Spring Vault: Why @VaultPropertySource not getting highest precedence?

In Spring-based applications, @VaultPropertySource is a powerful annotation that allows developers to externalize configuration properties from HashiCorp’s Vault. However, there have been instances where @VaultPropertySource does not get the highest precedence, leading to unexpected behavior in the application.

Understanding Property Source Ordering in Spring

In Spring, property sources are ordered based on their precedence. The order of precedence determines which property source takes priority over others. By default, Spring uses the following order:

1. CommandLine property sources
System property sources
2. Environment property sources
3. application.properties files
4. application.yml files
5. Profile-specific application.properties files
6. Profile-specific application.yml files

The Role of @VaultPropertySource in Property Source Ordering

@VaultPropertySource is a custom property source that allows Spring to retrieve properties from Vault. However, by default, @VaultPropertySource has a lower precedence than the default property sources listed above. This means that if there are duplicate properties in both the Vault and the default property sources, the default property sources will take precedence.

Solution: Overriding the Precedence of @VaultPropertySource

To give @VaultPropertySource the highest precedence, you need to explicitly configure the property source ordering in your Spring application. You can do this by creating a custom PropertySourceLocator bean and overriding the default property source ordering.

Here’s an example:

@Bean
public static PropertySourceLocator propertySourceLocator() {
    return new VaultPropertySourceLocator();
}

public class VaultPropertySourceLocator implements PropertySourceLocator {
    @Override
    public List<PropertySource> locate(Environment environment) {
        List<PropertySource> propertySources = new ArrayList<>();
        propertySources.add(new VaultPropertySource("vault", "http://localhost:8200"));
        // Add other property sources with lower precedence
        propertySources.add(new PropertiesPropertySource("applicationProperties", new Properties()));
        return propertySources;
    }
}

By overriding the property source ordering, you can ensure that @VaultPropertySource gets the highest precedence, and your application retrieves properties from Vault as expected.

Remember to adjust the precedence of other property sources according to your application’s requirements.

Frequently Asked Question

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