ansible loop fail

Problem: loops were failing when trying to pass a variable with something like "foo,bar" in it. This is just a string with a comma in it.

ansible error: Invalid data passed to 'loop', it requires a list

Solution: enscapsulate with square brackets [ ] and quotes around individual elements.

example:

["foo","bar"]

Example Play

 - name: example play showing common loop/list error
 hosts: localhost
 gather_facts: false
 tasks:
   - name: set var1
     set_fact:
     var1: "foo,bar"
    
   - name: set var2
     set_fact:
     var2: ["foo","bar"]
   
   - name: output var1 type
     debug:
     msg: "{{ var1 | type_debug }}"
   
   - name: output var2 type
     debug:
     msg: "{{ var2 | type_debug }}"
   
   - name: try to loop var2
     debug:
     msg: "{{ item }}"
     loop: "{{ var2 }}"
   
   - name: try to loop var1
     debug:
     msg: "{{ item }}"
     loop: "{{ var1 }}"

$ ansible-playbook example_list.yml

 PLAY [localhost] 
 *******************************************************************************************************      
 
 TASK [set var1] 
 *******************************************************************************************************
 ok: [localhost]
 
 TASK [set var2] 
 ********************************************************************************************************
 ok: [localhost]
 
 TASK [output var1 type] 
 ************************************************************************************************
 ok: [localhost] => {
 "msg": "AnsibleUnicode"
 } 
 
 TASK [output var2 type] 
 ************************************************************************************************
 ok: [localhost] => {
 "msg": "list"
 } 
 
 TASK [try to loop var2] 
 ************************************************************************************************
 ok: [localhost] => (item=foo) => {
 "msg": "foo"
 }
 ok: [localhost] => (item=bar) => {
 "msg": "bar"
 } 
 
 TASK [try to loop var1] 
 ************************************************************************************************
 fatal: [localhost]: FAILED! => {"msg": "Invalid data passed to 'loop', it requires a list, got this 
 instead: foo,bar. Hint: If you passed a list/dict of just one element, try adding wantlist=True to your 
 lookup invocation or use q/query instead of lookup."}
 
 PLAY RECAP 
 *************************************************************************************************************
 localhost                  : ok=5    changed=0    unreachable=0    failed=1    skipped=0    rescued=0    
 ignored=0