ansible loop over list and dictionary at the same time - loops

Question

I am writing a playbook that ensure nodes appear in /etc/fstab.
I am using loops to prevent code duplication.
The logic is first to check if the line appears using grep (with perl regex because it is a multi line) and store the results in a register.
Then I want to add only the lines that are not in fstab file. To achieve that I need to loop over list (the register with the grep return codes) and a dictionary (that contains the fstab entries).
I am having errors with the parallel loop. I tried to follow these steps.
One or more undefined variables: 'str object' has no attribute 'item'
tasks/fstab.yaml:
---
- name: Make dirs
sudo: yes
file: path={{ item.value }} state=directory
with_dict:
"{{ fstab.paths }}"
- name: Check whether declared in fstab
sudo: no
command: grep -Pzq '{{ item.value }}' /etc/fstab
register: is_declared
with_dict:
"{{ fstab.regexs }}"
- name: Add the missing entries
sudo: yes
lineinfile: dest=/etc/fstab line="{{ item.1.item.value }}"
when: item.0.rc == 1
with_together:
- "{{ is_declared.results }}"
- "{{ fstab.entries }}"
vars/main.yml:
---
fstab:
paths:
a: "/mnt/a"
b: "/mnt/b"
regexs:
a: '\n# \(a\)\nfoo1'
b: '\n# \(b\)\nfoo2'
entries:
a: "\n# (a)\nfoo1"
b: "\n# (b)\nfoo2"
I am not using template on purpose (I want to add entries to existing files and not to over write them).
UPDATE: I see ansible has module "mount" which deals with fstab. However I am still looking for a solution to this issue because I might be needed it again later on.

Answer 1

I have a couple ideas as to why your original approach was failing, but let's scratch that for a moment. It looks like you're overcomplicating things- why not use a complex list var to tie it all together, and use the regexp arg to the lineinfile module instead of a separate regex task? (though your sample data should work fine even without the regexp param) Something like:
---
- name: Make dirs
sudo: yes
file: path={{ item.path }} state=directory
with_items: fstab
- name: Add the missing entries
sudo: yes
lineinfile: dest=/etc/fstab line={{ item.entry }} regexp={{ item.regex }}
with_items: fstab
fstab:
- path: /mnt/a
regex: '\n# \(a\)\nfoo1'
entry: "\n# (a)\nfoo1"
- path: /mnt/b
regex: '\n# \(b\)\nfoo2'
entry: '\n# (b)\nfoo2'