Update NFS service name usage for linux hosts

Provides simple nfs service name detection via systemd or sys-v. Defaults
are provided if no match is found. Service name is defined via method
allowing derivative guests to only need to provide an updated name.

plugins/hosts/linux/cap/nfs.rb

@@ -9,25 +9,53 @@ module VagrantPlugins
       class NFS
 
         NFS_EXPORTS_PATH = "/etc/exports".freeze
+        NFS_DEFAULT_NAME_SYSTEMD = "nfs-server.service".freeze
+        NFS_DEFAULT_NAME_SYSV = "nfs-kernel-server".freeze
         extend Vagrant::Util::Retryable
 
+        def self.nfs_service_name_systemd
+          if !defined?(@_nfs_systemd)
+            result = Vagrant::Util::Subprocess.execute("systemctl", "list-units",
+              "*nfs*server*", "--no-pager", "--no-legend")
+            if result.exit_code == 0
+              @_nfs_systemd = result.stdout.to_s.split(/\s+/).first
+            end
+            if @_nfs_systemd.to_s.empty?
+              @_nfs_systemd = NFS_DEFAULT_NAME_SYSTEMD
+            end
+          end
+          @_nfs_systemd
+        end
+
+        def self.nfs_service_name_sysv
+          if !defined?(@_nfs_sysv)
+            @_nfs_sysv = Dir.glob("/etc/init.d/*nfs*server*").first.to_s
+            if @_nfs_sysv.empty?
+              @_nfs_sysv = NFS_DEFAULT_NAME_SYSV
+            else
+              @_nfs_sysv = File.basename(@_nfs_sysv)
+            end
+          end
+          @_nfs_sysv
+        end
+
         def self.nfs_apply_command(env)
           "exportfs -ar"
         end
 
         def self.nfs_check_command(env)
           if Vagrant::Util::Platform.systemd?
-            "systemctl status --no-pager nfs-server.service"
+            "systemctl status --no-pager #{nfs_service_name_systemd}"
           else
-            "/etc/init.d/nfs-kernel-server status"
+            "/etc/init.d/#{nfs_service_name_sysv} status"
           end
         end
 
         def self.nfs_start_command(env)
           if Vagrant::Util::Platform.systemd?
-            "systemctl start nfs-server.service"
+            "systemctl start #{nfs_service_name_systemd}"
           else
-            "/etc/init.d/nfs-kernel-server start"
+            "/etc/init.d/#{nfs_service_name_sysv} start"
           end
         end
 
@@ -63,7 +91,7 @@ module VagrantPlugins
           if Vagrant::Util::Platform.systemd?
             Vagrant::Util::Subprocess.execute("/bin/sh", "-c",
               "systemctl --no-pager --no-legend --plain list-unit-files --all --type=service " \
-                "| grep nfs-server.service").exit_code == 0
+                "| grep #{nfs_service_name_systemd}").exit_code == 0
           else
             Vagrant::Util::Subprocess.execute("modinfo", "nfsd").exit_code == 0 ||
               Vagrant::Util::Subprocess.execute("grep", "nfsd", "/proc/filesystems").exit_code == 0
@@ -233,6 +261,13 @@ module VagrantPlugins
         def self.nfs_running?(check_command)
           Vagrant::Util::Subprocess.execute(*Shellwords.split(check_command)).exit_code == 0
         end
+
+        # @private
+        # Reset the cached values for capability. This is not considered a public
+        # API and should only be used for testing.
+        def self.reset!
+          instance_variables.each(&method(:remove_instance_variable))
+        end
       end
     end
   end

test/unit/plugins/hosts/linux/cap/nfs_test.rb

@@ -24,15 +24,58 @@ describe VagrantPlugins::HostLinux::Cap::NFS do
     @original_exports_path = VagrantPlugins::HostLinux::Cap::NFS::NFS_EXPORTS_PATH
     VagrantPlugins::HostLinux::Cap::NFS.send(:remove_const, :NFS_EXPORTS_PATH)
     VagrantPlugins::HostLinux::Cap::NFS.const_set(:NFS_EXPORTS_PATH, tmp_exports_path.to_s)
+    allow(Vagrant::Util::Subprocess).to receive(:execute).with("systemctl", "list-units", any_args).
+      and_return(Vagrant::Util::Subprocess::Result.new(1, "", ""))
+    allow(Vagrant::Util::Platform).to receive(:systemd?).and_return(false)
   end
 
   after do
     VagrantPlugins::HostLinux::Cap::NFS.send(:remove_const, :NFS_EXPORTS_PATH)
     VagrantPlugins::HostLinux::Cap::NFS.const_set(:NFS_EXPORTS_PATH, @original_exports_path)
+    VagrantPlugins::HostLinux::Cap::NFS.reset!
     File.unlink(tmp_exports_path.to_s) if File.exist?(tmp_exports_path.to_s)
     @tmp_exports = nil
   end
 
+  describe ".nfs_service_name_systemd" do
+    let(:cap){ VagrantPlugins::HostLinux::Cap::NFS }
+
+    context "without service match" do
+      it "should use default service name" do
+        expect(cap.nfs_service_name_systemd).to eq(cap.const_get(:NFS_DEFAULT_NAME_SYSTEMD))
+      end
+    end
+
+    context "with service match" do
+      let(:custom_nfs_service_name){ "custom-nfs-server-service-name" }
+      before{ expect(Vagrant::Util::Subprocess).to receive(:execute).with("systemctl", "list-units", any_args).
+          and_return(Vagrant::Util::Subprocess::Result.new(0, custom_nfs_service_name, "")) }
+
+      it "should use the matched service name" do
+        expect(cap.nfs_service_name_systemd).to eq(custom_nfs_service_name)
+      end
+    end
+  end
+
+  describe ".nfs_service_name_sysv" do
+    let(:cap){ VagrantPlugins::HostLinux::Cap::NFS }
+
+    context "without service match" do
+      it "should use default service name" do
+        expect(cap.nfs_service_name_sysv).to eq(cap.const_get(:NFS_DEFAULT_NAME_SYSV))
+      end
+    end
+
+    context "with service match" do
+      let(:custom_nfs_service_name){ "/etc/init.d/custom-nfs-server-service-name" }
+      before{ expect(Dir).to receive(:glob).with(/.+init\.d.+/).and_return([custom_nfs_service_name]) }
+
+      it "should use the matched service name" do
+        expect(cap.nfs_service_name_sysv).to eq(File.basename(custom_nfs_service_name))
+      end
+    end
+  end
+
   describe ".nfs_check_command" do
     let(:cap){ caps.get(:nfs_check_command) }
 
@@ -44,7 +87,9 @@ describe VagrantPlugins::HostLinux::Cap::NFS do
       end
     end
     context "with systemd" do
-      before{ expect(Vagrant::Util::Platform).to receive(:systemd?).and_return(true) }
+      before do
+        expect(Vagrant::Util::Platform).to receive(:systemd?).and_return(true)
+      end
 
       it "should use systemctl" do
         expect(cap.nfs_check_command(env)).to include("systemctl")
@@ -162,6 +207,8 @@ EOH
 
     before do
       allow(ui).to receive(:info)
+      allow(Vagrant::Util::Subprocess).to receive(:execute).with("mv", any_args).
+        and_call_original
     end
 
     it "should remove entries no longer valid" do
@@ -189,6 +236,8 @@ EOH
 
     before do
       File.write(tmp_exports_path, "original content")
+      allow(Vagrant::Util::Subprocess).to receive(:execute).with("mv", any_args).
+        and_call_original
     end
 
     it "should write updated contents to file" do