Add EZKV maven plugin.

ezkv-maven-plugin/pom.xml

@@ -0,0 +1,37 @@
+<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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+  <modelVersion>4.0.0</modelVersion>
+  <parent>
+    <groupId>io.jstach.ezkv</groupId>
+    <artifactId>ezkv-maven-parent</artifactId>
+    <version>0.3.0-SNAPSHOT</version>
+  </parent>
+  <artifactId>ezkv-maven-plugin</artifactId>
+  <packaging>maven-plugin</packaging>
+  <properties>
+    <doc.resources>../</doc.resources>
+    <parent.root>${basedir}/..</parent.root>
+    <maven.javadoc.skip>false</maven.javadoc.skip>
+  </properties>
+  <dependencies>
+    <dependency>
+      <groupId>io.jstach.ezkv</groupId>
+      <artifactId>ezkv-kvs</artifactId>
+    </dependency>
+    <dependency>
+      <groupId>org.apache.maven</groupId>
+      <artifactId>maven-plugin-api</artifactId>
+    </dependency>
+    <dependency>
+      <groupId>org.apache.maven</groupId>
+      <artifactId>maven-core</artifactId>
+    </dependency>
+    <dependency>
+      <groupId>org.apache.maven.plugin-tools</groupId>
+      <artifactId>maven-plugin-annotations</artifactId>
+      <scope>provided</scope>
+      <version>3.15.1</version>
+    </dependency>
+  </dependencies>
+</project>

