feat(internal): Add VECTOR_HOSTNAME env variable

changelog.d/21789_add_vector_hostname_env_variable.enhancement.md

@@ -0,0 +1,4 @@
+Add VECTOR_HOSTNAME env variable to override the hostname used in the Vector events and internal metrics.
+This is useful when Vector is running on a system where the hostname is not meaningful, e.g., in a container (Kubernetes).
+
+authors: nabokihms

src/lib.rs

@@ -198,7 +198,12 @@ pub mod built_info {
 
 /// Returns the host name of the current system.
 pub fn get_hostname() -> std::io::Result<String> {
-    Ok(hostname::get()?.to_string_lossy().into())
+    let hostname = option_env!("VECTOR_HOSTNAME").unwrap_or("");
+    Ok(if !hostname.is_empty() {
+        hostname.to_string()
+    } else {
+        hostname::get()?.to_string_lossy().into()
+    })
 }
 
 /// Spawn a task with the given name. The name is only used if

website/cue/reference/cli.cue

@@ -595,6 +595,23 @@ cli: {
 				"""
 			type: string: default: null
 		}
+		VECTOR_HOSTNAME: {
+			description: """
+			  Overrides the hostname used in Vector's logs and metrics.
+			  This is useful when running Vector in a container or on other systems where the hostname is not meaningful.
+
+			  The example of how it can be used in Kubernetes pod template:
+
+			  ```yaml
+			  env:
+			  - name: VECTOR_HOSTNAME
+			    valueFrom:
+			      fieldRef:
+			        fieldPath: spec.nodeName
+			  ```
+			  """
+			type: string: default: null
+		}
 		VECTOR_LOG: {
 			description: "Vector's log level. Each log level includes messages from higher priority levels."
 			type: string: {