How to generate terraform execution plan using ansible role? - ansible

Question

Terraform module provided by ansible works well for creating aws resources with S3 backend config for statefile.
but not able to get the terraform plan output using this module.
We want the output should list something like:
Plan: 1 to add, 0 to change, 0 to destroy.
and give details of the resources to be created/destroyed/changed
Have tried below task in ansible, but not able to generate output as expected.
below is ansible task for creating plan:
- name: "create file"
shell: "touch {{playbook_dir}}/tfplan && ls -larth ../terraform/{{role_name}} "
- name: "Run terraform project with plan file"
terraform:
state: planned
backend_config:
bucket: "{{bootstrap_prefix}}-{{aws_account_type}}-{{caller_facts.account}}"
region: "{{ bootstrap_aws_region }}"
kms_key_id: "{{ kms_id.stdout }}"
encrypt: true
workspace_key_prefix: "{{ app_parent }}-{{ app_name }}"
key: "terraform.tfstate"
force_init: true
project_path: "../terraform/{{role_name}}"
plan_file: "{{playbook_dir}}/tfplan"
variables:
app_name: "{{ app_name }}"
workspace: "{{ app_env }}"
Output of above ansible task:
ok: [localhost] => {
"changed": false,
"command": "/usr/local/bin/terraform -lock=true /root/project/ansible/tfplan",
"invocation": {
"module_args": {
"backend_config": {
"bucket": "XXXXXXXX2440728499",
"encrypt": true,
"key": "terraform.tfstate",
"kms_key_id": "XXXXXXXX",
"region": "XXXXXXXX",
"workspace_key_prefix": "XXXXXX"
},
"binary_path": null,
"force_init": true,
"lock": true,
"lock_timeout": null,
"plan_file": "/root/project/ansible/tfplan",
"project_path": "../terraform/applications",
"purge_workspace": false,
"state": "planned",
"state_file": null,
"targets": [],
"variables": {
"app_name": "application"
},
"variables_file": null,
"workspace": "uat"
}
},
"outputs": {},
"state": "planned",
"stderr": "",
"stderr_lines": [],
"stdout": "",
"stdout_lines": [],
"workspace": "uat"
}
It works fine with state: present (terraform apply) , but want it to work with state:planned (terraform plan)

Answer 1

In current ansible documentation: To just run a terraform plan, use check mode.
In addition, you should add to terraform module parameters:
- name: "Run terraform project with plan file"
terraform:
state: planned
check_mode: true