Make stdin conditional

doc/overview.html

@@ -438,6 +438,34 @@ <h4 id="uri-schemas-stdin">URI schema: <code>stdin</code></h4>
 <p>The above example is particularly useful for passwords, similar to 
 <a href="https://docs.docker.com/reference/cli/docker/login/#password-stdin" target="_blank">how Docker handles passwords from stdin</a>.</p>
 
+
+Stdin is retrieved from {@link io.jstach.ezkv.kvs.KeyValuesEnvironment#getStandardInput()}.
+Because checking stdin will block an application one must enable reading from it which is done
+by either:
+<ol>
+<li> Checking resource parameter of {@value io.jstach.ezkv.kvs.KeyValuesResource#SCHEMA_STDIN_PARAM} is <code>true</code>.
+</li>
+<li>Setting {@value io.jstach.ezkv.kvs.KeyValuesResource#SCHEMA_STDIN_MAIN_ARG_PARAM} to 
+{@linkplain io.jstach.ezkv.kvs.KeyValuesEnvironment#getMainArgs() command line argument} to check if present.
+</li>
+<li>
+Relying on the default which will check "<code>--</code>" + {@link io.jstach.ezkv.kvs.KeyValuesResource#name()}
+command line argument is present.
+</li>
+</ol>
+
+{@snippet lang=properties :
+# will be enabled if --dbpassword is passed on the command line
+# since dbpassword is the resource name.
+_load_dbpassword=stdin:///db.password?_flag=sensitive,optional
+# specify that the "--password" command line arg is required
+_load_stdin=stdin:///db.password?_param_stdin_arg=--password&_flag=sensitive
+# alternatively one can do:
+_load_stdin=stdin:///?_p_stdin=${some_other_variable}
+# which will be enabled if some_other_variable evalutes to 'true'
+}
+
+
 <h4 id="uri-schema-profile">URI schema: <code>profile.</code></h4>
 <p><strong>Note:</strong> This schema may be renamed to <code>profiles</code> in the future.</p>
 

ezkv-kvs/src/main/java/io/jstach/ezkv/kvs/DefaultKeyValuesLoaderFinder.java

@@ -12,7 +12,6 @@
 import java.nio.file.Path;
 import java.util.ArrayList;
 import java.util.Arrays;
-import java.util.Collections;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Locale;
@@ -179,6 +178,33 @@ protected KeyValues load(LoaderContext context, KeyValuesResource resource) thro
 	STDIN(KeyValuesResource.SCHEMA_STDIN) {
 		@Override
 		protected KeyValues load(LoaderContext context, KeyValuesResource resource) throws IOException {
+
+			boolean enabled;
+
+			String stdinEnabled = resource.parameters().getValue(KeyValuesResource.SCHEMA_STDIN_PARAM);
+
+			if (stdinEnabled != null) {
+				enabled = Boolean.parseBoolean(stdinEnabled);
+			}
+			else {
+				String mainArgName = resource.parameters().getValue(KeyValuesResource.SCHEMA_STDIN_MAIN_ARG_PARAM);
+
+				if (mainArgName == null) {
+					mainArgName = "--" + resource.name();
+				}
+				String argName = mainArgName;
+
+				enabled = Arrays.asList(context.environment().getMainArgs())
+					.stream()
+					.filter(s -> s.equals(argName))
+					.findFirst()
+					.isPresent();
+			}
+
+			if (!enabled) {
+				throw new FileNotFoundException("stdin not enabled.");
+			}
+
 			var builder = KeyValues.builder(resource);
 
 			BiConsumer<String, String> consumer = builder::add;

ezkv-kvs/src/main/java/io/jstach/ezkv/kvs/KeyValuesEnvironment.java

@@ -9,7 +9,10 @@
 import java.nio.file.FileSystem;
 import java.nio.file.FileSystems;
 import java.nio.file.Path;
+import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.Collections;
+import java.util.List;
 import java.util.Map;
 import java.util.Properties;
 import java.util.Random;
@@ -34,6 +37,7 @@
  */
 public interface KeyValuesEnvironment {
 
