Permanent errors during offset validation should be retried

CHANGELOG.md

@@ -23,6 +23,8 @@ librdkafka v2.3.0 is a feature release:
  * Fix to add leader epoch to control messages, to make sure they're stored
    for committing even without a subsequent fetch message (#4434).
  * Fix for stored offsets not being committed if they lacked the leader epoch (#4442).
+ * Fix to ensure permanent errors during offset validation continue being retried and
+   don't cause an offset reset (#4447).
 
 
 ## Fixes
@@ -35,20 +37,21 @@ librdkafka v2.3.0 is a feature release:
 
 ### Consumer fixes
 
-  * Stored offsets were excluded from the commit if the leader epoch was
-    less than committed epoch, as it's possible if leader epoch is the default -1.
-    This didn't happen in Python, Go and .NET bindings when stored position was
-    taken from the message.
-    Solved by checking only that the stored offset is greater
-    than committed one, if either stored or committed leader epoch is -1 (#4442).
-
-
-### Consumer Fixes
-
+ * Stored offsets were excluded from the commit if the leader epoch was
+   less than committed epoch, as it's possible if leader epoch is the default -1.
+   This didn't happen in Python, Go and .NET bindings when stored position was
+   taken from the message.
+   Solved by checking only that the stored offset is greater
+   than committed one, if either stored or committed leader epoch is -1 (#4442).
  * If an OffsetForLeaderEpoch request was being retried, and the leader changed
    while the retry was in-flight, an infinite loop of requests was triggered,
    because we weren't updating the leader epoch correctly.
    Fixed by updating the leader epoch before sending the request (#4433).
+ * During offset validation a permanent error like host resolution failure
+   would cause an offset reset.
+   This isn't what's expected or what the Java implementation does.
+   Solved by retrying even in case of permanent errors (#4447).
+
 
 
 # librdkafka v2.2.0

src/rdkafka_offset.c

@@ -991,25 +991,15 @@ static void rd_kafka_toppar_handle_OffsetForLeaderEpoch(rd_kafka_t *rk,
                         rd_kafka_topic_leader_query0(rk, rktp->rktp_rkt, 1,
                                                      rd_true /* force */);
 
-                if (actions & RD_KAFKA_ERR_ACTION_RETRY) {
-                        /* No need for refcnt on rktp for timer opaque
-                         * since the timer resides on the rktp and will be
-                         * stopped on toppar remove. */
-                        rd_kafka_timer_start_oneshot(
-                            &rk->rk_timers, &rktp->rktp_validate_tmr, rd_false,
-                            500 * 1000 /* 500ms */,
-                            rd_kafka_offset_validate_tmr_cb, rktp);
-
-                } else if (actions & RD_KAFKA_ERR_ACTION_PERMANENT) {
-                        /* Permanent error */
-                        rd_kafka_offset_reset(
-                            rktp, rd_kafka_broker_id(rkb),
-                            RD_KAFKA_FETCH_POS(RD_KAFKA_OFFSET_INVALID,
-                                               rktp->rktp_leader_epoch),
-                            RD_KAFKA_RESP_ERR__LOG_TRUNCATION,
-                            "Unable to validate offset and epoch: %s",
-                            rd_kafka_err2str(err));
-                }
+                /* No need for refcnt on rktp for timer opaque
+                 * since the timer resides on the rktp and will be
+                 * stopped on toppar remove.
+                 * Retries the validation with a new call even in
+                 * case of permanent error. */
+                rd_kafka_timer_start_oneshot(
+                    &rk->rk_timers, &rktp->rktp_validate_tmr, rd_false,
+                    500 * 1000 /* 500ms */, rd_kafka_offset_validate_tmr_cb,
+                    rktp);
                 goto done;
         }
 

tests/0139-offset_validation_mock.c

@@ -140,10 +140,11 @@ static void do_test_no_duplicates_during_offset_validation(void) {
 
 
 /**
- * @brief Test that an SSL error doesn't cause an offset reset.
- *        See issue #4293.
+ * @brief Test that a permanent error doesn't cause an offset reset.
+ *        See issues #4293, #4427.
+ * @param err The error OffsetForLeaderEpoch fails with.
  */
-static void do_test_ssl_error_retried(void) {
+static void do_test_permanent_error_retried(rd_kafka_resp_err_t err) {
         rd_kafka_mock_cluster_t *mcluster;
         rd_kafka_conf_t *conf;
         const char *bootstraps;
@@ -155,7 +156,7 @@ static void do_test_ssl_error_retried(void) {
         int msg_count   = 5;
         uint64_t testid = test_id_generate();
 
-        SUB_TEST_QUICK();
+        SUB_TEST_QUICK("err: %s", rd_kafka_err2name(err));
 
         mcluster = test_mock_cluster_new(3, &bootstraps);
         rd_kafka_mock_topic_create(mcluster, topic, 1, 1);
@@ -165,10 +166,9 @@ static void do_test_ssl_error_retried(void) {
                                  "bootstrap.servers", bootstraps,
                                  "batch.num.messages", "1", NULL);
 
-        /* Make OffsetForLeaderEpoch fail with the _SSL error */
-        rd_kafka_mock_push_request_errors(mcluster,
-                                          RD_KAFKAP_OffsetForLeaderEpoch, 1,
-                                          RD_KAFKA_RESP_ERR__SSL);
+        /* Make OffsetForLeaderEpoch fail with the corresponding error code */
+        rd_kafka_mock_push_request_errors(
+            mcluster, RD_KAFKAP_OffsetForLeaderEpoch, 1, err);
 
         test_conf_init(&conf, NULL, 60);
 
@@ -434,7 +434,8 @@ int main_0139_offset_validation_mock(int argc, char **argv) {
 
         do_test_no_duplicates_during_offset_validation();
 
-        do_test_ssl_error_retried();
+        do_test_permanent_error_retried(RD_KAFKA_RESP_ERR__SSL);
+        do_test_permanent_error_retried(RD_KAFKA_RESP_ERR__RESOLVE);
 
         do_test_two_leader_changes();