Chapter 8. Setting custom configuration sources

Procedure

1. Create an ExampleConfigSourceProvider.java file within your project and add the following imports:

   package org.acme.config;
   
   import java.util.Collections;
   import java.util.HashMap;
   import java.util.Map;
   import java.util.Set;
   
   import org.eclipse.microprofile.config.spi.ConfigSource;
   import org.eclipse.microprofile.config.spi.ConfigSourceProvider;

2. Create a class implementing the ConfigSourceProvider interface and make sure to override its getConfigSources method to return a list of ConfigSource objects:

   The following example shows an implementation of a custom ConfigSourceProvider and a ConfigSource classes:

   public class ExampleConfigSourceProvider implements ConfigSourceProvider {
   
       private final int times = 2;
       private final String name = "example";
       private final String value = "value";
   
       @Override
       public Iterable<ConfigSource> getConfigSources(ClassLoader forClassLoader) {
           InMemoryConfigSource configSource = new InMemoryConfigSource(Integer.MIN_VALUE, "example config source");
           for (int i = 0; i < this.times; i++) {
               configSource.add(this.name + ".key" + (i + 1), this.value + (i + 1));
           }
           return Collections.singletonList(configSource);
       }
   
       private static final class InMemoryConfigSource implements ConfigSource {
   
           private final Map<String, String> values = new HashMap<>();
           private final int ordinal;
           private final String name;
   
           private InMemoryConfigSource(int ordinal, String name) {
               this.ordinal = ordinal;
               this.name = name;
           }
   
           public void add(String key, String value) {
               values.put(key, value);
           }
   
           @Override
           public Map<String, String> getProperties() {
               return values;
           }
   
           @Override
           public Set<String> getPropertyNames() {
               return values.keySet();
           }
   
           @Override
           public int getOrdinal() {
               return ordinal;
           }
   
           @Override
           public String getValue(String propertyName) {
               return values.get(propertyName);
           }
   
           @Override
           public String getName() {
               return name;
           }
       }
   }

3. Create the org.eclipse.microprofile.config.spi.ConfigSourceProvider service file in the META-INF/services/ directory.

4. Open the org.eclipse.microprofile.config.spi.ConfigSourceProvider file and add the fully qualified name of your custom ConfigSourceProvider class:

   org.acme.config.ExampleConfigSourceProvider

5. To compile the application in development mode, enter the following command from the project directory:

   ./mvnw quarkus:dev

   When you restart your application, Quarkus picks up the custom configuration provider.