How to convert from application.properties to application.yml in Spring Boot?

I have a very simple Spring Boot app and I have application.properties, and now I want to move to application.yml

This is the application.yml file:

spring:
    datasource:
        url: jdbc:mysql://localhost:3306/employee_directory
        username: student
        password: Password123

So I've deleted application.properties file and I've written the application.yml file. If I run the app I get this exception:

   20:31:22.446 [restartedMain] ERROR org.springframework.boot.SpringApplication - Application run failed
java.lang.IllegalStateException: Failed to load property source from location 'classpath:/application.yml'
    at org.springframework.boot.context.config.ConfigFileApplicationListener$Loader.load(ConfigFileApplicationListener.java:524)
    at org.springframework.boot.context.config.ConfigFileApplicationListener$Loader.loadForFileExtension(ConfigFileApplicationListener.java:473)
    at org.springframework.boot.context.config.ConfigFileApplicationListener$Loader.load(ConfigFileApplicationListener.java:443)
    at org.springframework.boot.context.config.ConfigFileApplicationListener$Loader.lambda$null$6(ConfigFileApplicationListener.java:425)
    at java.lang.Iterable.forEach(Iterable.java:75)
    at org.springframework.boot.context.config.ConfigFileApplicationListener$Loader.lambda$load$7(ConfigFileApplicationListener.java:425)
    at java.lang.Iterable.forEach(Iterable.java:75)
    at org.springframework.boot.context.config.ConfigFileApplicationListener$Loader.load(ConfigFileApplicationListener.java:422)
    at org.springframework.boot.context.config.ConfigFileApplicationListener$Loader.load(ConfigFileApplicationListener.java:321)
    at org.springframework.boot.context.config.ConfigFileApplicationListener.addPropertySources(ConfigFileApplicationListener.java:202)
    at org.springframework.boot.context.config.ConfigFileApplicationListener.postProcessEnvironment(ConfigFileApplicationListener.java:186)
    at org.springframework.boot.context.config.ConfigFileApplicationListener.onApplicationEnvironmentPreparedEvent(ConfigFileApplicationListener.java:176)
    at org.springframework.boot.context.config.ConfigFileApplicationListener.onApplicationEvent(ConfigFileApplicationListener.java:164)
    at org.springframework.context.event.SimpleApplicationEventMulticaster.doInvokeListener(SimpleApplicationEventMulticaster.java:172)
    at org.springframework.context.event.SimpleApplicationEventMulticaster.invokeListener(SimpleApplicationEventMulticaster.java:165)
    at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:139)
    at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:127)
    at org.springframework.boot.context.event.EventPublishingRunListener.environmentPrepared(EventPublishingRunListener.java:75)
    at org.springframework.boot.SpringApplicationRunListeners.environmentPrepared(SpringApplicationRunListeners.java:53)
    at org.springframework.boot.SpringApplication.prepareEnvironment(SpringApplication.java:340)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:304)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1213)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1202)
    at com.dgs.springboot.SpringBootRESTJPA.SpringBootRestJPAApplication.main(SpringBootRestJPAApplication.java:10)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.springframework.boot.devtools.restart.RestartLauncher.run(RestartLauncher.java:49)
Caused by: org.yaml.snakeyaml.scanner.ScannerException: while scanning for the next token
found character '\t(TAB)' that cannot start any token. (Do not use \t(TAB) for indentation)
 in 'reader', line 2, column 1:
        datasource:
    ^

    at org.yaml.snakeyaml.scanner.ScannerImpl.fetchMoreTokens(ScannerImpl.java:419)
    at org.yaml.snakeyaml.scanner.ScannerImpl.checkToken(ScannerImpl.java:227)
    at org.yaml.snakeyaml.parser.ParserImpl$ParseBlockMappingValue.produce(ParserImpl.java:586)
    at org.yaml.snakeyaml.parser.ParserImpl.peekEvent(ParserImpl.java:158)
    at org.yaml.snakeyaml.parser.ParserImpl.checkEvent(ParserImpl.java:148)
    at org.yaml.snakeyaml.composer.Composer.composeNode(Composer.java:124)
    at org.yaml.snakeyaml.composer.Composer.composeValueNode(Composer.java:236)
    at org.yaml.snakeyaml.composer.Composer.composeMappingChildren(Composer.java:227)
    at org.yaml.snakeyaml.composer.Composer.composeMappingNode(Composer.java:215)
    at org.yaml.snakeyaml.composer.Composer.composeNode(Composer.java:144)
    at org.yaml.snakeyaml.composer.Composer.getNode(Composer.java:85)
    at org.yaml.snakeyaml.constructor.BaseConstructor.getData(BaseConstructor.java:123)
    at org.yaml.snakeyaml.Yaml$1.next(Yaml.java:547)
    at org.springframework.beans.factory.config.YamlProcessor.process(YamlProcessor.java:160)
    at org.springframework.beans.factory.config.YamlProcessor.process(YamlProcessor.java:134)
    at org.springframework.boot.env.OriginTrackedYamlLoader.load(OriginTrackedYamlLoader.java:75)
    at org.springframework.boot.env.YamlPropertySourceLoader.load(YamlPropertySourceLoader.java:49)
    at org.springframework.boot.context.config.ConfigFileApplicationListener$Loader.loadDocuments(ConfigFileApplicationListener.java:542)
    at org.springframework.boot.context.config.ConfigFileApplicationListener$Loader.load(ConfigFileApplicationListener.java:497)
    ... 28 common frames omitted

I think I need to make other modification to my code to use this application.yml file but I don't know what to do?

This is pom.xml:

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.6.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.dgs.springboot</groupId>
    <artifactId>SpringBootRESTHibernate</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>SpringBootRESTHibernate</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>1.8</java.version>
        <!-- Add work around for Eclipse bug -->
        <maven-jar-plugin.version>3.1.1</maven-jar-plugin.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>

        <dependency>
          <groupId>org.projectlombok</groupId>
          <artifactId>lombok</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <!-- This is used for packaging and running our app -->
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

Any feedback will be appreciated. Thank you!

Solution 1:

I built an online conversion tool (https://env.simplestep.ca/) that converts between spring boot yaml, properties and environment variables--using spring boot's relaxed binding rules

Solution 2:

Check if you are using tabs for indentation. This is not permitted by the YAML spec:

To maintain portability, tab characters must not be used in indentation, since different systems treat tabs differently. Note that most modern editors may be configured so that pressing the tab key results in the insertion of an appropriate number of spaces.

Solution 3:

You can use the command line tool props2yaml for generic automatic (and correct) translation from properties to yaml.