*: add "dns" field to the configuration

appc/cni#76 added a "dns" field in the result JSON. But before this
patch, the plugins had no way of knowing which name server to return.

There could be two ways of knowing which name server to return:
1. add it as an extra argument ("CNI_ARGS")
2. add it in the network configuration as a convenience (received via
   stdin)

I chose the second way because it is easier. In the case of rkt, it
means the user could just add the DNS name servers in
/etc/rkt/net.d/mynetwork.conf.

diff --git a/ptp.md b/ptp.md
index e7f2ffe..acde851 100644 (file)
--- a/ptp.md
+++ b/ptp.md
@@ -14,7 +14,11 @@ The traffic of the container interface will be routed through the interface of t
        "ipam": {
                "type": "host-local",
                "subnet": "10.1.1.0/24"
-       }
+       },
+       "dns": [
+               "8.8.8.8",
+               "8.8.4.4"
+       ]
 }
 
 ## Network configuration reference
@@ -24,3 +28,4 @@ The traffic of the container interface will be routed through the interface of t
 * `ipMasq` (boolean, optional): set up IP Masquerade on the host for traffic originating from this network and destined outside of it. Defaults to false.
 * `mtu` (integer, optional): explicitly set MTU to the specified value. Defaults to value chosen by the kernel.
 * `ipam` (dictionary, required): IPAM configuration to be used for this network.
+* `dns` (string array, optional): name servers to return as is in the [Result](/SPEC.md#result). Defaults to empty list.