[Index](../README.md) · [Profiles →](02-profiles.md)

# 1. The precedence list

Spring Boot's documented order, lowest precedence first. Later entries win.

| # | Source |
|---|---|
| 1 | Default properties (`SpringApplication.setDefaultProperties`) |
| 2 | `@PropertySource` on `@Configuration` classes |
| 3 | **Config data** — `application.properties`, `application.yaml`, profile-specific files, `spring.config.import` |
| 4 | `RandomValuePropertySource` (`random.*`) |
| 5 | **OS environment variables** |
| 6 | Java system properties (`-D`) |
| 7 | JNDI attributes from `java:comp/env` |
| 8 | `ServletContext` init parameters |
| 9 | `ServletConfig` init parameters |
| 10 | `SPRING_APPLICATION_JSON` |
| 11 | Command-line arguments |
| 12 | `properties` on `@SpringBootTest` |
| 13 | `@DynamicPropertySource` |
| 14 | `@TestPropertySource` |
| 15 | Devtools global settings |

## The two rows that matter

**Item 3 covers every file you write.** `application.yaml`, `application-prod.yaml`, an
imported config tree, a mounted ConfigMap — all of it is config data, all of it at rank 3.

**Item 5 is above it.** Every environment variable outranks every file.

Profile-specific files beat non-profile files, and later imports beat earlier ones, but those
are orderings *within* item 3. Nothing inside item 3 can reach item 5.

That single fact explains the bug this project exists for, and
[chapter 4](04-why-your-profile-file-lost.md) walks through it with a transcript.

## Seeing it for real

`/sources` prints the live stack, which is more useful than the table because it shows exactly
which files were loaded:

```
   3. SimpleCommandLinePropertySource    commandLineArgs
   6. PropertiesPropertySource           systemProperties
   7. OriginAwareSystemEnvironmentPropertySource systemEnvironment
   9. OriginTrackedMapPropertySource     application-prod-metrics.yaml
  10. OriginTrackedMapPropertySource     application-prod-db.yaml
  11. OriginTrackedMapPropertySource     application-prod.yaml
  12. OriginTrackedMapPropertySource     application.yaml
```

Note rank 2 in the real stack, which the table does not mention:
`ConfigurationPropertySourcesPropertySource`, named `configurationProperties`. That is the
source Spring Boot attaches to give `${...}` placeholders the binder's relaxed name matching —
see the [binding project's chapter 2](../../configuration-properties/docs/02-relaxed-binding.md).