Use the full Environment for module args

Rename to ModuleLaunchRequest

Add documentation for the format

Move request construction

Document launcher order

Fix empty args case

Update docs

spring-cloud-stream-module-launcher/README.md

@@ -23,10 +23,11 @@ From the `spring-cloud-stream/spring-cloud-stream-module-launcher` directory:
 
 ````
 java -Dmodules=org.springframework.cloud.stream.module:time-source:1.0.0.BUILD-SNAPSHOT -Dspring.cloud.stream.bindings.output=ticktock -jar target/spring-cloud-stream-module-launcher-1.0.0.BUILD-SNAPSHOT.jar
-java -Dmodules=org.springframework.cloud.stream.module:log-sink:1.0.0.BUILD-SNAPSHOT -Dserver.port=8081 -Dspring.cloud.stream.bindings.input=ticktock -jar target/spring-cloud-stream-module-launcher-1.0.0.BUILD-SNAPSHOT.jar
+java -Dmodules=org.springframework.cloud.stream.module:log-sink:1.0.0.BUILD-SNAPSHOT -Dargs.0.server.port=8081 -Dspring.cloud.stream.bindings.input=ticktock -jar target/spring-cloud-stream-module-launcher-1.0.0.BUILD-SNAPSHOT.jar
 ````
 
 Note that `server.port` needs to be specified explicitly for the log sink module as the time source module already uses the default port `8080`.
+The module launcher is able to launch several modules, hence the `args.0.` prefix.
 The binding property is set to use the same name `ticktock` for both the output/input bindings of source/sink modules so that the log sink receives messages from the time source.
 
 The time messages will be emitted every second. The console for the log module will display each:

spring-cloud-stream-module-launcher/src/main/java/org/springframework/cloud/stream/module/launcher/ModuleLaunchRequest.java

@@ -0,0 +1,57 @@
+/*
+ * Copyright 2015 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.cloud.stream.module.launcher;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import org.springframework.util.Assert;
+
+/**
+ * Encapsulates a reference to a module (as maven coordinates) and a set of "arguments" that must be passed to it.
+ * Those arguments will eventually be passed to the module by the launcher, using any way appropriate.
+ *
+ * @author Eric Bottard
+ */
+public class ModuleLaunchRequest {
+
+	private final String module;
+
+	private final Map<String, String> arguments;
+
+	public ModuleLaunchRequest(String module, Map<String, String> arguments) {
+		this.module = module;
+		this.arguments = arguments != null ? new HashMap<>(arguments) : new HashMap<String, String>();
+	}
+
+	public String getModule() {
+		return module;
+	}
+
+	public Map<String, String> getArguments() {
+		return arguments;
+	}
+
+	public void addArgument(String name, String value) {
+		this.arguments.put(name, value);
+	}
+
+	@Override
+	public String toString() {
+		return String.format("%s with arguments %s", module, arguments);
+	}
+}

spring-cloud-stream-module-launcher/src/main/java/org/springframework/cloud/stream/module/launcher/ModuleLauncher.java

@@ -18,7 +18,9 @@ package org.springframework.cloud.stream.module.launcher;
 
 import java.io.IOException;
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.List;
+import java.util.Map;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
@@ -36,6 +38,7 @@ import org.springframework.util.StringUtils;
  * @author Mark Fisher
  * @author Ilayaperumal Gopinathan
  * @author Marius Bogoevici
+ * @author Eric Bottard
  */
 public class ModuleLauncher {
 
