Profile-based configuration in Spring Boot - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to specify the active Spring profile in application.properties.

Spring Boot

spring.profiles.active=[1]

Drag options to blanks, or click blank then click option'

Adefault

Bactive

Cprofile

Ddev

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'active' or 'profile' as the profile name instead of a real profile like 'dev'.

Leaving the value empty.

The property spring.profiles.active sets the active profile. Here, dev is a common profile name.

2fill in blank

medium

Complete the filename to create a profile-specific properties file for the test profile.

Spring Boot

application-[1].properties

Drag options to blanks, or click blank then click option'

Aactive

Bdefault

Ctest

Dprofile

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'default' or 'active' instead of the actual profile name.

Misspelling the profile name.

Spring Boot loads application-{profile}.properties files based on the active profile. For the test profile, the file is application-test.properties.

3fill in blank

hard

Fix the error in the annotation to activate the prod profile in a Spring Boot test class.

Spring Boot

@ActiveProfiles("[1]")

Drag options to blanks, or click blank then click option'

Aprod

Bdefault

Cproduction

Dprofile

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'production' instead of 'prod'.

Using 'default' which is not a profile name.

The @ActiveProfiles annotation activates the specified profile for tests. The profile name must exactly match the profile defined in your configuration, here prod.

4fill in blank

hard

Fill both blanks to define a bean that is only created when the dev profile is active.

Spring Boot

@Bean
@Profile([1])
public DataSource dataSource() {
    return [2];
}

Drag options to blanks, or click blank then click option'

Adev

Bprod

C"dev"

Dnew HikariDataSource()

Attempts:

3 left

💡 Hint

Common Mistakes

Not quoting the profile name in @Profile.

Returning a class name instead of an instance.

The @Profile annotation requires the profile name as a string, so it must be quoted. The bean method returns a new instance of the data source implementation.

5fill in blank

hard

Fill all three blanks to create a YAML profile-specific configuration for staging with a custom server port.

Spring Boot

spring:
  profiles:
    active: [1]
  server:
    port: [2]

logging:
  level:
    root: [3]

Drag options to blanks, or click blank then click option'

Astaging

B8085

CDEBUG

Dprod

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'prod' instead of 'staging' for the profile.

Setting port as a string instead of a number.

Using lowercase logging levels.

This YAML snippet activates the staging profile, sets the server port to 8085, and sets the root logging level to DEBUG.

Practice

1. What is the main purpose of using profiles in Spring Boot configuration?

easy

A. To switch application settings easily for different environments

B. To write Java code faster

C. To create user interfaces

D. To manage database connections manually

Solution

1. Step 1: Understand what profiles do

   Profiles allow you to have different settings for different environments like development, testing, and production.

2. Step 2: Identify the main use

   Switching settings easily means you can run the same app with different configurations without changing code.

3. Final Answer:

   To switch application settings easily for different environments -> Option A

4. Quick Check:

   Profiles = environment-specific settings [OK]

Hint: Profiles = different settings for different environments [OK]

Common Mistakes:

• Thinking profiles are for writing code
• Confusing profiles with UI design
• Believing profiles manage database manually

2. Which of the following is the correct way to name a Spring Boot properties file for a profile named dev?

easy

A. application-dev.properties

B. application.properties-dev

C. dev-application.properties

D. application_dev.properties

Solution

1. Step 1: Recall Spring Boot profile file naming

   Spring Boot expects profile-specific files named as application-{profile}.properties.

2. Step 2: Match the correct pattern

   For profile 'dev', the file should be application-dev.properties.

3. Final Answer:

   application-dev.properties -> Option A

4. Quick Check:

   Profile file = application-{profile}.properties [OK]

Hint: Profile files use dash between application and profile [OK]

Common Mistakes:

• Using underscore instead of dash
• Placing profile after .properties
• Starting filename with profile name

3. Given these files:
application.properties contains server.port=8080
application-prod.properties contains server.port=9090
And the active profile is set to prod, what port will the Spring Boot app run on?

medium

A. 8080

B. 9090

C. Both 8080 and 9090

D. No port will be set

Solution

1. Step 1: Understand profile override behavior

   Properties in profile-specific files override those in the default application.properties when the profile is active.

2. Step 2: Apply active profile 'prod'

   Since 'prod' is active, server.port=9090 from application-prod.properties overrides 8080.

3. Final Answer:

   9090 -> Option B

4. Quick Check:

   Active profile properties override default [OK]

Hint: Active profile settings override defaults [OK]

Common Mistakes:

• Assuming default always applies
• Thinking both ports run simultaneously
• Ignoring profile activation

4. You wrote spring.profiles.active=dev in application.properties, but your app still uses default settings. What is the likely problem?

medium

A. The dev profile is not supported by Spring Boot

B. You need to restart the app after changing profiles

C. The profile-specific file is named application_dev.properties instead of application-dev.properties

D. Profiles cannot be set in application.properties

Solution

1. Step 1: Check profile file naming

   Spring Boot requires profile files named with dash, not underscore.

2. Step 2: Identify mismatch

   If the file is named application_dev.properties, Spring Boot won't recognize it for profile 'dev'.

3. Final Answer:

   Incorrect profile file naming with underscore -> Option C

4. Quick Check:

   Profile file must use dash, not underscore [OK]

Hint: Use dash, not underscore, in profile filenames [OK]

Common Mistakes:

• Thinking profiles can't be set in application.properties
• Forgetting to restart app (usually needed but not main issue here)
• Believing 'dev' profile is unsupported

5. You want to activate the test profile without changing application.properties. Which of these is a valid way to do it when running your Spring Boot app from the command line?

hard

A. java -jar app.jar -profile test

B. java -jar app.jar -Dspring.profiles.active=test

C. java -jar app.jar --profile=test

D. java -jar app.jar --spring.profiles.active=test

Solution

1. Step 1: Recall command line profile activation syntax

   Spring Boot uses --spring.profiles.active=profile to activate profiles via command line arguments.

2. Step 2: Check each option

   java -jar app.jar --spring.profiles.active=test uses the correct Spring Boot command-line syntax. java -jar app.jar -Dspring.profiles.active=test incorrectly places the -D JVM argument after -jar; correct would be java -Dspring.profiles.active=test -jar app.jar. Flags like -profile test and --profile=test are not supported by Spring Boot.

3. Final Answer:

   java -jar app.jar --spring.profiles.active=test -> Option D

4. Quick Check:

   Use --spring.profiles.active=profile on command line [OK]

Hint: Use --spring.profiles.active=profile to activate profiles [OK]

Common Mistakes:

• Using -profile or --profile flags incorrectly
• Confusing JVM -D options without proper placement
• Trying to set profile inside application.properties only