Issue #433: Disable automatic Hostname to FQDN resolution

* Now the engine resolves FQDN based on `resolveHostnameToFqdn`.
* `resolveHostnameToFqdn` is set to false by default.
* Simplified Host Resource creation in the agent.
* Added `--resolve-fqdn` option to the CLI.
* The Resource is now reported by the CLI.

metricshub-agent/src/main/java/org/sentrysoftware/metricshub/agent/config/AgentConfig.java

@@ -94,8 +94,7 @@ public class AgentConfig {
 
 	private boolean sequential;
 
-	@Default
-	private boolean resolveHostnameToFqdn = true;
+	private boolean resolveHostnameToFqdn;
 
 	@Default
 	@JsonSetter(nulls = SKIP)

metricshub-agent/src/main/java/org/sentrysoftware/metricshub/agent/helper/ConfigHelper.java

@@ -1047,6 +1047,7 @@ static HostConfiguration buildHostConfiguration(
 			.sequential(Boolean.TRUE.equals(resourceConfig.getSequential()))
 			.configuredConnectorId(configuredConnectorId)
 			.connectorVariables(resourceConfig.getVariables())
+			.resolveHostnameToFqdn(resourceConfig.getResolveHostnameToFqdn())
 			.build();
 	}
 

metricshub-agent/src/main/java/org/sentrysoftware/metricshub/agent/helper/OtelHelper.java

@@ -21,8 +21,6 @@
  * ╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱
  */
 
-import static org.sentrysoftware.metricshub.engine.common.helpers.MetricsHubConstants.HOST_NAME;
-
 import io.opentelemetry.api.common.AttributeKey;
 import io.opentelemetry.api.common.Attributes;
 import io.opentelemetry.sdk.autoconfigure.AutoConfiguredOpenTelemetrySdk;
@@ -40,11 +38,6 @@
 @NoArgsConstructor(access = AccessLevel.PRIVATE)
 public class OtelHelper {
 
-	/**
-	 * Fully Qualified Domain Name (FQDN) attribute key
-	 */
-	public static final String FQDN_ATTRIBUTE_KEY = "fqdn";
-
 	/**
 	 * Create an OTEL Resource
 	 *
@@ -106,75 +99,36 @@ public static AutoConfiguredOpenTelemetrySdk initOpenTelemetrySdk(
 	}
 
 	/**
-	 * Create the host resource based on the given attributes
+	 * Create the host resource based on the given attributes.
 	 *
-	 * @param hostAttributes        Host attributes: host.id, host.name, os.type, host.type, etc
-	 *                              collected by the engine
-	 * @param userAttributes        User configured attributes
-	 * @param resolveHostnameToFqdn Whether we must resolve the hostname of the host to a
-	 *                              Fully Qualified Domain Name (FQDN)
-	 * @return OTEL {@link Resource} instance
+	 * @param computedHostResourceAttributes Host Resource attributes: host.id, host.name, os.type, host.type, etc
+	 *                                       collected by the engine.
+	 * @param userAttributes                 User configured attributes.
+	 * @return OTEL {@link Resource} instance representing the host.
 	 */
 	public static Resource createHostResource(
-		@NonNull final Map<String, String> hostAttributes,
-		@NonNull final Map<String, String> userAttributes,
-		final boolean resolveHostnameToFqdn
+		@NonNull final Map<String, String> computedHostResourceAttributes,
+		@NonNull final Map<String, String> userAttributes
 	) {
-		// Get the resource host.name attribute value
-		final String hostname = resolveResourceHostname(
-			hostAttributes.get(HOST_NAME),
-			userAttributes.get(HOST_NAME),
-			resolveHostnameToFqdn,
-			userAttributes.get(FQDN_ATTRIBUTE_KEY)
-		);
-
 		// Prepare the resource attributes
-		final Map<String, String> attributes = new HashMap<>();
-		attributes.putAll(hostAttributes);
-		attributes.put(HOST_NAME, hostname);
+		final Map<String, String> attributes = new HashMap<>(computedHostResourceAttributes);
 
