Only remove domain when FQDN is expected (#2286)

* Only remove domain when FQDN is expected

* ensure that host name is properly normalized

* add PR to changelog

Co-authored-by: Sylvain Juge <[email protected]>
Co-authored-by: jackshirazi <[email protected]>

Author: 3 people

CHANGELOG.asciidoc

@@ -26,6 +26,7 @@ endif::[]
 [float]
 ===== Bug fixes
 * Fixing missing Micrometer metrics in Spring boot due to premature initialization - {pull}2255[#2255]
+* Fixing hostname trimming of FQDN too aggressive - {pull}2286[#2286]
 
 [[release-notes-1.x]]
 === Java Agent version 1.x

apm-agent-core/src/main/java/co/elastic/apm/agent/impl/metadata/SystemInfo.java

@@ -139,8 +139,6 @@ static String discoverHostname(boolean isWindows, long timeoutMillis) {
         }
         if (hostname == null || hostname.isEmpty()) {
             logger.warn("Unable to discover hostname, set log_level to debug for more details");
-        } else {
-            hostname = removeDomain(hostname);
         }
         return hostname;
     }
@@ -151,6 +149,9 @@ static String fallbackHostnameDiscovery(boolean isWindows) {
         if (hostname == null || hostname.isEmpty()) {
             try {
                 hostname = InetAddress.getLocalHost().getHostName();
+                if (hostname != null) {
+                    hostname = removeDomain(hostname);
+                }
             } catch (Exception e) {
                 logger.warn("Last fallback for hostname discovery of localhost failed", e);
             }
@@ -194,7 +195,7 @@ private static String executeHostnameDiscoveryCommand(List<String> cmd, long tim
         String hostname = null;
         ProcessExecutionUtil.CommandOutput commandOutput = ProcessExecutionUtil.executeCommand(cmd, timeoutMillis);
         if (commandOutput.exitedNormally()) {
-            hostname = commandOutput.getOutput().toString();
+            hostname = commandOutput.getOutput().toString().trim();
             if (logger.isDebugEnabled()) {
                 logger.debug("hostname obtained by executing command {}: {}", cmdAsString(cmd), hostname);
             }

apm-agent-core/src/test/java/co/elastic/apm/agent/impl/metadata/SystemInfoTest.java

@@ -38,11 +38,13 @@ public class SystemInfoTest extends CustomEnvVariables {
         isWindows = SystemInfo.isWindows(systemInfo.getPlatform());
     }
 
-
     @Test
     void testHostnameDiscoveryThroughCommand() {
         String hostname = SystemInfo.discoverHostnameThroughCommand(isWindows, 300);
-        assertThat(hostname).isNotNull();
+        assertThat(hostname).isNotNull().isNotEmpty();
+        assertThat(hostname)
+            .describedAs("hostname command output should be normalized")
+            .isEqualTo(hostname.trim());
     }
 
     @Test
@@ -61,7 +63,7 @@ void testHostnameDiscoveryThroughEnv() {
 
     @Test
     void testHostnameDiscoveryFallbackThroughInetAddress() throws UnknownHostException {
-        String expectedHostname = InetAddress.getLocalHost().getHostName();
+        String expectedHostname = SystemInfo.removeDomain(InetAddress.getLocalHost().getHostName());
 
         Map<String, String> customEnvVariables = new HashMap<>();
         if (isWindows) {