ezkv-maven-plugin/src/main/java/io/jstach/ezkv/maven/ReadConfigMojo.java

@@ -0,0 +1,185 @@
+package io.jstach.ezkv.maven;
+
+import java.io.IOException;
+import java.util.Collections;
+import java.util.Properties;
+import java.util.Set;
+
+import org.apache.maven.execution.MavenSession;
+import org.apache.maven.plugin.AbstractMojo;
+import org.apache.maven.plugin.MojoExecutionException;
+import org.apache.maven.plugin.MojoFailureException;
+import org.apache.maven.plugin.logging.Log;
+import org.apache.maven.plugins.annotations.LifecyclePhase;
+import org.apache.maven.plugins.annotations.Mojo;
+import org.apache.maven.plugins.annotations.Parameter;
+import org.apache.maven.project.MavenProject;
+import org.jspecify.annotations.Nullable;
+
+import io.jstach.ezkv.kvs.KeyValuesEnvironment;
+import io.jstach.ezkv.kvs.KeyValuesSystem;
+import io.jstach.ezkv.kvs.Variables;
+
+/**
+ * This plugin is similar to <a href=
+ * "https://www.mojohaus.org/properties-maven-plugin/">properties-maven-plugin</a> except
+ * that it will use EZKV to load the properties. Unlike the Codehaus properties plugin
+ * this plugin allows chain loading of config.
+ * <p>
+ * However like the Codehaus properties plugin this plugin has the following limitations:
+ * </p>
+ * <p>
+ * This plugin (as all other) is executed in the later phase - when project model is
+ * already build in memory.
+ * </p>
+ * <p>
+ * So properties read from external files by this plugin can not by used in project
+ * definitions in items like {@code <goal>}, {@code <version>} and so on.
+ * </p>
+ * <p>
+ * Properties read by plugin in one module are not propagated to other modules or child
+ * projects.
+ * </p>
+ * <p>
+ * Properties are only available for other plugins in runtime like for
+ * maven-resource-plugin for filtering resources.
+ * </p>
+ */
+@Mojo(name = "read-config", defaultPhase = LifecyclePhase.NONE, requiresProject = true, threadSafe = true)
+public class ReadConfigMojo extends AbstractMojo {
+
+	@Parameter(defaultValue = "${project}", readonly = true, required = true)
+	private @Nullable MavenProject project;
+
+	@Parameter(defaultValue = "${session}", readonly = true, required = true)
+	private @Nullable MavenSession session;
+
+	/**
+	 * Maven will call this constructor.
+	 */
+	public ReadConfigMojo() {
+	}
+
+	/**
+	 * The URLs that will be used when reading properties. These may be non-standard URLs
+	 * of the form <code>classpath:com/company/resource.properties</code>. Note that the
+	 * type is not <code>URL</code> for this reason and therefore will be explicitly
+	 * checked by this Mojo.
+	 */
+	@Parameter(required = true)
+	private String[] urls = new String[0];
+
+	/**
+	 * Default scope for test access.
+	 * @param urls The URLs to set for tests.
+	 */
+	public void setUrls(String[] urls) {
+		if (urls == null) {
+			this.urls = null;
+		}
+		else {
+			this.urls = new String[urls.length];
+			System.arraycopy(urls, 0, this.urls, 0, urls.length);
+		}
+	}
+
+	private static <T> T requireInjected(@Nullable T obj, String message) throws MojoExecutionException {
+		if (obj == null) {
+			throw new MojoExecutionException("Missing injection '" + message + "'");
+		}
+		return obj;
+	}
+
+	@Override
+	public void execute() throws MojoExecutionException, MojoFailureException {
+		String[] _urls = this.urls;
+		if (_urls == null || _urls.length < 1) {
+			throw new MojoExecutionException("urls not set");
+		}
+		var log = getLog();
+		var logger = new MavenLogger(log);
+		var session = requireInjected(this.session, "session");
+		var project = requireInjected(this.project, "project");
+		KeyValuesEnvironment env = new KeyValuesEnvironment() {
+			@Override
+			public Properties getSystemProperties() {
+				return session.getSystemProperties();
+			}
+
+			@Override
+			public KeyValuesEnvironment.Logger getLogger() {
+				return logger;
+			}
+		};
+		var loader = KeyValuesSystem.builder()
+			.useServiceLoader() //
+			.environment(env) //
+			.build()
+			.loader();
+
+		final Variables missingSystemPropeties = new Variables() {
+			final Set<String> requiredSystemProperties = Collections.singleton("user.home");
+
+			@Override
+			public @Nullable String getValue(String key) {
+				if (requiredSystemProperties.contains(key)) {
+					getLog().info("Using real system property as it was not in maven's system properties. key=" + key);
+					return System.getProperty(key);
+				}
+				return null;
+			}
+		};
+		loader.add(missingSystemPropeties);
+		loader.variables(Variables::ofSystemEnv);
+		loader.variables(Variables::ofSystemProperties);
+		Properties originalProperties = project.getProperties();
+		// TODO maybe a bad idea?
+		loader.add(originalProperties::getProperty);
+
+		for (String url : _urls) {
+			loader.add(url);
+		}
+		try {
+			var kvs = loader.load().memoize();
+			if (log.isDebugEnabled()) {
+				getLog().debug("Found keys: " + kvs);
+			}
+			// TODO should we do some sort of lock here?
+			// Technically properties is synchronized
+			for (var kv : kvs) {
+				originalProperties.put(kv.key(), kv.value());
+			}
+
+		}
+		catch (IOException e) {
+			throw new MojoExecutionException("failed to load config", e);
+		}
+
+	}
+
+	record MavenLogger(Log log) implements KeyValuesEnvironment.Logger {
+
+		@Override
+		public void debug(String message) {
+			if (log.isDebugEnabled()) {
+				log.debug(message);
+			}
+		}
+
+		@Override
+		public void info(String message) {
+			if (log.isInfoEnabled()) {
+				log.info(message);
+			}
+		}
+
+		@Override
+		public void warn(String message) {
+			if (log.isWarnEnabled()) {
+				log.warn(message);
+			}
+		}
+
+	}
+
+}

ezkv-maven-plugin/src/main/java/io/jstach/ezkv/maven/package-info.java

@@ -0,0 +1,9 @@
+/**
+ * EZKV Maven Plugin to load configuration during Maven build and is analogous to
+ * <a href="https://www.mojohaus.org/properties-maven-plugin/">properties-maven-plugin</a>
+ * except that it will use EZKV to load the properties. Unlike the Codehaus properties
+ * plugin this plugin allows chain loading of config.
+ * @see io.jstach.ezkv.maven.ReadConfigMojo
+ */
+@org.jspecify.annotations.NullMarked
+package io.jstach.ezkv.maven;

pom.xml

@@ -85,6 +85,13 @@
         <groupId>org.apache.maven</groupId>
         <artifactId>maven-core</artifactId>
         <version>${maven.core.version}</version>
+        <scope>provided</scope>
+      </dependency>
+      <dependency>
+        <groupId>org.apache.maven</groupId>
+        <artifactId>maven-plugin-api</artifactId>
+        <version>${maven.core.version}</version>
+        <scope>provided</scope>
       </dependency>
       <dependency>
         <groupId>org.jspecify</groupId>
@@ -977,5 +984,6 @@
     <module>ezkv-boot</module>
     <module>ezkv-dotenv</module>
     <module>ezkv-json5</module>
+    <module>ezkv-maven-plugin</module>
   </modules>
 </project>