-		// Add user attributes
-		userAttributes.entrySet().stream().forEach(entry -> attributes.putIfAbsent(entry.getKey(), entry.getValue()));
+		// Add user attributes to the resource attributes
+		// host.name is managed by the engine based on the resolveHostnameToFqdn flag, so we shouldn't override it here.
+		// host.type is managed by the engine using a set of rules to determine the host.type in OTEL format so we shouldn't override it here.
+		// The other attributes are user-defined so we can override them.
+		userAttributes
+			.entrySet()
+			.stream()
+			.filter(keyValue -> {
+				final String key = keyValue.getKey();
+				return !key.equals("host.name") && !key.equals("host.type");
+			})
+			.forEach(entry -> attributes.put(entry.getKey(), entry.getValue()));
 
 		return createOpenTelemetryResource(attributes);
 	}
 
-	/**
-	 * Resolve the resource hostname.
-	 *
-	 * Priority
-	 * <ol>
-	 *   <li>User's attribute <code>fqdn</code> with <code>resolveHostnameToFqdn=true</code></li>
-	 *   <li>Collected <code>fqdn</code> when the <code>resolveHostnameToFqdn=true</code></li>
-	 *   <li>Configured host name attribute <code>host.name</code></li>
-	 * </ol>
-	 *
-	 * @param collectedFqdn         Collected fqdn
-	 * @param configuredHostname    Configured host's host.name
-	 * @param resolveHostnameToFqdn Whether we must resolve host.name value to a fully qualified domain name.
-	 * @param userFqdn              FQDN attribute value
-	 * @return String value
-	 */
-	public static String resolveResourceHostname(
-		final String collectedFqdn,
-		final String configuredHostname,
-		final boolean resolveHostnameToFqdn,
-		final String userFqdn
-	) {
-		if (resolveHostnameToFqdn) {
-			// User's Fqdn?
-			if (userFqdn != null) {
-				return userFqdn;
-			} else {
-				// Collected Fqdn
-				return collectedFqdn;
-			}
-		}
-
-		// Finally we keep the configured host.name
-		return configuredHostname;
-	}
-
 	/**
 	 * Merge the given OTEL SDK attributes
 	 *

metricshub-agent/src/main/java/org/sentrysoftware/metricshub/agent/service/task/MonitoringTask.java

@@ -386,11 +386,7 @@ void initOtelSdk(final TelemetryManager telemetryManager, final ResourceConfig r
 				hostMonitorResourceAttributes = Map.of();
 			}
 
-			final Resource resource = OtelHelper.createHostResource(
-				hostMonitorResourceAttributes,
-				userAttributes,
-				resourceConfig.getResolveHostnameToFqdn()
-			);
+			final Resource resource = OtelHelper.createHostResource(hostMonitorResourceAttributes, userAttributes);
 
 			// Store the host monitor attributes for future use
 			mainResourceAttributes =

metricshub-agent/src/main/java/org/sentrysoftware/metricshub/cli/service/MetricsHubCliService.java

@@ -179,9 +179,6 @@ public class MetricsHubCliService implements Callable<Integer> {
 	)
 	char[] password;
 
-	@Option(names = { "-pd", "--patch-directory" }, order = 5, description = "Patch path to the connectors directory")
-	String patchDirectory;
-
 	@Option(
 		names = { "-c", "--connectors" },
 		order = 4,
@@ -197,6 +194,9 @@ public class MetricsHubCliService implements Callable<Integer> {
 	)
 	Set<String> connectors;
 
+	@Option(names = { "-pd", "--patch-directory" }, order = 5, description = "Patch path to the connectors directory")
+	String patchDirectory;
+
 	@Option(
 		names = { "-s", "--sequential" },
 		order = 6,
@@ -212,15 +212,15 @@ public class MetricsHubCliService implements Callable<Integer> {
 	@Option(
 		names = { "-l", "--list" },
 		help = true,
-		order = 7,
+		order = 8,
 		description = "Lists all connectors bundled in the engine that can be selected or excluded"
 	)
 	boolean listConnectors;
 
 	@Option(
 		names = { "-i", "--iterations" },
 		help = true,
-		order = 8,
+		order = 9,
 		defaultValue = "1",
 		description = "Executes the collect strategies N times, where N is the number of iterations"
 	)
@@ -229,21 +229,30 @@ public class MetricsHubCliService implements Callable<Integer> {
 	@Option(
 		names = { "-si", "--sleep-iteration" },
 		help = true,
-		order = 9,
+		order = 10,
 		defaultValue = "5",
 		description = "Adds a sleep period in seconds between collect iterations"
 	)
 	long sleepIteration;
 
