Validate powershell prior to powershell use

Adds powershell validation to ensure powershell is available on
the PATH and checks powershell version to ensure meets the
defined minimum powershell version.

lib/vagrant/errors.rb

@@ -536,6 +536,14 @@ module Vagrant
       error_key(:requires_directory, "vagrant.actions.general.package")
     end
 
+    class PowerShellNotFound < VagrantError
+      error_key(:powershell_not_found)
+    end
+
+    class PowerShellInvalidVersion < VagrantError
+      error_key(:powershell_invalid_version)
+    end
+
     class ProviderCantInstall < VagrantError
       error_key(:provider_cant_install)
     end

lib/vagrant/util/powershell.rb

@@ -8,8 +8,15 @@ module Vagrant
     # This is primarily a convenience wrapper around Subprocess that
     # properly sets powershell flags for you.
     class PowerShell
+      # NOTE: Version checks are only on Major
+      MINIMUM_REQUIRED_VERSION = 3
+
+      # @return [Boolean] powershell executable available on PATH
       def self.available?
-        !!Which.which("powershell")
+        if !defined?(@_powershell_available)
+          @_powershell_available = !!Which.which("powershell")
+        end
+        @_powershell_available
       end
 
       # Execute a powershell script.
@@ -17,6 +24,7 @@ module Vagrant
       # @param [String] path Path to the PowerShell script to execute.
       # @return [Subprocess::Result]
       def self.execute(path, *args, **opts, &block)
+        validate_install!
         command = [
           "powershell",
           "-NoLogo",
@@ -39,6 +47,7 @@ module Vagrant
       # @param [String] command PowerShell command to execute.
       # @return [Subprocess::Result]
       def self.execute_cmd(command)
+        validate_install!
         c = [
           "powershell",
           "-NoLogo",
@@ -58,19 +67,39 @@ module Vagrant
       #
       # @return [String]
       def self.version
-        command = [
-          "powershell",
-          "-NoLogo",
-          "-NoProfile",
-          "-NonInteractive",
-          "-ExecutionPolicy", "Bypass",
-          "-Command",
-          "$PSVersionTable.PSVersion.Major"
-        ].flatten
+        if !defined?(@_powershell_version)
+          command = [
+            "powershell",
+            "-NoLogo",
+            "-NoProfile",
+            "-NonInteractive",
+            "-ExecutionPolicy", "Bypass",
+            "-Command",
+            "$PSVersionTable.PSVersion.Major"
+          ].flatten
 
-        r = Subprocess.execute(*command)
-        return nil if r.exit_code != 0
-        return r.stdout.chomp
+          r = Subprocess.execute(*command)
+          @_powershell_version = r.exit_code != 0 ? nil : r.stdout.chomp
+        end
+        @_powershell_version
+      end
+
+      # Validates that powershell is installed, available, and
+      # at or above minimum required version
+      #
+      # @return [Boolean]
+      # @raises []
+      def self.validate_install!
+        if !defined?(@_powershell_validation)
+          raise Errors::PowerShellNotFound if !available?
+          if version.to_i < MINIMUM_REQUIRED_VERSION
+            raise Errors::PowerShellInvalidVersion,
+              minimum_version: MINIMUM_REQUIRED_VERSION,
+              installed_version: version ? version : "N/A"
+          end
+          @_powershell_validation = true
+        end
+        @_powershell_validation
       end
     end
   end

templates/locales/en.yml

@@ -1051,6 +1051,17 @@ en:
           %{error_msg}
 
         Source: %{source}
+      powershell_not_found: |-
+        Failed to locate the powershell executable on the available PATH. Please
+        ensure powershell is installed and available on the local PATH, then
+        run the command again.
+      powershell_invalid_version: |-
+        The version of powershell currently installed on this host is less than
+        the required minimum version. Please upgrade the installed version of
+        powershell to the minimum required version and run the command again.
+
+          Installed version: %{installed_version}
+          Minimum required version: %{minimum_version}
       pushes_not_defined: |-
         The Vagrantfile does not define any 'push' strategies. In order to use
         `vagrant push`, you must define at least one push strategy: