guests/linux: Always order discovered network interfaces

plugins/guests/linux/cap/network_interfaces.rb

@@ -2,6 +2,8 @@ module VagrantPlugins
   module GuestLinux
     module Cap
       class NetworkInterfaces
+        @@logger = Log4r::Logger.new("vagrant::guest::linux::network_interfaces")
+
         # Get network interfaces as a list. The result will be something like:
         #
         #   eth0\nenp0s8\nenp0s9
@@ -12,7 +14,21 @@ module VagrantPlugins
           machine.communicate.sudo("#{path} -o -0 addr | grep -v LOOPBACK | awk '{print $2}' | sed 's/://'") do |type, data|
             s << data if type == :stdout
           end
-          s.split("\n")
+          ifaces = s.split("\n")
+          @@logger.debug("Unsorted list: #{ifaces.inspect}")
+          # Break out integers from strings and sort the arrays to provide
+          # a natural sort for the interface names
+          ifaces = ifaces.map do |iface|
+            iface.scan(/(.+?)(\d+)/).flatten.map do |iface_part|
+              if iface_part.to_i.to_s == iface_part
+                iface_part.to_i
+              else
+                iface_part
+              end
+            end
+          end.sort.map(&:join)
+          @@logger.debug("Sorted list: #{ifaces.inspect}")
+          ifaces
         end
       end
     end

test/unit/plugins/guests/linux/cap/network_interfaces_test.rb

@@ -0,0 +1,48 @@
+require_relative "../../../../base"
+
+describe "VagrantPlugins::GuestLinux::Cap::NetworkInterfaces" do
+  let(:caps) do
+    VagrantPlugins::GuestLinux::Plugin
+      .components
+      .guest_capabilities[:linux]
+  end
+
+  let(:machine) { double("machine") }
+  let(:comm) { VagrantTests::DummyCommunicator::Communicator.new(machine) }
+
+  before do
+    allow(machine).to receive(:communicate).and_return(comm)
+  end
+
+  after do
+    comm.verify_expectations!
+  end
+
+  describe ".network_interfaces" do
+    let(:cap){ caps.get(:network_interfaces) }
+
+    it "sorts discovered classic interfaces" do
+      expect(comm).to receive(:sudo).and_yield(:stdout, "eth1\neth2\neth0")
+      result = cap.network_interfaces(machine)
+      expect(result).to eq(["eth0", "eth1", "eth2"])
+    end
+
+    it "sorts discovered predictable network interfaces" do
+      expect(comm).to receive(:sudo).and_yield(:stdout, "enp0s8\nenp0s3\nenp0s5")
+      result = cap.network_interfaces(machine)
+      expect(result).to eq(["enp0s3", "enp0s5", "enp0s8"])
+    end
+
+    it "sorts discovered classic interfaces naturally" do
+      expect(comm).to receive(:sudo).and_yield(:stdout, "eth1\neth2\neth12\neth0\neth10")
+      result = cap.network_interfaces(machine)
+      expect(result).to eq(["eth0", "eth1", "eth2", "eth10", "eth12"])
+    end
+
+    it "sorts discovered predictable network interfaces naturally" do
+      expect(comm).to receive(:sudo).and_yield(:stdout, "enp0s8\nenp0s3\nenp0s5\nenp0s10\nenp1s3")
+      result = cap.network_interfaces(machine)
+      expect(result).to eq(["enp0s3", "enp0s5", "enp0s8", "enp0s10", "enp1s3"])
+    end
+  end
+end