ModPagespeedShardDomain not working for a non-optimised, sharded hostname request.

[sourabh8Webscale]

Whats is the Issue?

Requests having sharded hostname and non-optimized resources(non-pagespeed resource) are not being mapped to origin domain.

Here is a glimpse of my configuration, I have provided a detailed configuration in the last section.

    # CDN Sharding is enabled.
    ModPagespeedShardDomain http://www.example.com http://cdn1-cname.example.com/ABC,http://cdn2-cname.example.com/ABC,http://cdn3-cname.example.com/ABC
    ModPagespeedShardDomain http://www.alias-example.com http://cdn1-cname.example.com/DEF,http://cdn2-cname.example.com/DEF,http://cdn3-cname.example.com/DEF
    
    # Map origin domain.
    ModPagespeedMapOriginDomain 127.0.0.1 http://www.example.com
    ModPagespeedMapOriginDomain 127.0.0.1 http://www.alias-example.com

ABC, DEF are our checksum to map the shard request to a correct hostname or alias.

Problem statement: Requests like http://www.cdn1-cname.example.com/ABC/ex/fonts/myfont.tiff ends up at localhost with path as /ABC/ex/fonts/myfonts.tiff instead of /ex/fonts/myfonts.tiff.

What is the expected output?

I expect the URL http://www.cdn1-cname.example.com/ABC/ex/fonts/myfont.tiff to be mapped to its master domain something like http://www.example.com/ex/fonts/myfont.tiff and then should request to its origin with URL something like http://localhost/ex/fonts/myfont.tiff.

What do you see instead?

For non-optimized and sharded resource:

What I can observe is that when a request like http://www.cdn1-cname.example.com/ABC/ex/fonts/myfont.tiff reaches the Instaweb_handler, it first checks if the requests is a pagespeed original URL or if such request has already been made or if requests are a part of another request and it didn't find it to be anyone of them then it creates a URL using ap_construct_url, which is similar to the current URL. Then it registers this requests as original pagespeed request by registering it usingapr_table_setn. Then it checks if this URL is a pagespeed beacon request or if this URL is a pagespeed resource, which turns out to be false. And this marks the URL to be a non-pagespeed URL using apr_table_set. Pagespeed doesn't alter this URL and then ProxyFixupHost changes the host to www.example.com and updates the request to http://www.example.com/ABC/ex/fonts/myfont.tiff and ProxyPass directs it to balancer cluster which updates requests to http://localhost/ABC/ex/fonts/myfont.tiff`.

For optimized resource:

For example a sharded and optimized request like this http://www.cdn1-cname.example.com/ABC/ex/400x300a1.jpg.pagespeed.ic.hash.webp gets properly mapped to its master domain http://www.example.com/ex/400x300a1.jpg.pagespeed.ic.hash.webp and then it gets searched in pagespeed cache if found then it returns the resource if not then it tries to load the resource asynchronously by updating the URL to http://www.cdn1-cname.example.com/ABC/ex/1.jpg and then fetches the resource from the localhost with request http://127.0.0.1/ex/1.jpg.

On what operating system? Ubuntu 16.04.7

Which version of Apache? 2.4.43

Which version of pagespeed? v1.13.35.2

What steps will reproduce the problem?

Request a page in which there should resources which pagespeed should decide not to optimize , such as font files or small images the file formats which are failing for me are .tiff, .woff, .woff2, .png, .svg. and a few others.

This issue is coming in production where the customer site has a lot of resources but only above mentioned resources are not being handled properly.

My configuration:

<VirtualHost 127.0.0.1:80 10.12x.x.3x:80>
  ServerName cname.example.com
  Session off
  DocumentRoot lg_vhosts/cname.example.com.80/www
  AllowEncodedSlashes NoDecode
  ServerAlias cdn1-cname.example.com
  ServerAlias cdn2-cname.example.com
  ServerAlias cdn3-cname.example.com
  ModPagespeedFileCachePath /var/cache/pagespeed/cname.example.com
  ModPagespeedFileCacheSizeKb 10xxxxx
  RemoteIPInternalProxy 127.0.0.1
  LegacyTrust off
  AddOutputFilterByType DEFLATE text/html text/plain text/xml text/css text/javascript application/javascript text/javascript text/x-js text/x-javascript
  <IfModule pagespeed_module>
    ModPagespeed On
    ModPagespeedEnableFilters insert_dns_prefetch
    ModPagespeedEnableFilters add_instrumentation
    ModPagespeedUrlValuedAttribute img data-src image
    ModPagespeedFetchHttps enable
    ModPagespeedDomain www.example.com
    ModPagespeedDomain www.alias-example.com
    ModPagespeedDomain https:// www.example.com
    ModPagespeedDomain https://www.alias-example.com


    # CDN Sharding is enabled.
    ModPagespeedShardDomain http://www.example.com http://cdn1-cname.example.com/ABC,http://cdn2-cname.example.com/ABC,http://cdn3-cname.example.com/ABC
    ModPagespeedShardDomain http://www.alias-example.com http://cdn1-cname.example.com/DEF,http://cdn2-cname.example.com/DEF,http://cdn3-cname.example.com/DEF
    
    # Optimize HTTPS is enabled as well, so we need to define https shards.
    ModPagespeedShardDomain https://www.example.com https://www.cdn1-cname.example.com/ABC,https://cdn2-cname.example.com/ABC,https://cdn3-cname.example.com/ABC
    ModPagespeedShardDomain https://www.alias-example.com https://www.cdn1-cname.example.com/DEF,https://cdn2-cname.example.com/DEF,https://cdn3-cname.example.com/DEF
    # Map origin domain.
    ModPagespeedMapOriginDomain 127.0.0.1 http://www.example.com
    ModPagespeedMapOriginDomain 127.0.0.1 http://www.alias-example.com

  </IfModule>
  ProxyFixupHost www.example.com
  SetEnvIfExpr true !proxy-initial-not-pooled
  <Proxy balancer://cluster_0_0>
    BalancerMember http://127.0.0.1:80
    ProxySet lbmethod=bybusyness
  </Proxy>
  ProxyPass / balancer://cluster_0_0/
  RequestHeader set X-Forwarded-Proto http
  Protocols http/1.1
</VirtualHost>

Things I have tried:

1. I have experimented with the configuration with the following changes added ModPagespeedShardDomain 127.0.0.1 www.cdn1-cname.example.com/ABC www.example.com to vhost file, but it gave me similar results.