@Profile for environment-specific beans in Spring Boot - Step-by-Step Execution

Concept Flow - @Profile for environment-specific beans

Start Application

↓

Check Active Profiles

↓

Match Bean @Profile?

No→Skip Bean

Yes↓

Register Bean in Context

↓

Use Bean in Application

↓

Application Runs with Correct Beans

The application starts, checks which profiles are active, registers only beans matching those profiles, and uses them during runtime.

Execution Sample

Spring Boot

@Configuration
@Profile("dev")
public class DevConfig {
  @Bean
  public DataSource devDataSource() {
    return new DevDataSource();
  }
}

Defines a bean that is only created when the 'dev' profile is active.

Execution Table

Step	Active Profiles	Bean Class	@Profile Annotation	Bean Registered?	Reason
1	dev	DevConfig	dev	Yes	Active profile matches @Profile
2	dev	ProdConfig	prod	No	Active profile 'dev' does not match 'prod'
3	prod	DevConfig	dev	No	Active profile 'prod' does not match 'dev'
4	prod	ProdConfig	prod	Yes	Active profile matches @Profile
5	none	DevConfig	dev	No	No active profiles, bean skipped
6	none	ProdConfig	prod	No	No active profiles, bean skipped

💡 Beans are only registered if their @Profile matches an active profile; otherwise, they are skipped.

Variable Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	After Step 4	Final
activeProfiles	[]	["dev"]	["dev"]	["prod"]	["prod"]	[]
DevConfig Bean Registered	false	true	true	false	false	false
ProdConfig Bean Registered	false	false	false	false	true	false

Key Moments - 2 Insights

Why is a bean with @Profile("dev") not created when the active profile is 'prod'?

Because the @Profile annotation tells Spring to only register the bean if the active profile matches exactly. See execution_table rows 3 and 4 where the mismatch causes skipping.

What happens if no profiles are active but beans have @Profile annotations?

Beans with @Profile annotations are not registered if no profiles are active, as shown in execution_table rows 5 and 6.

Visual Quiz - 3 Questions

Look at the execution_table, at step 2, is the ProdConfig bean registered when 'dev' profile is active?

A Yes, it is registered

B Only partially registered

C No, it is not registered

D It causes an error

💡 Hint

Check the 'Bean Registered?' column at step 2 in the execution_table.

According to variable_tracker, what is the value of 'activeProfiles' after step 4?

A ["dev"]

B ["prod"]

C []

D ["dev", "prod"]

💡 Hint

Look at the 'activeProfiles' row and the 'After Step 4' column in variable_tracker.

If the active profile is empty, what happens to beans annotated with @Profile("dev")?

A They are skipped

B They are registered anyway

C They cause a startup error

D They are registered but inactive

💡 Hint

Refer to execution_table rows 5 and 6 where no profiles are active.

Concept Snapshot

@Profile annotation limits bean creation to specific environments.
Activate profiles via application.properties or command line.
Only beans matching active profiles load into context.
No active profile means @Profile beans are skipped.
Use for dev, test, prod environment configs.

Full Transcript

When a Spring Boot application starts, it checks which profiles are active. Beans annotated with @Profile are only created if their profile matches one of the active profiles. For example, a bean with @Profile("dev") is created only if the 'dev' profile is active. If the active profile is 'prod', that bean is skipped. If no profiles are active, all @Profile beans are skipped. This helps run different beans in different environments like development or production. The execution table shows steps where beans are registered or skipped based on active profiles. The variable tracker shows how activeProfiles and bean registration flags change during startup.