Capture FQDN for host name

CHANGELOG.asciidoc

@@ -37,6 +37,7 @@ Use subheadings with the "=====" level for adding notes for unreleased changes:
 * Prevent overriding `ELASTIC_APM_AWS_LAMBDA_HANDLER` in AWS lambda execution when explicitly set - {pull}3205[#3205]
 * Ignore gc allocation metrics when unsupported - {pull}3225[#3225]
 * Avoid warning log message when grpc transactions are cancelled before end - {pull}3223[#3223]
+* Align agent hostname capture to FQDN - {pull}3188[#3188]
 
 [[release-notes-1.x]]
 === Java Agent version 1.x

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

@@ -31,7 +31,9 @@
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.List;
+import java.util.Locale;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
@@ -156,9 +158,6 @@ 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);
             }
@@ -169,23 +168,13 @@ static String fallbackHostnameDiscovery(boolean isWindows) {
     @Nullable
     static String discoverHostnameThroughCommand(boolean isWindows, long timeoutMillis) {
         String hostname;
-        List<String> cmd;
         if (isWindows) {
-            cmd = new ArrayList<>();
-            cmd.add("cmd");
-            cmd.add("/c");
-            cmd.add("hostname");
-            hostname = executeHostnameDiscoveryCommand(cmd, timeoutMillis);
-        } else {
-            cmd = new ArrayList<>();
-            cmd.add("uname");
-            cmd.add("-n");
-            hostname = executeHostnameDiscoveryCommand(cmd, timeoutMillis);
+            hostname = executeHostnameDiscoveryCommand(Arrays.asList("powershell.exe", "[System.Net.Dns]::GetHostEntry($env:computerName).HostName"), timeoutMillis);
             if (hostname == null || hostname.isEmpty()) {
-                cmd = new ArrayList<>();
-                cmd.add("hostname");
-                hostname = executeHostnameDiscoveryCommand(cmd, timeoutMillis);
+                hostname = executeHostnameDiscoveryCommand(Arrays.asList("cmd.exe", "/c", "hostname"), timeoutMillis);
             }
+        } else {
+            hostname = executeHostnameDiscoveryCommand(Arrays.asList("hostname", "-f"), timeoutMillis);
         }
         return hostname;
     }
@@ -210,6 +199,9 @@ private static String executeHostnameDiscoveryCommand(List<String> cmd, long tim
             logger.info("Failed to execute command {} with exit code {}", cmdAsString(cmd), commandOutput.getExitCode());
             logger.debug("Command execution error", commandOutput.getExceptionThrown());
         }
+        if(hostname != null) {
+            hostname = hostname.toLowerCase(Locale.ROOT);
+        }
         return hostname;
     }
 
@@ -236,13 +228,8 @@ static String discoverHostnameThroughEnv(boolean isWindows) {
                 hostname = System.getenv("HOST");
             }
         }
-        return hostname;
-    }
-
-    static String removeDomain(String hostname) {
-        int indexOfDot = hostname.indexOf('.');
-        if (indexOfDot > 0) {
-            hostname = hostname.substring(0, indexOfDot);
+        if (hostname != null) {
+            hostname = hostname.toLowerCase(Locale.ROOT);
         }
         return hostname;
     }

apm-agent-core/src/main/java/co/elastic/apm/agent/report/serialize/DslJsonSerializer.java

@@ -134,14 +134,20 @@ private void waitForMetadata() throws Exception {
             serializedActivationMethod = supportsActivationMethod;
 
             JsonWriter metadataJW = new DslJson<>(new DslJson.Settings<>()).newWriter(4096);
-            boolean supportsConfiguredAndDetectedHostname = apmServerClient.supportsConfiguredAndDetectedHostname();
 
-            serializeMetadata(meta, metadataJW, supportsConfiguredAndDetectedHostname, supportsActivationMethod);
+            serializeMetadata(meta, metadataJW,
+                apmServerClient.supportsConfiguredAndDetectedHostname(),
+                supportsActivationMethod);
+
             serializedMetaData = metadataJW.toByteArray();
         }
     }
 
-    static void serializeMetadata(MetaData metaData, JsonWriter metadataJW, boolean supportsConfiguredAndDetectedHostname, boolean supportsAgentActivationMethod) {
+    static void serializeMetadata(MetaData metaData,
+                                  JsonWriter metadataJW,
+                                  boolean supportsConfiguredAndDetectedHostname,
+                                  boolean supportsAgentActivationMethod) {
+
         StringBuilder metadataReplaceBuilder = new StringBuilder();
         metadataJW.writeByte(JsonWriter.OBJECT_START);
         serializeService(metaData.getService(), metadataReplaceBuilder, metadataJW, supportsAgentActivationMethod);
@@ -327,8 +333,11 @@ private static void serializeProcess(final ProcessInfo process, final StringBuil
         jw.writeByte(JsonWriter.OBJECT_END);
     }
 
-    private static void serializeSystem(final SystemInfo system, final StringBuilder replaceBuilder, final JsonWriter jw,
+    private static void serializeSystem(SystemInfo system,
+                                        StringBuilder replaceBuilder,
+                                        JsonWriter jw,
                                         boolean supportsConfiguredAndDetectedHostname) {
+
         writeFieldName("system", jw);
         jw.writeByte(JsonWriter.OBJECT_START);
         serializeContainerInfo(system.getContainerInfo(), replaceBuilder, jw);