@@ -59,28 +62,36 @@ public class ModuleLauncher {
 	/**
 	 * Launches one or more modules, with the corresponding arguments, if any.
 	 *
+	 * Modules must be passed in "natural" left to right order.
+	 *
 	 * The format of each module must conform to the <a href="http://www.eclipse.org/aether">Aether</a> convention:
 	 * <code>&lt;groupId&gt;:&lt;artifactId&gt;[:&lt;extension&gt;[:&lt;classifier&gt;]]:&lt;version&gt;</code>
 	 *
-	 * To pass arguments to a module, prefix with the module name and a dot. The arg name will be de-qualified and passed along.
-	 * For example: <code>--org.springframework.cloud.stream.module:time-source:1.0.0.BUILD-SNAPSHOT.bar=123</code> becomes <code>--bar=123</code> and is only passed to the 'org.springframework.cloud.stream.module:time-source:1.0.0.BUILD-SNAPSHOT' module.
-	 *
-	 * @param modules a list of modules
-	 * @param args a list of arguments, prefixed with the module name
+	 * @param moduleLaunchRequests a list of modules with their (unqualified) arguments
 	 */
-	public void launch(String[] modules, String[] args) {
-		for (String module : modules) {
-			List<String> moduleArgs = new ArrayList<>();
-			for (String arg : args) {
-				if (arg.startsWith("--" + module + ".")) {
-					moduleArgs.add("--" + arg.substring(module.length() + 3));
-				}
-			}
-			moduleArgs.add("--spring.jmx.default-domain=" + module.replace("/", ".").replace(":", "."));
-			launchModule(module, moduleArgs.toArray(new String[moduleArgs.size()]));
+	public void launch(List<ModuleLaunchRequest> moduleLaunchRequests) {
+		List<ModuleLaunchRequest> reversed = new ArrayList<>(moduleLaunchRequests);
+		Collections.reverse(reversed);
+		for (ModuleLaunchRequest moduleLaunchRequest : reversed) {
+			String module = moduleLaunchRequest.getModule();
+			moduleLaunchRequest.addArgument("spring.jmx.default-domain", module.replace("/", ".").replace(":", "."));
+			launchModule(module, toArgArray(moduleLaunchRequest.getArguments()));
 		}
 	}
 
+	/**
+	 * Converts a set of semantic program arguments to "command line program arguments" that is, to the
+	 * {@literal --foo=bar} form.
+	 */
+	private String[] toArgArray(Map<String, String> args) {
+		String[] result = new String[args.size()];
+		int i = 0;
+		for (Map.Entry<String, String> kv : args.entrySet()) {
+			result[i++] = String.format("--%s=%s", kv.getKey(), kv.getValue());
+		}
+		return result;
+	}
+
 	private void launchModule(String module, String[] args) {
 		try {
 			Resource resource = resolveModule(module);

spring-cloud-stream-module-launcher/src/main/java/org/springframework/cloud/stream/module/launcher/ModuleLauncherApplication.java

@@ -24,7 +24,7 @@ import org.springframework.boot.autoconfigure.SpringBootApplication;
  * or "MODULES" environment variable as a comma-delimited list, with the arguments
  * provided at launch.
  *
- * @see ModuleLauncher#launch(String[], String[]) for module and argument structure and
+ * @see ModuleLauncherProperties for module and argument structure and
  * format
  *
  * @author Marius Bogoevici

spring-cloud-stream-module-launcher/src/main/java/org/springframework/cloud/stream/module/launcher/ModuleLauncherConfiguration.java

@@ -33,6 +33,7 @@ import org.springframework.context.annotation.Configuration;
  *
  * @author Marius Bogoevici
  * @author Ilayaperumal Gopinathan
+ * @author Eric Bottard
  */
 @Configuration
 @EnableConfigurationProperties(ModuleResolverProperties.class)

spring-cloud-stream-module-launcher/src/main/java/org/springframework/cloud/stream/module/launcher/ModuleLauncherProperties.java

@@ -16,24 +16,50 @@
 
 package org.springframework.cloud.stream.module.launcher;
 
+import java.util.HashMap;
+import java.util.Map;
+
+import javax.validation.constraints.AssertFalse;
+
 import org.hibernate.validator.constraints.NotEmpty;
 
 import org.springframework.boot.context.properties.ConfigurationProperties;
+import org.springframework.core.env.Environment;
 
 /**
  * Configuration properties for {@link ModuleLauncher}.
  *
+ * <p>Expects the following keys (resolved from the {@link Environment}, so this could take many forms _ System
+ * properties, environment variables, program arguments, <i>etc.</i> _):<ul>
+ *     <li>{@literal modules = <list>}: an ordered list of maven coordinates of modules to launch</li>
+ *     <li>{@literal args[<index>][<key>] = <value>}: key/value pairs that will become module arguments,
+ *     where {@literal <index>} is the 0-based index of the module in the list above</li>
+ * </ul>
+ *
+ * As an example, this is how one would launch {@literal time --fixedDelay=4 | log} canonical example:
+ * <pre>
+ *     modules = org.springframework.cloud.modules:time-source:1.0.0-SNAPSHOT,org.springframework.cloud.modules:log-sink:1.0.0-SNAPSHOT
+ *     args.0.fixedDelay=4
+ * </pre>
+ * </p>
+ *
  * @author Ilayaperumal Gopinathan
  * @author Marius Bogoevici
+ * @author Eric Bottard
  */
 @ConfigurationProperties
 public class ModuleLauncherProperties {
 
