fix(coreos-base/oem-vagrant): Rework network configuration code.

- Only write configs for static networks, DHCP will work by default.
 - Match interfaces by MAC address if possible.
 - Use the configured netmask instead of always using a /24
 - Define default addresses in /etc/environment based on the type of
   network. Now using both a private and a public network works!

sdk_container/src/third_party/coreos-overlay/coreos-base/oem-vagrant/files/box/configure_networks.rb

@@ -7,11 +7,17 @@
 
 require 'tempfile'
 require 'ipaddr'
+require 'log4r'
 require Vagrant.source_root.join("plugins/guests/coreos/cap/configure_networks.rb")
 
 BASE_CLOUD_CONFIG = <<EOF
 #cloud-config
 
+write_files:
+  - path: /etc/environment
+    content: |
+      COREOS_PUBLIC_IPV4=%s
+      COREOS_PRIVATE_IPV4=%s
 coreos:
     units:
 EOF
@@ -21,7 +27,7 @@ NETWORK_UNIT = <<EOF
         runtime: no
         content: |
           [Match]
-          Name=%s
+          %s
 
           [Network]
           Address=%s
@@ -38,31 +44,43 @@ module VagrantPlugins
   module GuestCoreOS
     module Cap
       class ConfigureNetworks
-        include Vagrant::Util
+        @@logger = Log4r::Logger.new("vagrant::guest::coreos::configure_networks")
 
         def self.configure_networks(machine, networks)
-          cfg = BASE_CLOUD_CONFIG
-          machine.communicate.tap do |comm|
+          public_ipv4, private_ipv4 = get_environment_ips(machine, "127.0.0.1")
+          cfg = BASE_CLOUD_CONFIG % [public_ipv4, private_ipv4]
 
-            # Read network interface names
-            interfaces = []
-            comm.sudo("ifconfig | grep enp0 | cut -f1 -d:") do |_, result|
-              interfaces = result.split("\n")
+          # Define network units by mac address if possible.
+          match_rules = {}
+          if false
+            #if machine.provider.capability?(:nic_mac_addresses)
+            # untested, required feature hasn't made it into a release yet
+            match_rules = match_by_mac(machine)
+          else
+            match_rules = match_by_name(machine)
           end
 
-            # Configure interfaces
-            # FIXME: fix matching of interfaces with IP adresses
+          @@logger.debug("Networks: #{networks.inspect}")
+          @@logger.debug("Interfaces: #{match_rules.inspect}")
+
+          # Generate any static networks, let DHCP handle the rest
           networks.each do |network|
-              iface_num = network[:interface].to_i
-              iface_name = interfaces[iface_num]
-              cidr = IPAddr.new('255.255.255.0').to_cidr
-              address = "%s/%s" % [network[:ip], cidr]
-              unit_name = "50-%s.network" % [iface_name]
-              unit = NETWORK_UNIT % [unit_name, iface_name, address]
+            next if network[:type].to_sym != :static
+            interface = network[:interface].to_i
+            unit_name = "50-vagrant%d.network" % [interface]
 
-              cfg = "#{cfg}#{unit}"
+            match = match_rules[interface]
+            if match.nil?
+                @@logger.warn("Could not find match rule for network #{network.inspect}")
+                next
             end
 
+            cidr = IPAddr.new(network[:netmask]).to_cidr
+            address = "%s/%s" % [network[:ip], cidr]
+            cfg << NETWORK_UNIT % [unit_name, match, address]
+          end
+
+          machine.communicate.tap do |comm|
             temp = Tempfile.new("coreos-vagrant")
             temp.binmode
             temp.write(cfg)
@@ -74,6 +92,51 @@ module VagrantPlugins
             comm.sudo("systemctl start system-cloudinit@#{path_esc}.service")
           end
         end
+
+        # Find IP addresses to export in /etc/environment. This step
+        # must be performed here because that file must be written even
+        # if there are no additional networks configured.
+        def self.get_environment_ips(machine, default)
+          public_ipv4 = nil
+          private_ipv4 = nil
+
+          machine.config.vm.networks.each do |type, options|
+            next if !options[:ip]
+            if type == :public_network
+              public_ipv4 = options[:ip]
+            elsif type == :private_network
+              private_ipv4 = options[:ip]
+            end
+          end
+
+          # Fall back to localhost if no networks are configured.
+          private_ipv4 ||= default
+          public_ipv4 ||= private_ipv4
+          return [public_ipv4, private_ipv4]
+        end
+
+        def self.match_by_name(machine)
+          match = {}
+          machine.communicate.tap do |comm|
+            comm.sudo("ifconfig -a | grep ^en | cut -f1 -d:") do |_, result|
+              result.split("\n").each_with_index do |name, interface|
+                match[interface] = "Name=#{name}"
+              end
+            end
+          end
+          match
+        end
+
+        def self.match_by_mac(machine)
+          match = {}
+          macs = machine.provider.capability(:nic_mac_addresses)
+          macs.each do |adapter, address|
+            # The adapter list from VirtualBox is 1 indexed instead of 0
+            interface = adapter.to_i - 1
+            match[interface] = "MACAddress=#{address}"
+          end
+          match
+        end
       end
     end
   end