in_tail: fix symlink log rotation for stat(2) backend on Linux (#2052)

When compiled with FLB_HAVE_INOTIFY=no for linux records were continuously resent if the files in PATH are symlinks. This patch ensures the fs_stat file monitoring correctly handles symlinks when checking for file rotations. The issue was found when running fluentbit as a daemonset in kubernetes where all files in /var/log/containers/* are symlinks. This patch was tested by forwarding 1M records of 1K size when compiled with both FLB_HAVE_INOTIFY=no/yes and verifying the output metrics reported exactly 1M records. The test was executed by running a container logging to stdout in a kubernetes cluster where symlinks are the target input. Further docker was configured to rotate logs at 10M to ensure multiple file rotations occurred. Signed-off-by: Zack Wine <[email protected]>
fluent · May 1, 2020 · 0a05f22 · 0a05f22
1 parent b0baec3
commit 0a05f22
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Showing 3 changed files with 4 additions and 4 deletions.
diff --git a/plugins/in_tail/tail_file.c b/plugins/in_tail/tail_file.c
@@ -819,7 +819,7 @@ void flb_tail_file_remove(struct flb_tail_file *file)
 
     flb_free(file->buf_data);
     flb_free(file->name);
-#if !defined(__linux__)
+#if !defined(__linux__) || !defined(FLB_HAVE_INOTIFY)
     flb_free(file->real_name);
 #endif
 
@@ -1121,7 +1121,7 @@ int flb_tail_file_name_dup(char *path, struct flb_tail_file *file)
     }
     file->name_len = strlen(file->name);
 
-#if !defined(__linux__)
+#if !defined(__linux__) || !defined(FLB_HAVE_INOTIFY)
     if (file->real_name) {
         flb_free(file->real_name);
     }

diff --git a/plugins/in_tail/tail_file.h b/plugins/in_tail/tail_file.h
@@ -51,7 +51,7 @@ static inline int flb_tail_file_name_cmp(char *name,
 static inline int flb_tail_target_file_name_cmp(char *name,
                                                 struct flb_tail_file *file)
 {
-#if defined(__linux__)
+#if defined(__linux__) && defined(FLB_HAVE_INOTIFY)
     return strcmp(name, file->name);
 #elif defined(FLB_SYSTEM_WINDOWS)
     return _stricmp(name, file->real_name);

diff --git a/plugins/in_tail/tail_file_internal.h b/plugins/in_tail/tail_file_internal.h
@@ -44,7 +44,7 @@ struct flb_tail_file {
     ino_t inode;
 #endif
     char *name;                 /* target file name given by scan routine */
-#if !defined(__linux)
+#if !defined(__linux) || !defined(FLB_HAVE_INOTIFY)
     char *real_name;            /* real file name in the file system */
 #endif
     size_t name_len;