Problem open_file_cache directive and brotli_static on

[kvakanet]

Hello!

1. Created precompressed files .br
2. Set in nginx

brotli_static on;
open_file_cache max=2048 inactive=20s;

3. Sent request:
   curl https://example.ru/bitrix/js/ui/bootstrap4/css/bootstrap.min.css -I -A curl-Bortli -H 'Accept-Encoding: br'
   and got response

server: nginx
date: Fri, 24 Jul 2020 06:16:29 GMT
content-type: text/css
content-length: 140936
last-modified: Wed, 22 Jul 2020 12:07:04 GMT
etag: "5f182be8-22688"
expires: Fri, 31 Jul 2020 06:16:29 GMT
cache-control: max-age=604800
accept-ranges: bytes

but if you check response several times:

server: nginx
date: Fri, 24 Jul 2020 06:19:37 GMT
content-type: text/css
content-length: 15812
last-modified: Wed, 22 Jul 2020 12:07:04 GMT
etag: "5f182be8-3dc4"
content-encoding: br
expires: Fri, 31 Jul 2020 06:19:37 GMT
cache-control: max-age=604800

and so with a probability of 50%

4. If enable in nginx gzip_static on and create precompressed files .gz and send request
   curl https://example.ru/bitrix/js/ui/bootstrap4/css/bootstrap.min.css -I -A curl-Gzip -H 'Accept-Encoding: gzip'
5. Then get response

server: nginx
date: Fri, 24 Jul 2020 06:22:53 GMT
content-type: text/css
content-length: 20942
last-modified: Fri, 24 Jul 2020 03:17:35 GMT
etag: "5f1a52cf-51ce"
content-encoding: gzip
expires: Fri, 31 Jul 2020 06:22:53 GMT
cache-control: max-age=604800

100% every time.

6. If remove from nginx open_file_cache max=2048 inactive=20s;
   And send request
   curl https://example.ru/bitrix/js/ui/bootstrap4/css/bootstrap.min.css -I -A curl-Bortli -H 'Accept-Encoding: br'
   Then Response:

HTTP/2 200 
server: nginx
date: Fri, 24 Jul 2020 06:28:43 GMT
content-type: text/css
content-length: 15812
last-modified: Wed, 22 Jul 2020 12:07:04 GMT
etag: "5f182be8-3dc4"
content-encoding: br
expires: Fri, 31 Jul 2020 06:28:43 GMT
cache-control: max-age=604800

100% every time

7. Ok. I created patch

diff -ruN orig/static/ngx_http_brotli_static_module.c my/static/ngx_http_brotli_static_module.c                                                                                                                    
--- orig/static/ngx_http_brotli_static_module.c 2020-04-23 13:55:31.000000000 +0300                                                                                                                                
+++ my/static/ngx_http_brotli_static_module.c   2020-07-23 18:37:00.978000000 +0300                                                                                                                                
@@ -178,7 +178,9 @@                                                                                                                                                                                                
   if (last == NULL) return NGX_HTTP_INTERNAL_SERVER_ERROR;                                                                                                                                                        
   /* +1 for reinstating the terminating 0. */                                                                                                                                                                     
   ngx_cpystrn(last, kSuffix, kSuffixLen + 1);                                                                                                                                                                     
-  path.len += kSuffixLen;                                                                                                                                                                                         
+  /* Kuka Patch for work with open_file_cache like gzip_static */                                                                                                                                               
+  path.len = last - path.data;                                                                                                                                                                                    
+                                                                                                                                                                                                                  
                                                                                                                                                                                                                   
   log = req->connection->log;                                                                                                                                                                                     
   ngx_log_debug1(NGX_LOG_DEBUG_HTTP, log, 0, "http filename: \"%s\"",                                                                                                                                             

compile dynamic module and check again with settings nginx open_file_cache max=2048 inactive=20s;
Sent request:
curl https://example.ru/bitrix/js/ui/bootstrap4/css/bootstrap.min.css?1595419624140936 -I -A curl-Bortli -H 'Accept-Encoding: br'
Then response:

HTTP/2 200 
server: nginx
date: Fri, 24 Jul 2020 06:34:50 GMT
content-type: text/css
content-length: 15812
last-modified: Wed, 22 Jul 2020 12:07:04 GMT
etag: "5f182be8-3dc4"
content-encoding: br
expires: Fri, 31 Jul 2020 06:34:50 GMT
cache-control: max-age=604800

100% every time like gzip_static
8. But there is the problem with my patch. If I add open_file_cache_errors on; setting to nginx and request html page with many resources
then sometimes I got 404 error for resources (.png).
If I set open_file_cache_errors off; the everything works fine.