provisioners/ansible: Check compatibility conflicts

Vagrant will verify that the current Ansible version does support the
requested compatibility mode (only applicable if not "auto", of course).

As mentioned in the documentation, there is no sanity checks between
`version` option and `compatibility_mode` option.

With this change, the host-based provisioner is also improved to
execute only once the "ansible" command (and store the gathered
information for multiple usages like version requirement and
compatibility checks). On the other hand, the guest-based provisioner
can still potentially execute "ansible" twice (once in the
AnsibleInstalled cap, and via "gather_ansible_version" function via
Base::set_compatibility_mode).

plugins/provisioners/ansible/errors.rb

@@ -26,6 +26,10 @@ module VagrantPlugins
       class AnsibleVersionMismatch < AnsibleError
         error_key(:ansible_version_mismatch)
       end
+
+      class AnsibleCompatibilityModeConflict < AnsibleError
+        error_key(:ansible_compatibility_mode_conflict)
+      end
     end
   end
 end

plugins/provisioners/ansible/provisioner/base.rb

@@ -46,45 +46,31 @@ module VagrantPlugins
           @environment_variables = {}
           @inventory_machines = {}
           @inventory_path = nil
+
+          @gathered_version_stdout = nil
+          @gathered_version_major = nil
+          @gathered_version = nil
         end
 
         def set_compatibility_mode
-          if config.compatibility_mode == Ansible::COMPATIBILITY_MODE_AUTO
-            detect_compatibility_mode(gather_ansible_version)
-          end
-
-          unless Ansible::COMPATIBILITY_MODES.slice(1..-1).include?(config.compatibility_mode)
-            raise "Programming Error: compatibility_mode must correctly set at this stage!"
-          end
-
-          @lexicon = ANSIBLE_PARAMETER_NAMES[config.compatibility_mode]
-        end
-
-        def detect_compatibility_mode(ansible_version_stdoutput)
-          if config.compatibility_mode != Ansible::COMPATIBILITY_MODE_AUTO
-            raise "Programming Error: detect_compatibility_mode() shouldn't have been called."
-          end
-
           begin
-            first_line = ansible_version_stdoutput.lines[0]
+            set_gathered_ansible_version(gather_ansible_version)
-            full_version = first_line.match(/ansible (\d)(\.\d+){1,}/)
+          rescue Exception => e
+            # Nothing to do here, as the fallback on safe compatibility_mode is done below
+            @logger.error("Error while gathering the ansible version: #{e.to_s}")
+          end
 
-            if full_version
+          if @gathered_version_major
-              major_version, _ = full_version.captures
+            if config.compatibility_mode == Ansible::COMPATIBILITY_MODE_AUTO
-
+              detect_compatibility_mode
-              if major_version.to_i <= 1
+            elsif @gathered_version_major.to_i < 2 && config.compatibility_mode == Ansible::COMPATIBILITY_MODE_V2_0
-                config.compatibility_mode = Ansible::COMPATIBILITY_MODE_V1_8
+              # A better version comparator will be needed
-              else
+              # when more compatibility modes come... but so far let's keep it simple!
-                config.compatibility_mode = Ansible::COMPATIBILITY_MODE_V2_0
+              raise Ansible::Errors::AnsibleCompatibilityModeConflict,
-              end
+                ansible_version: @gathered_version,
-
+                system: @control_machine,
-              @machine.env.ui.warn(I18n.t("vagrant.provisioners.ansible.compatibility_mode_warning",
+                compatibility_mode: config.compatibility_mode
-                compatibility_mode: config.compatibility_mode,
-                ansible_version: full_version) +
-              "\n")
             end
-          rescue
-            # Nothing to do here, the fallback to default compatibility_mode is done below
           end
 
           if config.compatibility_mode == Ansible::COMPATIBILITY_MODE_AUTO
@@ -92,9 +78,15 @@ module VagrantPlugins
 