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

@@ -59,18 +59,18 @@ void testHostnameDiscoveryThroughEnv() {
             // when running on Windows the actual computer name will be the netbios name, thus won't match exactly
             // the entry in the map. It's fine here for testing as it just proves we get the expected value set in map
             customEnvVariables.put("COMPUTERNAME", "Windows_hostname");
-            runWithCustomEnvVariables(customEnvVariables, () -> assertThat(SystemInfo.discoverHostnameThroughEnv(true)).isEqualTo("Windows_hostname"));
+            runWithCustomEnvVariables(customEnvVariables, () -> assertThat(SystemInfo.discoverHostnameThroughEnv(true)).isEqualTo("windows_hostname"));
         } else {
             customEnvVariables.put("HOST", "macOS_hostname");
-            runWithCustomEnvVariables(customEnvVariables, () -> assertThat(SystemInfo.discoverHostnameThroughEnv(false)).isEqualTo("macOS_hostname"));
+            runWithCustomEnvVariables(customEnvVariables, () -> assertThat(SystemInfo.discoverHostnameThroughEnv(false)).isEqualTo("macos_hostname"));
             customEnvVariables.put("HOSTNAME", "Linux_hostname");
-            runWithCustomEnvVariables(customEnvVariables, () -> assertThat(SystemInfo.discoverHostnameThroughEnv(false)).isEqualTo("Linux_hostname"));
+            runWithCustomEnvVariables(customEnvVariables, () -> assertThat(SystemInfo.discoverHostnameThroughEnv(false)).isEqualTo("linux_hostname"));
         }
     }
 
     @Test
     void testHostnameDiscoveryFallbackThroughInetAddress() throws UnknownHostException {
-        String expectedHostname = SystemInfo.removeDomain(InetAddress.getLocalHost().getHostName());
+        String expectedHostname = InetAddress.getLocalHost().getHostName();
 
         Map<String, String> customEnvVariables = new HashMap<>();
         // none of those env variables should be available to trigger the fallback on all platforms
@@ -81,27 +81,21 @@ void testHostnameDiscoveryFallbackThroughInetAddress() throws UnknownHostExcepti
         runWithCustomEnvVariables(customEnvVariables, () -> {
 
             // sanity check for test instrumentation to ensure those are not set
-            checkSystemPropertiesNotSet("HOST","HOSTNAME","COMPUTERNAME");
+            checkSystemPropertiesNotSet("HOST", "HOSTNAME", "COMPUTERNAME");
 
             assertThat(SystemInfo.fallbackHostnameDiscovery(isWindows))
                 .isEqualTo(expectedHostname);
         });
     }
 
-    private static void checkSystemPropertiesNotSet(String... keys){
+    private static void checkSystemPropertiesNotSet(String... keys) {
         Map<String, String> map = System.getenv();
         for (String key : keys) {
             assertThat(System.getenv(key)).isNull();
             assertThat(map.get(key)).isNull();
         }
     }
 
-    @Test
-    void testDomainRemoval() {
-        assertThat(SystemInfo.removeDomain("hostname")).isEqualTo("hostname");
-        assertThat(SystemInfo.removeDomain("hostname.and.domain")).isEqualTo("hostname");
-    }
-
     @Test
     void testLambdaShortcut() {
         doReturn(true).when(serverlessConfiguration).runsOnAwsLambda();

apm-agent-core/src/test/java/co/elastic/apm/agent/report/serialize/DslJsonSerializerTest.java

@@ -1088,12 +1088,12 @@ void testSystemInfo_configuredHostname(boolean supportsConfiguredAndDetectedHost
     }
 
     @ParameterizedTest
-    @ValueSource(booleans = {true, false})
+    @ValueSource(booleans = {false,true})
     void testSystemInfo_detectedHostname(boolean supportsConfiguredAndDetectedHostname) throws Exception {
         String arc = "test-arc";
         String platform = "test-platform";
 
-        MetaData metaData = createMetaData(new SystemInfo(arc, null, "detected", platform));
+        MetaData metaData = createMetaData(new SystemInfo(arc, null, "detected.fqdn", platform));
         DslJsonSerializer.serializeMetadata(metaData, writer.getJsonWriter(), supportsConfiguredAndDetectedHostname, true);
         writer.appendMetadataToStream();
 
@@ -1103,12 +1103,12 @@ void testSystemInfo_detectedHostname(boolean supportsConfiguredAndDetectedHostna
         assertThat(platform).isEqualTo(system.get("platform").asText());
         if (supportsConfiguredAndDetectedHostname) {
             assertThat(system.get("configured_hostname")).isNull();
-            assertThat(system.get("detected_hostname").asText()).isEqualTo("detected");
+            assertThat(system.get("detected_hostname").asText()).isEqualTo("detected.fqdn");
             assertThat(system.get("hostname")).isNull();
         } else {
             assertThat(system.get("configured_hostname")).isNull();
             assertThat(system.get("detected_hostname")).isNull();
-            assertThat(system.get("hostname").asText()).isEqualTo("detected");
+            assertThat(system.get("hostname").asText()).isEqualTo("detected.fqdn");
         }
     }