Add support for IPV6 in dns resolvers

[aledbf]

fixes kubernetes-retired/contrib#2188
fixes kubernetes-retired/contrib#2193
fixes #74

[k8s-reviewable]

This change is 

[gurvindersingh]

I am hitting the issue in my current setup, wondering if there will be a release once this patch is merged or should I for now remove ipv6 from resolv.conf ?

[aledbf]

@gurvindersingh for now remove ipv6 from resolv.conf

[gurvindersingh]

yeah that's what I did to have a workaround, but wondering about possible 0.8.4 or 0.9.0 with the fix.

[aledbf]

@gurvindersingh we are still migrating and changing the code. I thin we need a couple of weeks before a release. Apologies for the delay

[gurvindersingh]

@aledbf thanks the update. Will look forward to the next release.

[coveralls]

Coverage increased (+0.08%) to 39.847% when pulling 77608bf on aledbf:dns-resolver into 8e90fc0 on kubernetes:master.

[aledbf]

Using

core@localhost ~ $ cat /etc/resolv.conf
nameserver 8.8.8.8
nameserver 2001:4860:4860::8888

and setting dnsPolicy: Default the generated nginx.conf is:

+    access_log /var/log/nginx/access.log upstreaminfo if=$loggable;
+    error_log  /var/log/nginx/error.log notice;
+
+    resolver 8.8.8.8 [2001:4860:4860::8888] valid=30s;
+
+    # Retain the default nginx handling of requests without a "Connection" header
+    map $http_upgrade $connection_upgrade {
+        default          upgrade;
+        ''               close;
+    }

[coveralls]

Coverage increased (+0.08%) to 39.847% when pulling 61dad19 on aledbf:dns-resolver into 8e90fc0 on kubernetes:master.

[bprashanth]

Thanks, LGTM