ansible variable as environment variable

I try this - name: Install required packages shell: "apt-get instal linux-headers-{{ ansible_kernel }}" However getting this instead {"msg": "The task includes an option with an undefined variable. The error was: 'ansible_kernel' is undefined\ I can can see this variable via ansible -i myinventoryfile myhost -m setup | grep kernel and also ansible -i myinventoryfile myhost -m shell -a "uname -r" how can I get this working ?