+	// TODO remove
 	/**
 	 * If the loader builder is not passed any resources this resource will be used.
 	 * @return default resource is <code>classpath:/boot.properties</code>
@@ -47,7 +51,32 @@ default KeyValuesResource defaultResource() {
 	 * @return an array of main method arguments
 	 */
 	default @NonNull String[] getMainArgs() {
-		return new @NonNull String[] {};
+		var logger = getLogger();
+		logger.warn("Main Args were requested but not provided. Using fallback 'sun.java.command'");
+		String value = getSystemProperties().getProperty("sun.java.command");
+		if (value == null) {
+			throw new IllegalStateException("Cannot get main args from 'sun.java.command' as it was not provided");
+		}
+		return fallbackMainArgs(value);
+	}
+
+	private static @NonNull String[] fallbackMainArgs(String sunJavaCommandValue) {
+
+		// Use fallback by extracting from system property
+		String command = sunJavaCommandValue;
+		if (!command.isEmpty()) {
+			// Split command into components (main class/jar is the first token)
+			List<String> components = new ArrayList<>(Arrays.asList(command.split("\\s+")));
+			// Remove the first element (main class or jar)
+			if (!components.isEmpty()) {
+				components.remove(0);
+			}
+			// Return remaining as the main args
+			return components.toArray(new @NonNull String[0]);
+		}
+
+		// Return an empty array if no arguments are available
+		return new String[0];
 	}
 
 	/**
@@ -356,16 +385,15 @@ public void warn(String message) {
 
 }
 
-final class DefaultKeyValuesEnvironment implements KeyValuesEnvironment {
-
-	// private static final ThreadLocal<Logger> threadLocal = new
-	// ThreadLocal<>();
-	//
-	// static Logger localLogger() {
-	// var logger = threadLocal.get();
-	// if (logger == null) {
-	// return NoOpLogger.NOPLOGGER;
-	// }
-	// }
+record DefaultKeyValuesEnvironment(@NonNull String @Nullable [] mainArgs) implements KeyValuesEnvironment {
+
+	@Override
+	public @NonNull String[] getMainArgs() {
+		var args = mainArgs;
+		if (args == null) {
+			return KeyValuesEnvironment.super.getMainArgs();
+		}
+		return args;
+	}
 
 }

ezkv-kvs/src/main/java/io/jstach/ezkv/kvs/KeyValuesResource.java

@@ -486,17 +486,49 @@ public sealed interface KeyValuesResource extends NamedKeyValuesSource, KeyValue
 	 * </p>
 	 * <code>stdin:///</code> can also bind the input content, parsed as a UTF-8 string,
 	 * to the key provided in the URI path.
+	 * <p>
+	 * Stdin is retrieved from {@link KeyValuesEnvironment#getStandardInput()}.
+	 * Because checking stdin will block an application one must enable reading from it which is done
+	 * by either:
+	 * <ol>
+	 * <li> Checking resource parameter of {@value #SCHEMA_STDIN_PARAM} is <code>true</code>.
+	 * </li>
+	 * <li>Setting {@value #SCHEMA_STDIN_MAIN_ARG_PARAM} to 
+	 * {@linkplain KeyValuesEnvironment#getMainArgs() command line argument} to check if present.
+	 * </li>
+	 * <li>
+	 * Relying on the default which will check <code>--</code> {@link KeyValuesResource#name()}
+	 * command line argument is present.
+	 * </li>
+	 * </ol>
 	 *
 	 * {@snippet lang=properties :
+	 * # will be enabled if --stdin is passed on the command line
+	 * # since stdin in is the resource name.
 	 * _load_stdin=stdin:///db.password?_flag=sensitive,optional
+	 * # alternatively one can do:
+	 * _load_stdin=stdin:///?_p_stdin=${some_other_variable}
 	 * }
-	 *
-	 * Stdin is retrieved from {@link KeyValuesEnvironment#getStandardInput()}.
-	 *
+	 * @see #SCHEMA_STDIN_PARAM
+	 * @see #SCHEMA_STDIN_MAIN_ARG_PARAM
+	 * @see KeyValuesEnvironment#getMainArgs()
 	 */
 	// @formatter:on
 	public static final String SCHEMA_STDIN = "stdin";
 