             @machine.env.ui.warn(I18n.t("vagrant.provisioners.ansible.compatibility_mode_not_detected",
               compatibility_mode: config.compatibility_mode,
-              gathered_version: ansible_version_stdoutput) +
+              gathered_version: @gathered_version_stdout) +
             "\n")
           end
+
+          unless Ansible::COMPATIBILITY_MODES.slice(1..-1).include?(config.compatibility_mode)
+            raise "Programming Error: compatibility_mode must correctly set at this stage!"
+          end
+
+          @lexicon = ANSIBLE_PARAMETER_NAMES[config.compatibility_mode]
         end
 
         def check_files_existence
@@ -357,6 +349,39 @@ module VagrantPlugins
           end
         end
 
+        private
+
+        def detect_compatibility_mode
+          if !@gathered_version_major || config.compatibility_mode != Ansible::COMPATIBILITY_MODE_AUTO
+            raise "Programming Error: detect_compatibility_mode() shouldn't have been called."
+          end
+
+          if @gathered_version_major.to_i <= 1
+            config.compatibility_mode = Ansible::COMPATIBILITY_MODE_V1_8
+          else
+            config.compatibility_mode = Ansible::COMPATIBILITY_MODE_V2_0
+          end
+
+          @machine.env.ui.warn(I18n.t("vagrant.provisioners.ansible.compatibility_mode_warning",
+            compatibility_mode: config.compatibility_mode,
+            ansible_version: @gathered_version) +
+          "\n")
+        end
+
+        def set_gathered_ansible_version(stdout_output)
+          @gathered_version_stdout = stdout_output
+          if !@gathered_version_stdout.empty?
+            first_line = @gathered_version_stdout.lines[0]
+            ansible_version_pattern = first_line.match(/(^ansible\s+)(.+)$/)
+            if ansible_version_pattern
+              _, @gathered_version, _ = ansible_version_pattern.captures
+              if @gathered_version
+                @gathered_version_major = @gathered_version.match(/^(\d)\..+$/).captures[0].to_i
+              end
+            end
+          end
+        end
+
       end
     end
   end

plugins/provisioners/ansible/provisioner/guest.rb

@@ -66,19 +66,22 @@ module VagrantPlugins
           if (!config.version.empty? &&
               config.version.to_s.to_sym != :latest &&
               !@machine.guest.capability(:ansible_installed, config.version))
-            raise Ansible::Errors::AnsibleVersionMismatch, system: @control_machine, required_version: config.version.to_s
+            raise Ansible::Errors::AnsibleVersionMismatch,
+              system: @control_machine,
+              required_version: config.version,
+              current_version: @gathered_version
           end
         end
 
         def gather_ansible_version
-          raw_output = nil
+          raw_output = ""
           result = @machine.communicate.execute("ansible --version", error_check: false) do |type, output|
             if type == :stdout && output.lines[0]
               raw_output = output.lines[0]
             end
           end
           if result != 0
-            raw_output = nil
+            raw_output = ""
           end
           raw_output
         end

plugins/provisioners/ansible/provisioner/host.rb

@@ -20,9 +20,9 @@ module VagrantPlugins
           @ssh_info = @machine.ssh_info
 
           warn_for_unsupported_platform
-          check_required_ansible_version unless config.version.empty?
           check_files_existence
           set_compatibility_mode
+          check_required_ansible_version
 
           execute_ansible_galaxy_from_host if config.galaxy_role_file
           execute_ansible_playbook_from_host
@@ -39,15 +39,16 @@ module VagrantPlugins
         end
 
         def check_required_ansible_version
-          if config.version.to_s.to_sym == :latest
+          # Skip this check when not required, nor possible
-            @logger.debug("The :latest version requirement is not supported (yet) by the host-based provisioner")
+          if !@gathered_version || config.version.empty? || config.version.to_s.to_sym == :latest
             return
           end
 
-          @logger.info("Checking for Ansible version on Vagrant host...")
+          if config.version != @gathered_version
-          found_version = gather_ansible_version
+            raise Ansible::Errors::AnsibleVersionMismatch,
-          if (!found_version || "ansible #{config.version}\n" != found_version.lines[0])
+              system: @control_machine,
-            raise Ansible::Errors::AnsibleVersionMismatch, system: @control_machine, required_version: config.version.to_s
+              required_version: config.version,
+              current_version: @gathered_version
           end
         end
 
