Environment-based profiles in Spring Boot - Step-by-Step Execution

Concept Flow - Environment-based profiles

Start Application

↓

Check Active Profile

↓

Load Profile-Specific Config

↓

Initialize Beans with Profile

↓

Run Application with Config

↓

End

The application starts, checks which profile is active, loads the matching configuration, initializes beans accordingly, and runs with that setup.

Execution Sample

Spring Boot

spring.profiles.active=dev

@Configuration
@Profile("dev")
public class DevConfig {
  // dev beans
}

This code activates the 'dev' profile and loads beans only when 'dev' is active.

Execution Table

Step	Action	Profile Active	Config Loaded	Beans Initialized	Result
1	Start Application	none yet	none	none	Application starting
2	Read spring.profiles.active	dev	application-dev.properties	none	Dev profile active
3	Initialize Beans	dev	application-dev.properties	DevConfig beans	Beans ready for dev
4	Run Application	dev	application-dev.properties	DevConfig beans	App running with dev config
5	End	dev	application-dev.properties	DevConfig beans	Application running

💡 Application runs with the 'dev' profile active, loading dev-specific config and beans.

Variable Tracker

Variable	Start	After Step 2	After Step 3	Final
activeProfile	null	dev	dev	dev
configLoaded	none	application-dev.properties	application-dev.properties	application-dev.properties
beansInitialized	none	none	DevConfig beans	DevConfig beans

Key Moments - 2 Insights

Why does the application load dev beans only when the 'dev' profile is active?

Because @Profile("dev") annotation tells Spring to initialize those beans only if the active profile matches 'dev', as shown in execution_table step 3.

What happens if no profile is set in spring.profiles.active?

Spring loads default config and beans without any profile-specific ones, so profile-specific beans are not initialized. This is implied by the 'none yet' profile in step 1.

Visual Quiz - 3 Questions

Look at the execution table, what is the active profile at step 2?

A dev

B prod

C none

D test

💡 Hint

Check the 'Profile Active' column at step 2 in the execution_table.

At which step are the dev beans initialized?

A Step 1

B Step 3

C Step 2

D Step 4

💡 Hint

Look at the 'Beans Initialized' column in the execution_table.

If spring.profiles.active was set to 'prod', how would the configLoaded variable change?

A It would be null

B It would remain application-dev.properties

C It would be application-prod.properties

D It would be application-default.properties

💡 Hint

Refer to variable_tracker and how configLoaded matches the active profile.

Concept Snapshot

Environment-based profiles in Spring Boot:
- Use spring.profiles.active to set the active profile.
- Annotate beans/config with @Profile("name") to load conditionally.
- Spring loads profile-specific properties like application-dev.properties.
- Only beans for the active profile initialize.
- Helps separate configs for dev, test, prod environments.

Full Transcript

When a Spring Boot application starts, it checks which profile is active by reading the spring.profiles.active property. Based on this, it loads the matching profile-specific configuration file, such as application-dev.properties for the 'dev' profile. Then, Spring initializes only the beans annotated with @Profile matching the active profile. This way, the application runs with environment-specific settings and beans. If no profile is set, default configurations and beans load. This mechanism helps developers easily switch between environments like development, testing, and production by changing one setting.