application.yml alternative in Spring Boot - Step-by-Step Execution

Concept Flow - application.yml alternative

Start Spring Boot App

↓

Check for application.yml

No↓

Check for application.properties

Yes↓

Load properties from application.properties

↓

Use loaded properties in app

↓

Run

Spring Boot first looks for application.yml. If not found, it checks for application.properties and loads it to configure the app.

Execution Sample

Spring Boot

server.port=8081
spring.datasource.url=jdbc:mysql://localhost:3306/db
logging.level.root=INFO

This application.properties file sets server port, database URL, and logging level as an alternative to application.yml.

Execution Table

Step	File Checked	Found?	Action	Result
1	application.yml	No	Skip to next config file	No YAML config loaded
2	application.properties	Yes	Load properties	Properties loaded into environment
3	Use properties	N/A	Configure app with loaded properties	Server port=8081, DB URL set, Logging=INFO
4	Start app	N/A	Run with configured settings	App runs on port 8081 with given configs

💡 application.yml not found, application.properties found and loaded, app configured and started

Variable Tracker

Variable	Start	After Step 2	After Step 3	Final
server.port	default 8080	8081	8081	8081
spring.datasource.url	none	jdbc:mysql://localhost:3306/db	jdbc:mysql://localhost:3306/db	jdbc:mysql://localhost:3306/db
logging.level.root	default INFO	INFO	INFO	INFO

Key Moments - 2 Insights

Why does Spring Boot use application.properties when application.yml is missing?

Spring Boot checks for application.yml first. If it doesn't find it (see execution_table step 1), it looks for application.properties and loads it instead (step 2).

Can I use application.properties and application.yml together?

Yes, but application.yml has higher priority. If both exist, Spring Boot loads application.yml first and overrides properties from application.properties.

Visual Quiz - 3 Questions

Look at the execution_table, at which step does Spring Boot load the alternative config file?

A Step 3

B Step 1

C Step 2

D Step 4

💡 Hint

Check the 'Action' column for when properties are loaded.

According to variable_tracker, what is the final value of server.port?

A 8080

B 8081

C default

D none

💡 Hint

Look at the 'Final' column for server.port.

If application.yml existed, how would the execution_table change?

A Step 1 would find application.yml and load it, skipping application.properties

B Step 2 would still load application.properties

C Both files would load simultaneously

D App would fail to start

💡 Hint

Refer to concept_flow showing priority order.

Concept Snapshot

Spring Boot config files order:
1. application.yml (preferred)
2. application.properties (alternative)
If application.yml missing, properties file loads.
Properties set here configure app behavior like port, DB, logging.
Use either file format but YAML has priority.

Full Transcript

Spring Boot applications look for configuration files to set up app settings. The preferred file is application.yml. If this file is missing, Spring Boot checks for application.properties as an alternative. When application.properties is found, Spring Boot loads its key-value pairs to configure the app, such as server port, database connection, and logging levels. This process ensures the app runs with the desired settings. If both files exist, application.yml takes priority and overrides properties from application.properties. This behavior helps developers choose their preferred config format while maintaining a clear loading order.