Updated Openstack to terraform 0.12 (#5062)

* update openstack to terraform 0.12(.5)

* replace cluter.tf with cluster.tfvars

* update README.md to terraform 0.12

* update Openstack CI tests to use terraform 0.12

* specify terraform version in openstack README

* gitlab CI to copy cluster.tfvars in case of openstack provider

* The terraform/openstack dynamic inventory can read
tfstate v4 (generated by terraform 0.12) and convert them internally
ro v3 (as generated by terraform 0.11.x).

Additionally the script has been updated to Python 3.

.gitlab-ci/terraform.yml

@@ -9,7 +9,8 @@
     # Set Ansible config
     - cp ansible.cfg ~/.ansible.cfg
     # Prepare inventory
-    - cp contrib/terraform/$PROVIDER/sample-inventory/cluster.tf .
+    - if [ "$PROVIDER" == "openstack" ]; then VARIABLEFILE="cluster.tfvars"; else VARIABLEFILE="cluster.tf"; fi
+    - cp contrib/terraform/$PROVIDER/sample-inventory/$VARIABLEFILE .
     - ln -s contrib/terraform/$PROVIDER/hosts
     - terraform init contrib/terraform/$PROVIDER
     # Copy SSH keypair
@@ -23,7 +24,8 @@
   stage: unit-tests
   only: ['master', /^pr-.*$/]
   script:
-    - terraform validate -var-file=cluster.tf contrib/terraform/$PROVIDER
+    - if [ "$PROVIDER" == "openstack" ]; then VARIABLEFILE="cluster.tfvars"; else VARIABLEFILE="cluster.tf"; fi
+    - terraform validate -var-file=$VARIABLEFILE contrib/terraform/$PROVIDER
     - terraform fmt -check -diff contrib/terraform/$PROVIDER
 
 .terraform_apply:
@@ -46,7 +48,7 @@
 tf-validate-openstack:
   extends: .terraform_validate
   variables:
-    TF_VERSION: 0.11.11
+    TF_VERSION: 0.12.6
     PROVIDER: openstack
     CLUSTER: $CI_COMMIT_REF_NAME
 
@@ -108,7 +110,7 @@ tf-ovh_ubuntu18-calico:
   when: on_success
   variables:
     <<: *ovh_variables
-    TF_VERSION: 0.11.11
+    TF_VERSION: 0.12.6
     PROVIDER: openstack
     CLUSTER: $CI_COMMIT_REF_NAME
     ANSIBLE_TIMEOUT: "60"
@@ -136,7 +138,7 @@ tf-ovh_coreos-calico:
   when: on_success
   variables:
     <<: *ovh_variables
-    TF_VERSION: 0.11.11
+    TF_VERSION: 0.12.6
     PROVIDER: openstack
     CLUSTER: $CI_COMMIT_REF_NAME
     ANSIBLE_TIMEOUT: "60"