* Add max upstream connections dns-proxy option
Allows defining a limit to the number of connections that can be
established with the upstream DNS host.
If left unset, there may be situations where connections fail to
establish, which causes the Transport to create an influx of connections
causing upstream to throttle our requests and triggering a runaway
effect resulting in high CPU usage. See https://github.com/cloudflare/cloudflared/issues/91
* Code review with proposed changes
* Add max upstream connections flag to tunnel flags
* Reduce DNS proxy max upstream connections default value
Reduce the default value of maximum upstream connections on the DNS
proxy to guarantee it works on single-core and other low-end hardware.
Further testing could allow for a safe increase of this value.
* Update dns-proxy flag name
Also remove `MaxUpstreamConnsFlag` const as it's no longer referenced in more than one place and to make things more consistent with how the other flags are referenced.
Co-authored-by: Adam Chalmers <achalmers@cloudflare.com>
The following UInt flags:
* Uint64 - heartbeat-count, compression-quality
* Uint - retries, port, proxy-port
were not being correctly picked from the configuration YAML
since the multi origin refactor
This is due to a limitation of the ufarve library, which we
overcome for now with handling those as Int flags.
David Jimenez
Nuno Diegues
Areg Harutyunyan
Adam Chalmers
Igor Postelnik
cthuang
Dalton
Austin Cherry