Store and print revision info from manifest file.

build.gradle

@@ -21,13 +21,31 @@ distZip {
 }
 tasks.distTar.enabled = false
 
+// Return the current commit hash from git
+def scmRevisionInfo() {
+  new ByteArrayOutputStream().withStream { os ->
+    def result = exec {
+      executable = 'git'
+      args = [ 'rev-parse', 'HEAD' ]
+      standardOutput = os
+    }
+    return os.toString().trim()
+  }
+}
+
+def utcDateTime() {
+  def df = new java.text.SimpleDateFormat("yyyy-MM-dd HH:mm 'UTC'");
+  df.setTimeZone(TimeZone.getTimeZone("UTC"));
+  return df.format(new Date())
+}
+
 jar {
   manifest {
     attributes 'Implementation-Title'  : project.description,
                'Implementation-Version': version,
                'Built-By'              : System.properties['user.name'],
-               'Build-Date'            : new java.text.SimpleDateFormat("yyyy-MM-dd").format(new Date()),
-               'Build-Revision'        : "TODO",
+               'Build-Date'            : utcDateTime(),
+               'Build-Revision'        : scmRevisionInfo(),
                'Created-By'            : "Gradle ${gradle.gradleVersion}",
                'Build-Jdk'             : "${System.properties['java.version']} (${System.properties['java.vendor']} ${System.properties['java.vm.version']})",
                'Build-OS'              : "${System.properties['os.name']} ${System.properties['os.arch']} ${System.properties['os.version']}"

src/main/java/com/mecatran/gtfsvtor/cmdline/GtfsVtorMain.java

@@ -1,5 +1,8 @@
 package com.mecatran.gtfsvtor.cmdline;
 
+import java.util.Calendar;
+import java.util.GregorianCalendar;
+
 import com.beust.jcommander.JCommander;
 import com.mecatran.gtfsvtor.lib.GtfsVtor;
 import com.mecatran.gtfsvtor.reporting.ReportIssueSeverity;
@@ -8,14 +11,16 @@
 
 public class GtfsVtorMain {
 
-	// TODO This is a minimal dummy example
 	public static void main(String[] args) throws Exception {
 
-		System.out.println("GTFSVTOR, development version\n"
-				+ "Copyright (c) 2020 Mecatran\n"
+		Calendar cal = GregorianCalendar.getInstance();
+		ManifestReader mfr = new ManifestReader(GtfsVtorMain.class);
+		System.out.println(String.format("GTFSVTOR version %s\n"
+				+ "Copyright (c) %d Mecatran\n"
 				+ "This program comes with absolutely no warranty.\n"
 				+ "This is free software, and you are welcome to redistribute it\n"
-				+ "under certain conditions; see the license file for details.\n");
+				+ "under certain conditions; see the license file for details.\n",
+				mfr.getApplicationVersion(), cal.get(Calendar.YEAR)));
 
 		CmdLineArgs cmdLineArgs = new CmdLineArgs();
 		JCommander jcmd = JCommander.newBuilder().addObject(cmdLineArgs)
@@ -39,6 +44,10 @@ public static void main(String[] args) throws Exception {
 
 		if (cmdLineArgs.isHelp() || cmdLineArgs.getGtfsFile() == null) {
 			jcmd.usage();
+			System.out.println(String.format(
+					"Version %s build at %s from commit %s",
+					mfr.getApplicationVersion(), mfr.getApplicationBuildDate(),
+					mfr.getApplicationBuildRevision()));
 			System.exit(1);
 		}
 

src/main/java/com/mecatran/gtfsvtor/cmdline/ManifestReader.java

@@ -0,0 +1,56 @@
+package com.mecatran.gtfsvtor.cmdline;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.net.URL;
+import java.util.jar.Attributes;
+import java.util.jar.Manifest;
+
+public class ManifestReader {
+
+	public static String IMPL_VERSION = "Implementation-Version";
+	public static String BUILD_REV = "Build-Revision";
+	public static String BUILD_DATE = "Build-Date";
+
+	private Attributes attr;
+
+	public ManifestReader(Class<?> clazz) {
+		String className = clazz.getSimpleName() + ".class";
+		String classPath = clazz.getResource(className).toString();
+		if (!classPath.startsWith("jar")) {
+			return;
+		}
+		String manifestPath = classPath.substring(0,
+				classPath.lastIndexOf("!") + 1) + "/META-INF/MANIFEST.MF";
+		try {
+			URL url = new URL(manifestPath);
+			InputStream input = url.openStream();
+			Manifest manifest = new Manifest(input);
+			input.close();
+			attr = manifest.getMainAttributes();
+		} catch (IOException e) {
+			System.err.println("Cannot read manifest: " + e);
+		}
+	}
+
+	public String getValue(String attrName, String def) {
+		if (attr == null)
+			return def;
+		String value = attr.getValue(attrName);
+		if (value == null)
+			return def;
+		return value;
+	}
+
+	public String getApplicationVersion() {
+		return getValue(IMPL_VERSION, "dev");
+	}
+
+	public String getApplicationBuildRevision() {
+		return getValue(BUILD_REV, "dev");
+	}
+
+	public String getApplicationBuildDate() {
+		return getValue(BUILD_DATE, "now");
+	}
+}