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From Greg O'Rawe <Greg.O'R...@owmobility.com>
Subject ATS without DNS
Date Mon, 09 Mar 2015 17:44:50 GMT
Hi,

I have a deployment of ATS 3.2.0 as a forward proxy where there is no access to DNS (no nameserver
entry in the /etc/resolv.conf file). The origin server IP address is normally supplied by
a request header which calls the API to set the target address but in some cases the header
is not present. The setup is not transparent so the client destination IP address is that
of the ATS and so can't be used, resulting in DNS lookups.

DNS lookups fail as no DNS, but appear to go into a retry loop, before ATS then attempts DNS
failover, but as there are no nameservers configured, this doesn't seem to work properly,
and it gets into an infinite loop of trying to failover and logging failure messages.

Mar 09 15:12:45 - INFO - [Mar  9 15:12:45.652] Server {0x2b71ac0a52c0} WARNING: failover:
connection to DNS server 127.0.0.1 lost, retrying
Mar 09 15:12:45 - INFO - [Mar  9 15:12:45.663] Server {0x2b71ac0a52c0} WARNING: failover:
connection to DNS server 127.0.0.1 lost, retrying
Mar 09 15:12:45 - INFO - [Mar  9 15:12:45.674] Server {0x2b71ac0a52c0} WARNING: failover:
connection to DNS server 127.0.0.1 lost, retrying
Mar 09 15:12:45 - INFO - [Mar  9 15:12:45.685] Server {0x2b71ac0a52c0} WARNING: failover:
connection to DNS server 127.0.0.1 lost, retrying
...

While the request itself times out, these messages are logged every 11 milliseconds or so
until the process is stopped.

Is there a way to stop this happening? ATS seems to be trying to fail over DNS even when there
is nothing configured in terms of nameservers:
CONFIG proxy.config.dns.round_robin_nameservers INT 0
CONFIG proxy.config.dns.nameservers STRING NULL

Is there a way to disable DNS lookups completely? There are other DNS-related parameters but
none of them seem to do that (there is proxy.config.http.no_dns_just_forward_to_parent but
it doesn't seem to change anything).

Thanks
Greg


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