Validate Vagrantfile in CI unit-tests (#4642)

* Validate vagrant file on CI

* Install vagrant

* Install vagrant

* Install vagrant

* Install vagrant

* Install vagrant

* Install vagrant

* Test vagrant validate

.gitlab-ci/lint.yml

@@ -6,6 +6,15 @@ yamllint:
     - yamllint --strict .
   except: ['triggers', 'master']
 
+vagrant-validate:
+  extends: .job
+  stage: unit-tests
+  script:
+    - curl -sL https://releases.hashicorp.com/vagrant/2.2.4/vagrant_2.2.4_x86_64.deb -o /tmp/vagrant_2.2.4_x86_64.deb
+    - dpkg -i /tmp/vagrant_2.2.4_x86_64.deb
+    - vagrant validate --ignore-provider
+  except: ['triggers', 'master']
+
 ansible-lint:
   extends: .job
   stage: unit-tests