Truncate K8s event message if it is too long

CHANGELOG.md

@@ -4,11 +4,15 @@ All notable changes to this project will be documented in this file.
 
 ## [Unreleased]
 
+### Changed
+- Reported K8s events are now limited to 1024 bytes ([#327]).
+
 ### Removed
 - `Client::set_condition` ([#326]).
 - `Error` variants that are no longer used ([#326]).
 
 [#326]: https://github.com/stackabletech/operator-rs/pull/326
+[#327]: https://github.com/stackabletech/operator-rs/pull/327
 
 ## [0.11.0] - 2022-02-17
 

src/logging/k8s_events.rs

@@ -14,7 +14,7 @@ use super::controller::ReconcilerError;
 /// Converts an [`Error`] into a publishable Kubernetes [`Event`]
 fn error_to_event<E: ReconcilerError>(err: &E) -> Event {
     // Walk the whole error chain, so that we get all the full reason for the error
-    let full_msg = {
+    let mut full_msg = {
         use std::fmt::Write;
         let mut buf = err.to_string();
         let mut err: &dyn Error = err;
@@ -28,6 +28,7 @@ fn error_to_event<E: ReconcilerError>(err: &E) -> Event {
             }
         }
     };
+    message::truncate_with_ellipsis(&mut full_msg, 1024);
     Event {
         type_: EventType::Warning,
         reason: err.category().to_string(),
@@ -77,6 +78,73 @@ pub fn publish_controller_error_as_k8s_event<ReconcileErr, QueueErr>(
     );
 }
 
+mod message {
+    /// Ensures that `msg` is at most `max_len` _bytes_ long
+    ///
+    /// If `msg` is longer than `max_len` then the extra text is replaced with an ellipsis.
+    pub fn truncate_with_ellipsis(msg: &mut String, max_len: usize) {
+        const ELLIPSIS: char = '…';
+        const ELLIPSIS_LEN: usize = ELLIPSIS.len_utf8();
+        let len = msg.len();
+        if len > max_len {
+            msg.truncate(find_start_of_char(msg, len.saturating_sub(ELLIPSIS_LEN)));
+            if ELLIPSIS_LEN <= max_len {
+                msg.push(ELLIPSIS);
+            }
+        }
+    }
+
+    fn find_start_of_char(s: &str, mut pos: usize) -> usize {
+        loop {
+            if s.is_char_boundary(pos) {
+                break pos;
+            }
+            pos -= 1;
+        }
+    }
+
+    #[cfg(test)]
+    mod tests {
+        use crate::logging::k8s_events::message::find_start_of_char;
+
+        use super::truncate_with_ellipsis;
+
+        #[test]
+        fn truncate_should_be_noop_if_string_fits() {
+            let mut x = "hello".to_string();
+            truncate_with_ellipsis(&mut x, 5);
+            assert_eq!(&x, "hello");
+        }
+
+        #[test]
+        fn truncate_should_ellipsize_large_string() {
+            let mut x = "hello".to_string();
+            truncate_with_ellipsis(&mut x, 4);
+            assert_eq!(&x, "he…");
+        }
+
+        #[test]
+        fn truncate_should_ellipsize_emoji() {
+            let mut x = "hello🙋".to_string();
+            truncate_with_ellipsis(&mut x, 8);
+            assert_eq!(&x, "hello…");
+        }
+
+        #[test]
+        fn find_start_of_char_should_be_noop_for_ascii() {
+            assert_eq!(find_start_of_char("hello", 2 /* l */), 2);
+        }
+
+        #[test]
+        fn find_start_of_char_should_find_start_of_emoji() {
+            assert_eq!(
+                find_start_of_char("hello🙋", 7 /* in the middle of the emoji */),
+                5
+            );
+        }
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use k8s_openapi::api::core::v1::ConfigMap;