |
|---|---|
| `prod` | a profile group expanding to `prod`, `prod-db`, `prod-metrics` |
| `import` | `spring.config.import`, and the imported file winning |
| `multidoc` | one file, three documents, activated by condition |
| `badactivation` | `spring.profiles.active` set from a profile-specific document — refused |
| `staging` | the conditional document inside `application-multidoc.yaml` |
## Endpoints
| Endpoint | Purpose |
|---|---|
| `GET /precedence?name=` | every source holding a property, ranked, with file and line |
| `GET /sources` | the live property-source stack in precedence order |
Diagnostics. Delete before shipping, or use Actuator's `/actuator/env`, which sanitises.
## Documentation
1. [The precedence list](docs/01-the-precedence-list.md)
2. [Profiles: files, documents and groups](docs/02-profiles.md)
3. [Seeing precedence instead of reasoning about it](docs/03-seeing-precedence.md)
4. [Why your profile-specific file lost](docs/04-why-your-profile-file-lost.md)
5. [`spring.config.import`](docs/05-config-import.md)
6. [Config trees and Kubernetes ConfigMaps](docs/06-config-trees-and-configmaps.md)
## Captured output
| File | Produced by |
|---|---|
| [`00-versions.txt`](docs/output/00-versions.txt) | `scripts/demo-versions.sh` |
| [`01-precedence.txt`](docs/output/01-precedence.txt) | `scripts/demo-precedence.sh` |
| [`02-profile-file-loses.txt`](docs/output/02-profile-file-loses.txt) | `scripts/demo-profile-file-loses.sh` |
| [`03-config-tree.txt`](docs/output/03-config-tree.txt) | `scripts/demo-config-tree.sh` |
| [`04-import-and-multidoc.txt`](docs/output/04-import-and-multidoc.txt) | `scripts/demo-import-and-multidoc.sh` |
## The short answer
Config data — every file you write, profile-specific ones included — is item 3 in Spring Boot's
documented precedence list. OS environment variables are item 5. Later items win. A
profile-specific file beats other files and loses to the weakest environment variable on the
host.
## The one that surprises people
`spring.config.import` does not behave like `#include`. The **imported** file is processed after
the file that declared the import, so it **wins**. Import a shared baseline expecting to
override it and every key it sets will quietly beat yours.