+	/**
+	 * Resource parameter to enable stdin.
+	 * @see #SCHEMA_STDIN
+	 */
+	public static final String SCHEMA_STDIN_PARAM = "stdin";
+
+	/**
+	 * Resource parameter to decide what command line argument should be present to allow
+	 * reading from stdin.
+	 * @see #SCHEMA_STDIN
+	 */
+	public static final String SCHEMA_STDIN_MAIN_ARG_PARAM = "stdin_arg";
+
 	/**
 	 * Will load multiple resources based on a CSV of profiles where the profile name
 	 * replaces part of the URI.

ezkv-kvs/src/main/java/io/jstach/ezkv/kvs/KeyValuesSystem.java

@@ -5,10 +5,12 @@
 import java.util.Collections;
 import java.util.Comparator;
 import java.util.List;
+import java.util.Objects;
 import java.util.Optional;
 import java.util.ServiceLoader;
 import java.util.function.Function;
 
+import org.jspecify.annotations.NonNull;
 import org.jspecify.annotations.Nullable;
 
 import io.jstach.ezkv.kvs.KeyValuesServiceProvider.KeyValuesFilter;
@@ -106,13 +108,28 @@ default void close() {
 	/**
 	 * Returns a default implementation of {@code KeyValuesSystem} configured with
 	 * standard settings and a ServiceLoader based on {@link KeyValuesServiceProvider} and
-	 * its classloader.
+	 * its classloader. If possible prefer {@link #defaults(String[])} to provide command
+	 * line arguments.
 	 * @return the default {@code KeyValuesSystem} instance
 	 */
 	public static KeyValuesSystem defaults() {
 		return builder().useServiceLoader().build();
 	}
 
+	/**
+	 * Returns a default implementation of {@code KeyValuesSystem} configured with
+	 * standard settings and a ServiceLoader based on {@link KeyValuesServiceProvider} and
+	 * its classloader.
+	 * @param mainArgs arguments that come from
+	 * <code>public static void main(String [] args)</code>.
+	 * @return the default {@code KeyValuesSystem} instance
+	 */
+	public static KeyValuesSystem defaults(@NonNull String[] mainArgs) {
+		Objects.requireNonNull(mainArgs);
+		var env = new DefaultKeyValuesEnvironment(mainArgs);
+		return builder().environment(env).useServiceLoader().build();
+	}
+
 	/**
 	 * Creates and returns a new {@link Builder} for constructing customized
 	 * {@code KeyValuesSystem} instances.
@@ -240,7 +257,7 @@ public Builder useServiceLoader() {
 		public KeyValuesSystem build() {
 			var environment = this.environment;
 			if (environment == null) {
-				environment = new DefaultKeyValuesEnvironment();
+				environment = new DefaultKeyValuesEnvironment(null);
 			}
 			/*
 			 * We copy as we are about to use the service loader to add more entries and

ezkv-kvs/src/test/java/io/jstach/ezkv/kvs/KeyValuesSystemTest.java

@@ -3,8 +3,10 @@
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.fail;
 
+import java.io.ByteArrayInputStream;
 import java.io.FileNotFoundException;
 import java.io.IOException;
+import java.io.InputStream;
 import java.io.PrintStream;
 import java.net.URI;
 import java.nio.file.Path;
@@ -15,6 +17,7 @@
 import java.util.Properties;
 import java.util.stream.Collectors;
 
