guests/linux: Update insert_public_key cap to be one command

plugins/guests/linux/cap/insert_public_key.rb

@@ -1,19 +1,29 @@
-require "vagrant/util/shell_quote"
-
 module VagrantPlugins
   module GuestLinux
     module Cap
       class InsertPublicKey
         def self.insert_public_key(machine, contents)
+          comm = machine.communicate
           contents = contents.chomp
-          contents = Vagrant::Util::ShellQuote.escape(contents, "'")
 
-          machine.communicate.tap do |comm|
-            comm.execute("mkdir -p ~/.ssh")
-            comm.execute("chmod 0700 ~/.ssh")
-            comm.execute("printf '#{contents}\\n' >> ~/.ssh/authorized_keys")
-            comm.execute("chmod 0600 ~/.ssh/authorized_keys")
+          remote_path = "/tmp/vagrant-authorized-keys-#{Time.now.to_i}"
+          Tempfile.open("vagrant-linux-insert-public-key") do |f|
+            f.binmode
+            f.write(contents)
+            f.fsync
+            f.close
+            comm.upload(f.path, remote_path)
           end
+
+          comm.execute <<-EOH.gsub(/^ {12}/, '')
+            mkdir -p ~/.ssh
+            chmod 0700 ~/.ssh
+            cat '#{remote_path}' >> ~/.ssh/authorized_keys
+            chmod 0600 ~/.ssh/authorized_keys
+
+            # Remove the temporary file
+            rm -f '#{remote_path}'
+          EOH
         end
       end
     end

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

@@ -0,0 +1,32 @@
+require_relative "../../../../base"
+
+describe "VagrantPlugins::GuestLinux::Cap::InsertPublicKey" 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 ".insert_public_key" do
+    let(:cap) { caps.get(:insert_public_key) }
+
+    it "inserts the public key" do
+      cap.insert_public_key(machine, "ssh-rsa ...")
+      expect(comm.received_commands[0]).to match(/mkdir -p ~\/.ssh/)
+      expect(comm.received_commands[0]).to match(/chmod 0700 ~\/.ssh/)
+      expect(comm.received_commands[0]).to match(/cat '\/tmp\/vagrant-(.+)' >> ~\/.ssh\/authorized_keys/)
+      expect(comm.received_commands[0]).to match(/chmod 0600 ~\/.ssh\/authorized_keys/)
+    end
+  end
+end