Configuration beyond Spring

quarkus_and_micronaut_configuration.md

Quarkus configuration

Quarkus configuration is very similar to Spring:

• supports application.properties and application.yaml
• conventions on property names are the same: '.' as separator, kebab-case.
• supports property sources, iterating over them and getting value by name programmatically or with annotation

What's different:

• Quarkus uses smallrye-config which is implementation of microprofile-config. Annotation and feature-wise, it's similar to spring, but more explicit (reflection is discouraged)
• Property metadata can be extended with microprofile language-server extension (example)
• Doesn't support auto-binding 3rd party classes to config: requires explicit annotations and static binding.

What's (seems to be) the right approach for rich integration:

• extension, e.g. AWS S3

Micronaut configuration

Micronaut configuration is similar to Spring too:

• supports application.properties and application.yaml
• conventions on property names are the same: '.' as separator, kebab-case
• supports property sources, iterating over them and getting value by name programmatically or with annotation
• IntelliJ supports spring-configuration-metadata.json

What's different:

• Doesn't support auto-binding 3rd party classes to config: requires explicit annotations and static binding.

What's (seems to be) the right approach for rich integration:

• not clear
• AWS uses a @ConfigurationBuilder that happens to work with their typed client configuration. It depends on typed client-specific options and some duck typing (e.g. presence of build() method on annotated with @ConfigurationBuilder options)

Samples with Azure SDK

Quarkus

0. application.properties or application.yml

   az.client.application-id=123
   az.http.client.application-id=${az.client.application-id}321
   az.appconfig.endpoint=https://lmolkova-appconfig.azconfig.io
   az.appconfig-secondary.endpoint=https://lmolkova-appconfig.azconfig.io

1. Implement configuration source

   class SdkConfigurationSource implements ConfigurationSource {
   
       Map<String, String> properties;
       public SdkConfigurationSource() {
           properties = new HashMap<>();
           ConfigProvider.getConfig().getConfigSources()
                   .forEach(s -> s.getProperties()
                           .forEach((k, v) -> properties.put(k, v)));
       }
   
       @Override
       public Set<String> getChildKeys(String path) {
           if (path == null) {
               return properties.keySet();
           }
   
           return properties.keySet().stream()
                   .filter(key -> key.startsWith(path) && key.length() > path.length() && key.charAt(path.length()) == '.')
                   .collect(Collectors.toSet());
       }
   
       @Override
       public String getValue(String propertyName) {
           return ConfigProvider.getConfig().getValue(propertyName, String.class);
       }
   }

2. register builder

   public class SdkConfiguration {
     @Produces
     @ApplicationScoped
     ConfigurationBuilder sdkConfigurationBuilder() {
         return new ConfigurationBuilder(new SdkConfigurationSource()).root("az");
     }
   
     @Produces
     @ApplicationScoped
     TokenCredential defaultTokenCredential(ConfigurationBuilder sdkConfigBuilder) {
         return new DefaultAzureCredentialBuilder().configuration(sdkConfigBuilder.build()).build();
     }
   }

3. register SDK client builder

   @Produces
   @ApplicationScoped
   @DefaultBean // in case there is another one
   ConfigurationClientBuilder configurationClientBuilder(ConfigurationBuilder sdkConfigBuilder, TokenCredential tokenCredential) {
       return new ConfigurationClientBuilder()
               .credential(tokenCredential)
               .configuration(sdkConfigBuilder.buildSection("appconfig"));
   }

4. named client

   @Qualifier
   @Retention(RUNTIME)
   @Target({METHOD, FIELD})
   public @interface Secondary {
   }
   
   @Produces
   @ApplicationScoped
   @Secondary
   ConfigurationClientBuilder secondaryConfigurationClientBuilder(ConfigurationBuilder sdkConfigBuilder, TokenCredential tokenCredential) {
       return new ConfigurationClientBuilder()
               .credential(tokenCredential)
               .configuration(sdkConfigBuilder.buildSection("appconfig-secondary"));
   }

Resolving SDK builder/client

@Path("/hello")
public class GreetingResource {

    @Inject
    ConfigurationClient appconfig;


    @Inject @Secondary
    ConfigurationClient appconfigSecondary;

    @GET
    @Produces(MediaType.TEXT_PLAIN)
    public String hello() {
        return "Got configuration: " + appconfig.getConfigurationSetting("for", "bar").getValue() + ", secondary: " + appconfigSecondary.getConfigurationSetting("for", "bar").getValue();
    }
}

Micronaut

0. application.yml

   az:
     http:
       client:
         application-id: test${appid}
       logging:
         log-level: body
     appconfig:
       endpoint: https://lmolkova-appconfig.azconfig.io
     appconfig-secondary:
       endpoint: https://lmolkova-appconfig.azconfig.io

1. implement configuration source

   class SdkConfigurationSource implements ConfigurationSource {
   
       Set<String> properties;
       ApplicationContext appContext;
       public SdkConfigurationSource(ApplicationContext appContext) {
           this.properties = new HashSet<>();
           this.appContext = appContext;
           this.appContext.getEnvironment().getPropertySources().stream()
                   .forEach(source -> source.forEach(prop -> this.properties.add(prop)));
       }
   
       @Override
       public Set<String> getChildKeys(String path) {
           if (path == null) {
               return properties;
           }
   
           return properties.stream()
                   .filter(key -> key.startsWith(path) && key.length() > path.length() && key.charAt(path.length()) == '.')
                   .collect(Collectors.toSet());
       }
   
       @Override
       public String getValue(String propertyName) {
           return appContext.getProperty(propertyName, String.class).orElse(null);
       }
   }

2. register configuration builder

   @Factory
   public class SdkConfiguration {
       @Inject
       ApplicationContext applicationContext;
   
       @Singleton
       ConfigurationBuilder configurationBuilder() {
           return new ConfigurationBuilder(new SdkConfigurationSource(applicationContext)).root("az");
       }
   }

3. register SDK client builder

   @Factory
   public class AppConfiguration {
       @Inject
       ConfigurationBuilder sdkConfigurationBuilder;
   
       @Singleton
       @Named("appconfig-primary") // only needed if there is more than one client
       ConfigurationClient configurationClientBuilder(TokenCredential tokenCredential) {
           return new ConfigurationClientBuilder()
                   .credential(tokenCredential)
                   .configuration(sdkConfigurationBuilder.buildSection("appconfig"))
                   .buildClient();
       }
   
       @Singleton
       TokenCredential defaultTokenCredential() {
           return new DefaultAzureCredentialBuilder().configuration(sdkConfigurationBuilder.build()).build();
       }
   }

4. named client

   @Singleton
   @Named("appconfig-secondary")
   ConfigurationClient configurationSecondaryClientBuilder(TokenCredential tokenCredential) {
       return new ConfigurationClientBuilder()
               .credential(tokenCredential)
               .configuration(sdkConfigurationBuilder.buildSection("appconfig-secondary"))
               .buildClient();
   }

Resolving SDK builder/client

@Controller("/hello")
public class HelloController {

    @Inject
    @Named("appconfig-primary")
    ConfigurationClient appconfig;

    @Inject
    @Named("appconfig-secondary")
    ConfigurationClient appconfigSecondary;

    @Get
    @Produces(MediaType.TEXT_PLAIN)
    public String index() {
        return "Got configuration: " + appconfig.getConfigurationSetting("foo", "bar").getValue();
    }
}