Add updatable config source

spi/.gitignore

@@ -1,3 +1,5 @@
+hub.properties
+
 #Maven
 target/
 pom.xml.tag

spi/README.md

@@ -8,7 +8,7 @@ If you want to learn more about Quarkus, please visit its website: https://quark
 
 You can run your application in dev mode that enables live coding using:
 ```shell script
-mvn compile quarkus:dev
+mvn compile quarkus:dev -Dhub.config.path=hub.properties
 ```
 
 > **_NOTE:_**  Quarkus now ships with a Dev UI, which is available in dev mode only at http://localhost:8080/q/dev/.

spi/src/main/java/org/cryptomator/hub/config/HubConfig.java

@@ -0,0 +1,79 @@
+package org.cryptomator.hub.config;
+
+import org.eclipse.microprofile.config.spi.ConfigSource;
+import org.jboss.logging.Logger;
+
+import javax.enterprise.inject.Vetoed;
+import java.nio.file.Path;
+import java.util.Properties;
+import java.util.Set;
+
+@Vetoed
+public class HubConfig implements ConfigSource {
+
+	private static final Logger LOG = Logger.getLogger(HubConfig.class);
+	private static final String HUB_CONFIGSOURCE_NAME = "HubConfig";
+	private static final String HUB_CONFIGPATH_PROPERTY_KEY = "hub.config.path";
+
+	private final HubConfigPersistence persistence;
+	private final Properties config;
+
+	public HubConfig() {
+		var configPath = System.getProperty(HUB_CONFIGPATH_PROPERTY_KEY);
+		if (configPath == null) {
+			throw new IllegalStateException("Property " + HUB_CONFIGPATH_PROPERTY_KEY + " not set.");
+		}
+
+		LOG.info("Hub config persists to " + configPath);
+		this.config = new Properties();
+		this.persistence = new HubConfigPersistence(Path.of(configPath));
+
+		persistence.load(config);
+	}
+
+	@Override
+	public Set<String> getPropertyNames() {
+		return config.stringPropertyNames();
+	}
+
+	@Override
+	// for default sources and their precedence see https://quarkus.io/guides/config-reference#configuration-sources
+	public int getOrdinal() {
+		return 270;
+	}
+
+	@Override
+	public String getValue(String key) {
+		return config.getProperty(key);
+	}
+
+	@Override
+	public String getName() {
+		return HUB_CONFIGSOURCE_NAME;
+	}
+
+	public synchronized void setProperty(Key key, String value) {
+		String oldVal = (String) config.setProperty(key.toString(), value);
+		if (oldVal == null || !oldVal.equals(value)) {
+			persistence.persist(config);
+		}
+	}
+
+	public enum Key {
+
+		//TODO: replace by real property key
+		DUMMY_VALUE("dummy.value");
+
+		private final String actualKeyString;
+
+		Key(String actualKeyString) {
+			this.actualKeyString = actualKeyString;
+		}
+
+		@Override
+		public String toString() {
+			return actualKeyString;
+		}
+	}
+
+}

spi/src/main/java/org/cryptomator/hub/config/HubConfigPersistence.java

@@ -0,0 +1,43 @@
+package org.cryptomator.hub.config;
+
+import org.jboss.logging.Logger;
+
+import java.io.IOException;
+import java.io.UncheckedIOException;
+import java.nio.file.Files;
+import java.nio.file.NoSuchFileException;
+import java.nio.file.Path;
+import java.nio.file.StandardOpenOption;
+import java.util.Properties;
+
+class HubConfigPersistence {
+
+	private static final Logger LOG = Logger.getLogger(HubConfigPersistence.class);
+	private static final String HUB_CONFIG_DESCRIPTION = "Cryptomator Hub configuration persistence file";
+
+	private final Path configPath;
+
+	HubConfigPersistence(Path configPath) {
+		this.configPath = configPath;
+	}
+
+	synchronized void persist(Properties properties) {
+		try (var out = Files.newOutputStream(configPath, StandardOpenOption.CREATE, StandardOpenOption.TRUNCATE_EXISTING)) {
+			properties.store(out, HUB_CONFIG_DESCRIPTION);
+		} catch (IOException e) {
+			throw new UncheckedIOException("Unable to persist Hub config to " + configPath, e);
+		}
+	}
+
+	synchronized void load(Properties prop) {
+		try (var in = Files.newInputStream(configPath, StandardOpenOption.READ)) {
+			prop.load(in);
+		} catch (NoSuchFileException e) {
+			LOG.debugf("No hub config file found at %s.", configPath);
+		} catch (IOException e) {
+			LOG.warn(String.format("Unable to read hub config from %s, creating empty.", configPath), e);
+		}
+	}
+
+
+}

spi/src/main/java/org/cryptomator/hub/config/HubConfigProducer.java

@@ -0,0 +1,20 @@
+package org.cryptomator.hub.config;
+
+import org.eclipse.microprofile.config.ConfigProvider;
+
+import javax.enterprise.context.ApplicationScoped;
+import javax.enterprise.inject.Produces;
+import java.util.stream.StreamSupport;
+
+public class HubConfigProducer {
+
+	@Produces
+	@ApplicationScoped
+	public static HubConfig getInstance() {
+		return (HubConfig) StreamSupport.stream(ConfigProvider.getConfig().getConfigSources().spliterator(), false)
+				.filter(s -> s instanceof HubConfig)
+				.findFirst()
+				.get();
+	}
+
+}

spi/src/main/resources/META-INF/services/org.eclipse.microprofile.config.spi.ConfigSource

@@ -0,0 +1 @@
+org.cryptomator.hub.config.HubConfig