You want to configure a Spring Boot app to use an environment variable REDIS_URL, but if it's missing, fallback to localhost. Which application.properties line achieves this?

hard📝 Application Q8 of 15

Spring Boot - Application Configuration

You want to configure a Spring Boot app to use an environment variable REDIS_URL, but if it's missing, fallback to localhost. Which application.properties line achieves this?

Aredis.url=${REDIS_URL} || localhost

Bredis.url=${REDIS_URL?localhost}

Credis.url=%REDIS_URL%:localhost

Dredis.url=${REDIS_URL:localhost}

Step-by-Step Solution

Solution:

Step 1: Recall Spring Boot syntax for default environment variable values
Use ${VAR_NAME:default} to provide fallback if env var is missing.
Step 2: Match correct syntax for REDIS_URL fallback
The correct line is redis.url=${REDIS_URL:localhost}.
Final Answer:
redis.url=${REDIS_URL:localhost} -> Option D
Quick Check:
Default fallback syntax = ${VAR:default} [OK]

Quick Trick: Use ${VAR:default} for fallback values in Spring Boot config [OK]

Common Mistakes:

Using shell or Windows syntax for defaults
Using invalid operators like || or ? in properties
Forgetting to wrap variable in ${}

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You want to configure a Spring Boot app to use an environment variable REDIS_URL, but if it's missing, fallback to localhost. Which application.properties line achieves this?

Step 1: Recall Spring Boot syntax for default environment variable values

Step 2: Match correct syntax for REDIS_URL fallback

Final Answer:

Quick Check:

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