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outdated version of the file then it would still get cached, but this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.
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