@@ -105,7 +106,7 @@ module VagrantPlugins
         end
 
         def gather_ansible_version
-          raw_output = nil
+          raw_output = ""
           command = %w(ansible --version)
 
           command << {
@@ -119,7 +120,7 @@ module VagrantPlugins
               end
             end
             if result.exit_code != 0
-              raw_output = nil
+              raw_output = ""
             end
           rescue Vagrant::Errors::CommandUnavailable
             raise Ansible::Errors::AnsibleNotFoundOnHost

templates/locales/en.yml

@@ -2366,10 +2366,15 @@ en:
             https://github.com/mitchellh/vagrant
           ansible_version_mismatch: |-
             The requested Ansible version (%{required_version}) was not found on the %{system}.
-            Please check the Ansible installation on your Vagrant %{system} system,
+            Please check the Ansible installation on your Vagrant %{system} system (currently: %{current_version}),
             or adapt the `version` option of this provisioner in your Vagrantfile.
             See https://docs.vagrantup.com/v2/provisioning/ansible_common.html#version
             for more information.
+          ansible_compatibility_mode_conflict: |-
+            The requested Ansible compatibility mode (%{compatibility_mode}) is in conflict with
+            the Ansible installation on your Vagrant %{system} system (currently: %{ansible_version}).
+            See https://docs.vagrantup.com/v2/provisioning/ansible_common.html#compatibility_mode
+            for more information.
           config_file_not_found: |-
             `%{config_option}` does not exist on the %{system}: %{path}
           extra_vars_invalid: |-

test/unit/plugins/provisioners/ansible/provisioner_test.rb

@@ -313,7 +313,8 @@ VF
       valid_versions = {
         "0.6": VagrantPlugins::Ansible::COMPATIBILITY_MODE_V1_8,
         "1.9.4": VagrantPlugins::Ansible::COMPATIBILITY_MODE_V1_8,
-        "2.2.1.0": VagrantPlugins::Ansible::COMPATIBILITY_MODE_V2_0,
+        "2.5.0.0-rc1": VagrantPlugins::Ansible::COMPATIBILITY_MODE_V2_0,
+        "2.x.y.z": VagrantPlugins::Ansible::COMPATIBILITY_MODE_V2_0,
         "4.3.2.1": VagrantPlugins::Ansible::COMPATIBILITY_MODE_V2_0,
       }
       valid_versions.each_pair do |ansible_version, mode|
@@ -331,7 +332,7 @@ VF
           it "warns about compatibility mode auto-detection being used" do
             expect(machine.env.ui).to receive(:warn).with(
               I18n.t("vagrant.provisioners.ansible.compatibility_mode_warning",
-                compatibility_mode: mode, ansible_version: "ansible #{ansible_version}") +
+                compatibility_mode: mode, ansible_version: ansible_version) +
               "\n")
           end
         end
@@ -339,7 +340,7 @@ VF
 
       invalid_versions = [
         "ansible devel",
-        "ansible 2.x.y.z\n...\n",
+        "anything 1.2",
         "2.9.2.1",
       ]
       invalid_versions.each do |unknown_ansible_version|
@@ -371,6 +372,7 @@ VF
         config.compatibility_mode = VagrantPlugins::Ansible::COMPATIBILITY_MODE_V1_8
       end
 
+      it_should_check_ansible_version
       it_should_create_and_use_generated_inventory
 
       it "doesn't warn about compatibility mode auto-detection" do
@@ -381,6 +383,7 @@ VF
     context "with compatibility_mode '#{VagrantPlugins::Ansible::COMPATIBILITY_MODE_V2_0}'" do
       before do
         config.compatibility_mode = VagrantPlugins::Ansible::COMPATIBILITY_MODE_V2_0
+        allow(subject).to receive(:gather_ansible_version).and_return("ansible 2.3.0.0\n...\n")
       end
 
       it_should_create_and_use_generated_inventory
@@ -389,6 +392,16 @@ VF
         expect(machine.env.ui).to_not receive(:warn)
       end
 
