Abort execution of remaining task if certain condition is failed

Question

I want to abort execution of remaining task if certain condition is failed. and display proper error message.

So instead of skipping remaining task I want to show error message and stop execution of ansible playbook.

Lets say I am running below command

$ ansible-playbook playbook.yml -e "param1=value1 param2=value"

My playbook look like this:-

playbook.yml:-

---
    - hosts: local
      user: roop
      gather_facts: no

      vars: {param1: "", param2: ""}

      tasks:

        #check whether param1 defined
        - name: 'Check for valid param1'
          shell: echo {{ param1 }}
          register: isValidParam1
          when: param1 !=""

        #check if param1 is null or invalid  
        - name: 'check if param1 is null or invalid' 
          debug: msg="Please enter correct param1"
          when: param1 == ""

        #check whether param2 defined
        - name: 'Check for valid param2'
          shell: echo {{ param2 }}
          register: isValidParam2
          when: param2 != ""

        #check if param2 is null or invalid  
        - name: 'check if param2 is null or invalid' 
          debug: msg="Please enter correct param2"
          when: param2 == ""  


        #check params is valid and defined
        - name: 'Check for valid params'
          shell: echo "param1={{ param1 }} param2={{ param2 }}
          register: validParams
          when: isValidParam1 is defined and isValidParam2 is defined

        #check if params are invalid then abort below all tasks.  
        - name: 'check if validParams is null or invalid' 
          debug: msg="Please enter correct Params"
          when: validParams is not defined    


         # based on validParams, and different value of param1 more than 
          10 task executing.

As I have mentioned in my last task comment. I am executing more than 10 task based on validParams and param1 different value. What I need here if validParams is undefined then abort all execution and show error messages.

Is there any efficient way to do this . Please suggest me.

Answer 1

You can use assert http://docs.ansible.com/assert_module.html or fail http://docs.ansible.com/fail_module.html

It will go along with something like this

        #check if params are invalid then abort below all tasks.  
        - name: 'check parm is null or invalid' 
          fail: msg="Please enter correct Params"
          when: "param1 is not defined or param2 is not defined " ## whatever condition you want

Answer 2

So in Ansible 2.2+ there is the meta module: http://docs.ansible.com/ansible/latest/meta_module.html

So

meta: end_play

stops the playbook with a non failing status

Answer 3

Ansible >= 2.0 has a block feature that allows you to logically group tasks. This allows you to apply a when to a group of tasks.

The main difference between this and the fail or assert modules is that the task isn't marked as failed; it's just skipped. Whether this is better depends on your use case. For example I have some tasks that write to a log that's later parsed for failures; it's easier to do this if only "real" failure conditions are logged.

Example code:

- block:

    # task 1

    # task 2

    # task 3

  when: "param1 is defined or param2 is defined"

# otherwise output a message
- block:

    debug: msg="Missing params"

  when: "param1 is not defined or param2 is not defined"