[MONIT-32096] Better Local Hostname detection (#817)

Author: laullon

proxy/src/main/java/com/wavefront/agent/AbstractAgent.java

@@ -202,7 +202,7 @@ private void postProcessConfig() {
     //     setLevel(org.apache.log4j.Level.WARN);
     // Logger.getLogger("org.apache.http.impl.execchain.RetryExec").setLevel(Level.WARNING);
 
-    if (StringUtils.isBlank(proxyConfig.getHostname().trim())) {
+    if (StringUtils.isBlank(proxyConfig.getHostname())) {
       throw new IllegalArgumentException(
           "hostname cannot be blank! Please correct your configuration settings.");
     }
@@ -223,24 +223,14 @@ private void postProcessConfig() {
   @VisibleForTesting
   void parseArguments(String[] args) {
     // read build information and print version.
-    String versionStr =
-        "Wavefront Proxy version "
-            + getBuildVersion()
-            + " (pkg:"
-            + getPackage()
-            + ")"
-            + ", runtime: "
-            + getJavaVersion();
     try {
       if (!proxyConfig.parseArguments(args, this.getClass().getCanonicalName())) {
         System.exit(0);
       }
     } catch (ParameterException e) {
-      logger.info(versionStr);
       logger.severe("Parameter exception: " + e.getMessage());
       System.exit(1);
     }
-    logger.info(versionStr);
     logger.info(
         "Arguments: "
             + IntStream.range(0, args.length)

proxy/src/main/java/com/wavefront/agent/ProxyConfig.java

@@ -795,13 +795,13 @@ public class ProxyConfig extends Configuration {
   @Parameter(
       names = {"--hostname"},
       description = "Hostname for the proxy. Defaults to FQDN of machine.")
-  String hostname = getLocalHostName();
+  String hostname = null;
 
   /** This property holds the proxy name. Default proxyname to FQDN of machine. */
   @Parameter(
       names = {"--proxyname"},
       description = "Name for the proxy. Defaults to hostname.")
-  String proxyname = getLocalHostName();
+  String proxyname = null;
 
   @Parameter(
       names = {"--idFile"},
@@ -2287,15 +2287,21 @@ public void verifyAndInit() {
       token = ObjectUtils.firstNonNull(config.getRawProperty("token", token), "undefined").trim();
       server = config.getString("server", server);
 
-      String FQDN = getLocalHostName();
-      hostname = config.getString("hostname", hostname);
-      proxyname = config.getString("proxyname", proxyname);
-      if (!hostname.equals(FQDN)) {
+      String _hostname = config.getString("hostname", hostname);
+      if (!Strings.isNullOrEmpty(_hostname)) {
         logger.warning(
             "Deprecated field hostname specified in config setting. Please use "
                 + "proxyname config field to set proxy name.");
-        if (proxyname.equals(FQDN)) proxyname = hostname;
+        hostname = _hostname;
+      } else {
+        hostname = getLocalHostName();
+      }
+
+      proxyname = config.getString("proxyname", proxyname);
+      if (Strings.isNullOrEmpty(proxyname)) {
+        proxyname = hostname;
       }
+
       logger.info("Using proxyname:'" + proxyname + "' hostname:'" + hostname + "'");
 
       idFile = config.getString("idFile", idFile);
@@ -2803,7 +2809,6 @@ limited system resources (4 CPU cores or less, heap size less than 4GB) to preve
    * @throws ParameterException if configuration parsing failed
    */
   public boolean parseArguments(String[] args, String programName) throws ParameterException {
-    String versionStr = "Wavefront Proxy version " + getBuildVersion();
     JCommander jCommander =
         JCommander.newBuilder()
             .programName(programName)
@@ -2812,11 +2817,9 @@ public boolean parseArguments(String[] args, String programName) throws Paramete
             .build();
     jCommander.parse(args);
     if (this.isVersion()) {
-      System.out.println(versionStr);
       return false;
     }
     if (this.isHelp()) {
-      System.out.println(versionStr);
       jCommander.usage();
       return false;
     }

