From 3de6f0b8175c8a08da1974d6b6e9634075244a06 Mon Sep 17 00:00:00 2001
From: Jesse Szwedko <jesse.szwedko@datadoghq.com>
Date: Fri, 28 Jun 2024 12:21:20 -0400
Subject: [PATCH] enhancement(demo_logs source): Add `host` to emitted logs
 (#20754)

I think it's reasonable for this field to be set by default.

Closes: https://github.com/vectordotdev/vector/issues/20726

Signed-off-by: Jesse Szwedko <jesse.szwedko@datadoghq.com>
---
 changelog.d/demo_logs_host.enhancement.md |  2 ++
 src/sources/demo_logs.rs                  | 25 +++++++++++++++++++++++
 2 files changed, 27 insertions(+)
 create mode 100644 changelog.d/demo_logs_host.enhancement.md

diff --git a/changelog.d/demo_logs_host.enhancement.md b/changelog.d/demo_logs_host.enhancement.md
new file mode 100644
index 0000000000000..80a663fb7c336
--- /dev/null
+++ b/changelog.d/demo_logs_host.enhancement.md
@@ -0,0 +1,2 @@
+The `demo_logs` source now adds `host` (or the configured `log_schema.host_key`) with the value of
+`localhost` to emitted logs.
diff --git a/src/sources/demo_logs.rs b/src/sources/demo_logs.rs
index 6460147fe6c23..f2087360264e1 100644
--- a/src/sources/demo_logs.rs
+++ b/src/sources/demo_logs.rs
@@ -261,6 +261,13 @@ async fn demo_logs_source(
                             path!("service"),
                             "vector",
                         );
+                        log_namespace.insert_source_metadata(
+                            DemoLogsConfig::NAME,
+                            log,
+                            Some(LegacyKey::InsertIfEmpty(path!("host"))),
+                            path!("host"),
+                            "localhost",
+                        );
 
                         event
                     });
@@ -483,6 +490,24 @@ mod tests {
         assert!(duration >= Duration::from_secs(2));
     }
 
+    #[tokio::test]
+    async fn host_is_set() {
+        let host_key = log_schema().host_key().unwrap().to_string();
+        let mut rx = runit(
+            r#"format = "syslog"
+            count = 5"#,
+        )
+        .await;
+
+        let event = match poll!(rx.next()) {
+            Poll::Ready(event) => event.unwrap(),
+            _ => unreachable!(),
+        };
+        let log = event.as_log();
+        let host = log[&host_key].to_string_lossy();
+        assert_eq!("localhost", host);
+    }
+
     #[tokio::test]
     async fn apache_common_format_generates_output() {
         let mut rx = runit(