[clamav-users] local server takes time to update clamav db

[Dave Warren]

On 2020-12-11 08:51, Paul Kosinski via clamav-users wrote:
> "The whole CVD filename is not versioned (always "daily.cvd") which is
> why the CloudFlare caching issue may result in serving the previous
> version."
> 
> HTML filenames for Web pages are not versioned either. Does this mean
> that CDNs like Cloudflare often serve up obsolete Web pages? If so, does
> nobody notice (and complain)?
> 
> A delay of an hour could have an adverse effect on online commerce,
> especially during the busy holiday season.

By default Cloudflare does not cache HTML. Cloudflare also respects 
cache-control headers, which is the normal mechanism used for websites 
which want caching, but only to a point.

Cloudflare also has an API to clear the cache (at least by URI, or 
everything, and possibly more depending on the particular options 
offered by your plan). But in practice clearing the cache is not 
completely reliable and seems to be intended for cases where it is 
strictly needed and not for every "I updated this file" situation. I 
have the impression that this applies when using Cloudflare's tiered 
caching, my idle speculation wonders if perhaps this is a timing issue, 
where server #1 clears the cache, processes a request for the file which 
it obtains from server #2 all before server #2 clears the file from 
cache and then processes a request by pulling it from server #1.

 From a ClamAV perspective, one solution to solve this would be to call 
daily.cvd?version=26013 -- Note that the underlying web server could 
ignore the version parameter completely, but this would ensure that each 
Cloudflare cache retrieves a fresh version of the file and negates the 
need to push a cache clear message at all. If ClamAV's server serves an 
outdated version of the file then it would still get cached, but this 
would defeat any caching within Cloudflare for new versions as they're 
released.