 	/**
-	 * Array of modules that need to be launched.
+	 * Array of coordinates for modules that need to be launched.
 	 */
 	private String[] modules;
 
+	/**
+	 * Map of arguments, keyed by the 0-based index in the {@kink #modules array}.
+	 */
+	private Map<Integer, Map<String, String>> args = new HashMap<>();
+
 	public void setModules(String[] modules) {
 		this.modules = modules;
 	}
@@ -43,4 +69,12 @@ public class ModuleLauncherProperties {
 		return modules;
 	}
 
+	public void setArgs(Map<Integer, Map<String, String>> args) {
+		this.args = args;
+	}
+
+	public Map<Integer, Map<String, String>> getArgs() {
+		return args;
+	}
+
 }

spring-cloud-stream-module-launcher/src/main/java/org/springframework/cloud/stream/module/launcher/ModuleLauncherRunner.java

@@ -16,15 +16,18 @@
 
 package org.springframework.cloud.stream.module.launcher;
 
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 
 import org.springframework.beans.factory.annotation.Autowired;
-import org.springframework.boot.ApplicationArguments;
 import org.springframework.boot.ApplicationRunner;
+import org.springframework.boot.CommandLineRunner;
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
 import org.springframework.stereotype.Component;
-import org.springframework.util.StringUtils;
 
 /**
  * Spring boot {@link ApplicationRunner} that triggers {@link ModuleLauncher} to launch the modules.
@@ -34,7 +37,7 @@ import org.springframework.util.StringUtils;
  */
 @Component
 @EnableConfigurationProperties(ModuleLauncherProperties.class)
-public class ModuleLauncherRunner implements ApplicationRunner {
+public class ModuleLauncherRunner implements CommandLineRunner {
 
 	private final static Log log = LogFactory.getLog(ModuleLauncherRunner.class);
 
@@ -45,15 +48,27 @@ public class ModuleLauncherRunner implements ApplicationRunner {
 	private ModuleLauncher moduleLauncher;
 
 	@Override
-	public void run(ApplicationArguments applicationArguments) throws Exception {
-		String[] launchedModules = moduleLauncherProperties.getModules();
+	public void run(String... args) throws Exception {
+		List<ModuleLaunchRequest> launchRequests = toModuleLaunchRequests(moduleLauncherProperties);
 		if (log.isInfoEnabled()) {
-			log.info("Launching: "
-					+ StringUtils.arrayToCommaDelimitedString(launchedModules)
-					+ " with arguments: "
-					+ StringUtils.arrayToCommaDelimitedString(applicationArguments
-							.getSourceArgs()));
+			StringBuilder sb = new StringBuilder("Launching\n");
+			for (ModuleLaunchRequest moduleLaunchRequest : launchRequests) {
+				sb.append('\t').append(moduleLaunchRequest).append('\n');
+			}
+			log.info(sb.toString());
 		}
-		this.moduleLauncher.launch(launchedModules, applicationArguments.getSourceArgs());
+		this.moduleLauncher.launch(launchRequests);
+	}
+
+	private List<ModuleLaunchRequest> toModuleLaunchRequests(ModuleLauncherProperties moduleLauncherProperties) {
+		List<ModuleLaunchRequest> requests = new ArrayList<>();
+		String[] modules = moduleLauncherProperties.getModules();
+		Map<Integer, Map<String, String>> arguments = moduleLauncherProperties.getArgs();
+		for (int i = 0; i < modules.length; i++) {
+			ModuleLaunchRequest moduleLaunchRequest = new ModuleLaunchRequest(modules[i], arguments.get(i));
+			requests.add(moduleLaunchRequest);
+		}
+		return requests;
+
 	}
 }