Avoid repeated Cloudflare resolve attempts when DNS over TLS is blocked #134
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When a first resolve attempt on the fallback chain (:5553) fails, the fallback plug-in of the main chain will trigger health check. By default health checks sends a request every 0.5s as long as upstream reports unhealthy (default value). Unfortuntely the fallback plug-in's health check can't be confiugred currently. Each of these health checks will trigger a 5s resolve attempt by the fallback chains forward plug-in. And since we get a health check every 0.5s, and health checks on the fallback chain are disabled, this leads to non-stop resolve attempts, forever. On-top of that, even when the primary/DHCP provided DNS server is working, the loop plug-in will trigger a first resolve attempt on the fallback chain still! This means, even with a working primary DNS sever, the fallback chain will enter a runaway loop still! This change does several things: - Handle the loop check using a template plug-in. This avoids a loop test requests to Cloudflare. With that, and a working primary DNS server, no DNS requests will get sent to Cloudflare by default. - Handle the health check of the fallback plug-in using a template plug-in. This essentially "disables" health check on the primary chains fallback plug-in (which would be the better approach, if that were possible). - Reenable health checks in the fallback chain, to avoid repeated attempts to Cloudflare when it's not available.
agners
changed the title
mdegat01
approved these changes
Apr 4, 2024
agners
changed the title
This was referenced Apr 5, 2024
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When a first resolve attempt on the fallback chain (:5553) fails, the fallback plug-in of the main chain will trigger health check. By default health checks sends a request every 0.5s as long as upstream reports unhealthy (default value). Unfortuntely the fallback plug-in's health check can't be confiugred currently.
Each of these health checks will trigger a 5s resolve attempt by the fallback chains forward plug-in. And since we get a health check every 0.5s, and health checks on the fallback chain are disabled, this leads to non-stop resolve attempts, forever.
On-top of that, even when the primary/DHCP provided DNS server is working, the loop plug-in will trigger a first resolve attempt on the fallback chain still! This means, even with a working primary DNS sever, the fallback chain will enter a runaway loop still!
This change does several things:
Fixes #90