+import org.jspecify.annotations.NonNull;
 import org.junit.jupiter.api.Test;
 
 import io.jstach.ezkv.kvs.KeyValuesEnvironment.Logger;
@@ -45,6 +48,10 @@ void testLoader() throws FileNotFoundException, IOException {
 
 		var logger = new TestLogger();
 
+		String stdin = """
+				stdin_password=guest
+				""";
+
 		var environment = new KeyValuesEnvironment() {
 			@Override
 			public Properties getSystemProperties() {
@@ -56,6 +63,16 @@ public Logger getLogger() {
 				return logger;
 			}
 
+			@Override
+			public InputStream getStandardInput() {
+				return new ByteArrayInputStream(stdin.getBytes());
+			}
+
+			@Override
+			public @NonNull String[] getMainArgs() {
+				return new String[] { "--passwords" };
+			}
+
 		};
 		var system = KeyValuesResource.builder(URI.create("system:///"))
 			.name("system")
@@ -93,6 +110,7 @@ public Logger getLogger() {
 			.add(system)
 			.add("classpath:/test-props/testLoader.properties")
 			.add("classpaths:/classpathstar.properties")
+			.add("stdin:///?_p_stdin_arg=--passwords&_mime=properties&_flag=sensitive")
 			.add("extra", KeyValues.builder().add(map.entrySet()).build())
 			.load();
 
@@ -113,6 +131,7 @@ public Logger getLogger() {
 					sensitive_ab=REDACTED
 					mypassword=REDACTED
 					classpathstar=ezkv
+					stdin_password=REDACTED
 					fromMap1=1
 					fromMap2=2
 					]
@@ -135,6 +154,7 @@ public Logger getLogger() {
 					sensitive_ab=ab
 					mypassword=1.2.3.4.5
 					classpathstar=ezkv
+					stdin_password=guest
 					fromMap1=1
 					fromMap2=2
 									""";
@@ -162,6 +182,7 @@ public Logger getLogger() {
 					KeyValue[key='sensitive_ab', raw='REDACTED', expanded='REDACTED', source=Source[uri=classpath:/test-props/testLoader-sensitive.properties, reference=[key='_load_luggage', in='classpath:/test-props/testLoader.properties'], index=2]]
 					KeyValue[key='mypassword', raw='REDACTED', expanded='REDACTED', source=Source[uri=classpath:/test-props/testLoader-sensitive.properties, reference=[key='_load_luggage', in='classpath:/test-props/testLoader.properties'], index=3]]
 					KeyValue[key='classpathstar', raw='ezkv', expanded='ezkv', source=Source[uri=file:{{CWD}}/target/test-classes/classpathstar.properties, reference=[key='_load_root30', in='classpaths:/classpathstar.properties'], index=1]]
+					KeyValue[key='stdin_password', raw='REDACTED', expanded='REDACTED', source=Source[uri=stdin:///, index=1]]
 					KeyValue[key='fromMap1', raw='1', expanded='1', source=Source[uri=null:///extra, index=0]]
 					KeyValue[key='fromMap2', raw='2', expanded='2', source=Source[uri=null:///extra, index=0]]
 					"""
@@ -204,6 +225,8 @@ public Logger getLogger() {
 					[INFO ] Loaded  uri='classpaths:/classpathstar.properties'
 					[DEBUG] Loading uri='file:{{CWD}}/target/test-classes/classpathstar.properties' flags=[NO_LOAD_CHILDREN] specified with key: '_load_root30' in uri='classpaths:/classpathstar.properties'
 					[INFO ] Loaded  uri='file:{{CWD}}/target/test-classes/classpathstar.properties' flags=[NO_LOAD_CHILDREN]
+					[DEBUG] Loading uri='stdin:///' flags=[SENSITIVE]
+					[INFO ] Loaded  uri='stdin:///' flags=[SENSITIVE]
 					"""
 				.replace("{{CWD}}", cwd);
 			assertEquals(expected, actual);