proxy/src/main/java/com/wavefront/agent/PushAgent.java

@@ -6,8 +6,7 @@
 import static com.wavefront.agent.data.EntityProperties.NO_RATE_LIMIT;
 import static com.wavefront.agent.handlers.ReportableEntityHandlerFactoryImpl.VALID_HISTOGRAMS_LOGGER;
 import static com.wavefront.agent.handlers.ReportableEntityHandlerFactoryImpl.VALID_POINTS_LOGGER;
-import static com.wavefront.common.Utils.csvToList;
-import static com.wavefront.common.Utils.lazySupplier;
+import static com.wavefront.common.Utils.*;
 
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Preconditions;
@@ -209,6 +208,15 @@ public class PushAgent extends AbstractAgent {
 
   public static void main(String[] args) {
     // Start the ssh daemon
+    String versionStr =
+        "Wavefront Proxy version "
+            + getBuildVersion()
+            + " (pkg:"
+            + getPackage()
+            + ")"
+            + ", runtime: "
+            + getJavaVersion();
+    logger.info(versionStr);
     new PushAgent().start(args);
   }
 

proxy/src/main/java/com/wavefront/common/Utils.java

@@ -5,16 +5,16 @@
 import com.fasterxml.jackson.databind.ObjectMapper;
 import com.google.common.base.Splitter;
 import com.google.common.collect.ImmutableList;
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
 import java.net.Inet4Address;
 import java.net.InetAddress;
 import java.net.NetworkInterface;
 import java.net.SocketException;
-import java.util.Collections;
-import java.util.Enumeration;
-import java.util.List;
-import java.util.MissingResourceException;
-import java.util.ResourceBundle;
+import java.util.*;
 import java.util.function.Supplier;
+import java.util.logging.Logger;
 import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
 import javax.ws.rs.core.Response;
@@ -31,6 +31,8 @@ public abstract class Utils {
   private static final ResourceBundle buildProps = ResourceBundle.getBundle("build");
   private static final List<Integer> UUID_SEGMENTS = ImmutableList.of(8, 4, 4, 4, 12);
 
+  private static final Logger log = Logger.getLogger(Utils.class.getCanonicalName());
+
   /**
    * A lazy initialization wrapper for {@code Supplier}
    *
@@ -155,6 +157,27 @@ public static String getJavaVersion() {
    * @return name for localhost
    */
   public static String getLocalHostName() {
+    for (String env : Arrays.asList("COMPUTERNAME", "HOSTNAME", "PROXY_HOSTNAME")) {
+      String hostname = System.getenv(env);
+      if (StringUtils.isNotBlank(hostname)) {
+        log.info("Hostname: '" + hostname + "' (detected using '" + env + "' env variable)");
+        return hostname;
+      }
+    }
+
+    try {
+      String hostname =
+          new BufferedReader(
+                  new InputStreamReader(Runtime.getRuntime().exec("hostname").getInputStream()))
+              .readLine();
+      if (StringUtils.isNotBlank(hostname)) {
+        log.info("Hostname: '" + hostname + "' (detected using 'hostname' command)");
+        return hostname;
+      }
+    } catch (IOException e) {
+      log.fine("Error running 'hostname' command. " + e.getMessage());
+    }
+
     InetAddress localAddress = null;
     try {
       Enumeration<NetworkInterface> nics = NetworkInterface.getNetworkInterfaces();
@@ -184,8 +207,12 @@ public static String getLocalHostName() {
       // ignore
     }
     if (localAddress != null) {
-      return localAddress.getCanonicalHostName();
+      String hostname = localAddress.getCanonicalHostName();
+      log.info("Hostname: '" + hostname + "' (detected using network interfaces)");
+      return hostname;
     }
+
+    log.info("Hostname not detected, using 'localhost')");
     return "localhost";
   }