enhancement (journald source): Add extra_journalctl_args option to …

…specify arbitrary command line arguments to journalctl (vectordotdev#18568)

* Add extra_journalctl_args configuration option to journald source.

* Change extra_journalctl_args to vector to allow multiple arguments to be added.

* Rename option to extra_args, update cue file.

* Fix coding style failing on `cargo fmt --check`.

---------

Co-authored-by: a-bali <a-bali@github.com>

src/sources/journald.rs

@@ -156,6 +156,13 @@ pub struct JournaldConfig {
     #[configurable(metadata(docs::human_name = "Data Directory"))]
     pub data_dir: Option<PathBuf>,
 
+    /// A list of extra command line arguments to pass to `journalctl`.
+    ///
+    /// If specified, it is merged to the command line arguments as-is.
+    #[serde(default)]
+    #[configurable(metadata(docs::examples = "--merge"))]
+    pub extra_args: Vec<String>,
+
     /// The systemd journal is read in batches, and a checkpoint is set at the end of each batch.
     ///
     /// This option limits the size of the batch.
@@ -297,6 +304,7 @@ impl Default for JournaldConfig {
             journalctl_path: None,
             journal_directory: None,
             journal_namespace: None,
+            extra_args: vec![],
             acknowledgements: Default::default(),
             remap_priority: false,
             log_namespace: None,
@@ -351,6 +359,7 @@ impl SourceConfig for JournaldConfig {
             self.journal_namespace.clone(),
             self.current_boot_only,
             self.since_now,
+            self.extra_args.clone(),
         );
 
         let batch_size = self.batch_size;
@@ -621,6 +630,7 @@ struct StartJournalctl {
     journal_namespace: Option<String>,
     current_boot_only: bool,
     since_now: bool,
+    extra_args: Vec<String>,
 }
 
 impl StartJournalctl {
@@ -630,13 +640,15 @@ impl StartJournalctl {
         journal_namespace: Option<String>,
         current_boot_only: bool,
         since_now: bool,
+        extra_args: Vec<String>,
     ) -> Self {
         Self {
             path,
             journal_dir,
             journal_namespace,
             current_boot_only,
             since_now,
+            extra_args,
         }
     }
 
@@ -669,6 +681,10 @@ impl StartJournalctl {
             command.arg("--since=2000-01-01");
         }
 
+        if !self.extra_args.is_empty() {
+            command.args(&self.extra_args);
+        }
+
         command
     }
 
@@ -1414,6 +1430,7 @@ mod tests {
         let current_boot_only = false;
         let cursor = None;
         let since_now = false;
+        let extra_args = vec![];
 
         let command = create_command(
             &path,
@@ -1422,6 +1439,7 @@ mod tests {
             current_boot_only,
             since_now,
             cursor,
+            extra_args,
         );
         let cmd_line = format!("{:?}", command);
         assert!(!cmd_line.contains("--directory="));
@@ -1432,6 +1450,7 @@ mod tests {
         let journal_dir = None;
         let journal_namespace = None;
         let since_now = true;
+        let extra_args = vec![];
 
         let command = create_command(
             &path,
@@ -1440,6 +1459,7 @@ mod tests {
             current_boot_only,
             since_now,
             cursor,
+            extra_args,
         );
         let cmd_line = format!("{:?}", command);
         assert!(cmd_line.contains("--since=now"));
@@ -1448,6 +1468,7 @@ mod tests {
         let journal_namespace = Some(String::from("my_namespace"));
         let current_boot_only = true;
         let cursor = Some("2021-01-01");
+        let extra_args = vec!["--merge".to_string()];
 
         let command = create_command(
             &path,
@@ -1456,12 +1477,14 @@ mod tests {
             current_boot_only,
             since_now,
             cursor,
+            extra_args,
         );
         let cmd_line = format!("{:?}", command);
         assert!(cmd_line.contains("--directory=/tmp/journal-dir"));
         assert!(cmd_line.contains("--namespace=my_namespace"));
         assert!(cmd_line.contains("--boot"));
         assert!(cmd_line.contains("--after-cursor="));
+        assert!(cmd_line.contains("--merge"));
     }
 
     fn create_command(
@@ -1471,13 +1494,15 @@ mod tests {
         current_boot_only: bool,
         since_now: bool,
         cursor: Option<&str>,
+        extra_args: Vec<String>,
     ) -> Command {
         StartJournalctl::new(
             path.into(),
             journal_dir,
             journal_namespace,
             current_boot_only,
             since_now,
+            extra_args,
         )
         .make_command(cursor)
     }

website/cue/reference/components/sources/base/journald.cue

@@ -82,6 +82,18 @@ base: components: sources: journald: configuration: {
 			items: type: string: examples: ["badservice", "sysinit.target"]
 		}
 	}
+	extra_args: {
+		description: """
+			A list of extra command line arguments to pass to `journalctl`.
+
+			If specified, it is merged to the command line arguments as-is.
+			"""
+		required: false
+		type: array: {
+			default: []
+			items: type: string: examples: ["--merge"]
+		}
+	}
 	include_matches: {
 		description: """
 			A list of sets of field/value pairs to monitor.