 	@Option(
 		names = { "-m", "--monitors" },
-		order = 10,
+		order = 11,
 		paramLabel = "MONITOR",
 		split = ",",
 		description = "Comma-separated list of monitor types to filter. %nExamples: +disk,+file_system,!memory"
 	)
 	Set<String> monitorTypes;
 
+	@Option(
+		names = { "-r", "--resolve-fqdn" },
+		order = 12,
+		defaultValue = "false",
+		description = "Resolves the provided HOSTNAME to its Fully Qualified Domain Name (FQDN)",
+		help = true
+	)
+	boolean resolveHostnameToFqdn;
+
 	@Override
 	public Integer call() throws Exception {
 		// Check whether iterations is greater than 0. If it's not the case, throw a ParameterException
@@ -269,6 +278,7 @@ public Integer call() throws Exception {
 			.hostname(hostname)
 			.hostType(deviceType)
 			.sequential(sequential)
+			.resolveHostnameToFqdn(resolveHostnameToFqdn)
 			.build();
 
 		// Connectors

metricshub-agent/src/main/java/org/sentrysoftware/metricshub/cli/service/PrettyPrinterService.java

@@ -53,6 +53,7 @@
 import org.sentrysoftware.metricshub.engine.connector.model.metric.MetricDefinition;
 import org.sentrysoftware.metricshub.engine.telemetry.MetricFactory;
 import org.sentrysoftware.metricshub.engine.telemetry.Monitor;
+import org.sentrysoftware.metricshub.engine.telemetry.Resource;
 import org.sentrysoftware.metricshub.engine.telemetry.TelemetryManager;
 import org.sentrysoftware.metricshub.engine.telemetry.metric.AbstractMetric;
 import org.sentrysoftware.metricshub.engine.telemetry.metric.NumberMetric;
@@ -69,6 +70,15 @@
 @Data
 public class PrettyPrinterService {
 
+	/**
+	 * The header for the resource section
+	 */
+	static final String RESOURCE_HEADER = "Resource:";
+	/**
+	 * The header for the attributes section
+	 */
+	static final String ATTRIBUTES_HEADER = "Attributes:";
+
 	// @formatter:off
 	/**
 	 * Defines the priority order for different monitor types
@@ -162,7 +172,13 @@ private void print(final MonitorChildren monitorChildren, final int indentation)
 		printWriter.println(Ansi.ansi().fgCyan().a(getMonitorDisplayName(monitor)).reset().toString());
 
 		// Attributes
-		printAttributes(monitor, indentation + 2);
+		printAttributes(monitor.getAttributes(), indentation + 2, ATTRIBUTES_HEADER);
+
+		final Resource resource = monitor.getResource();
+		if (resource != null) {
+			// Resource
+			printAttributes(resource.getAttributes(), indentation + 2, RESOURCE_HEADER);
+		}
 
 		// Metrics
 		printMetrics(monitor, indentation + 2);
@@ -199,10 +215,10 @@ private void print(final MonitorChildren monitorChildren, final int indentation)
 	}
 
 	/**
-	 * Print the metrics associated to the given monitor
+	 * Print the metrics associated to the given monitor.
 	 *
-	 * @param monitor     Monitor instance whose metrics must be printed
-	 * @param indentation How much indentation to use
+	 * @param monitor     Monitor instance whose metrics must be printed.
+	 * @param indentation How much indentation to use.
 	 */
 	void printMetrics(final Monitor monitor, final int indentation) {
 		// Get the metrics
@@ -351,24 +367,24 @@ private String getMonitorDisplayName(final Monitor monitor) {
 	}
 
 	/**
-	 * Print the attributes associated to the given monitor
+	 * Print the given attributes.
 	 *
-	 * @param monitor     The monitor whose attributes must be printed
-	 * @param indentation How much indentation to use
+	 * @param attributes  The attributes to be printed.
+	 * @param indentation How much indentation to use.
+	 * @param header      The header to be printed.
 	 */
-	void printAttributes(final Monitor monitor, final int indentation) {
+	void printAttributes(final Map<String, String> attributes, final int indentation, final String header) {
 		// Print a new line
 		printWriter.println();
 
 		// Add the margin
 		addMargin(indentation);
 
 		// Add the header
-		printWriter.println("Attributes:");
+		printWriter.println(header);
 
 		// Iterate through the attributes, printing each attribute name along with its corresponding value
-		monitor
-			.getAttributes()
+		attributes
 			.entrySet()
 			.stream()
 			.filter(entry -> shouldDisplayKey(entry.getKey()))