+      describe "and an incompatible ansible version" do
+        before do
+          allow(subject).to receive(:gather_ansible_version).and_return("ansible 1.9.3\n...\n")
+        end
+
+        it "raises a compatibility conflict error", skip_before: false, skip_after: true do
+          expect {subject.provision}.to raise_error(VagrantPlugins::Ansible::Errors::AnsibleCompatibilityModeConflict)
+        end
+      end
+
       describe "deprecated 'sudo' options are aliases for equivalent 'become' options" do
         before do
           # Filter the deprecation notices
@@ -413,7 +426,7 @@ VF
         config.playbook_command = "custom-ansible-playbook"
 
         # set the compatibility mode to ensure that only ansible-playbook is excuted
-        config.compatibility_mode = VagrantPlugins::Ansible::COMPATIBILITY_MODE_V2_0
+        config.compatibility_mode = VagrantPlugins::Ansible::COMPATIBILITY_MODE_V1_8
       end
 
       it "uses custom playbook_command to run playbooks" do
@@ -968,20 +981,29 @@ VF
           allow(subject).to receive(:gather_ansible_version).and_return("ansible 1.9.6\n...\n")
         end
 
-        it "raises an error about the ansible version mismatch", skip_before: true, skip_after: true do
+        it "raises an error about the ansible version mismatch", skip_before: false, skip_after: true do
-          config.finalize!
           expect {subject.provision}.to raise_error(VagrantPlugins::Ansible::Errors::AnsibleVersionMismatch)
         end
       end
 
       describe "and the installed ansible version cannot be detected" do
         before do
-          allow(subject).to receive(:gather_ansible_version).and_return(nil)
+          allow(subject).to receive(:gather_ansible_version).and_return("")
         end
 
-        it "raises an error about the ansible version mismatch", skip_before: true, skip_after: true do
+        it "skips the ansible version check and executes ansible-playbook command" do
-          config.finalize!
+          expect(Vagrant::Util::Subprocess).to receive(:execute).with('ansible-playbook', any_args).and_return(default_execute_result)
-          expect {subject.provision}.to raise_error(VagrantPlugins::Ansible::Errors::AnsibleVersionMismatch)
+        end
+      end
+
+      describe "with special value: 'latest'" do
+        before do
+          config.version = :latest
+          allow(subject).to receive(:gather_ansible_version).and_return("ansible 2.2.0.1\n...\n")
+        end
+
+        it "skips the ansible version check and executes ansible-playbook command" do
+          expect(Vagrant::Util::Subprocess).to receive(:execute).with('ansible-playbook', any_args).and_return(default_execute_result)
         end
       end
     end
@@ -1168,7 +1190,7 @@ VF
         allow(machine.ui).to receive(:warn)
 
         # Set the compatibility mode to only get the Windows warning
-        config.compatibility_mode = VagrantPlugins::Ansible::COMPATIBILITY_MODE_V2_0
+        config.compatibility_mode = VagrantPlugins::Ansible::COMPATIBILITY_MODE_V1_8
       end
 
       it "warns that Windows is not officially supported for the Ansible control machine" do

website/source/docs/provisioning/ansible_common.html.md

@@ -35,16 +35,18 @@ Some of these options are for advanced usage only and should not be used unless
 
     By default this option is set to `"auto"`. If Vagrant is not able to detect any supported Ansible version, it will falls back on the compatibility mode `"1.8"` with a warning.
 
-    <div class="alert alert-info">
+    Vagrant will error if the specified compatibility mode is incompatible with the current Ansible version.
-      <strong>Compatibility Note:</strong>
-      This option was introduced in Vagrant 2.0. Previous Vagrant versions behave like if this option was set to `"1.8"`.
-    </div>
 
     <div class="alert alert-warning">
       <strong>Attention:</strong>
       Vagrant doesn't perform any validation between the `compatibility_mode` value and the value of the [`version`](#version) option.
     </div>
 
+    <div class="alert alert-info">
+      <strong>Compatibility Note:</strong>
+      This option was introduced in Vagrant 2.0. Previous Vagrant versions behave like if this option was set to `"1.8"`.
+    </div>
+
 - `config_file` (string) - The path to an [Ansible Configuration file](https://docs.ansible.com/intro_configuration.html).
 
     By default, this option is not set, and Ansible will [search for a possible configuration file in some default locations](/docs/provisioning/ansible_intro.html#ANSIBLE_CONFIG).