> podman run --name debian-trixie -it --rm debian:trixie
root@6e69c6fab585:/# apt update
Get:1 http://deb.debian.org/debian trixie InRelease [138 kB]
Get:2 http://deb.debian.org/debian trixie-updates InRelease [47.1 kB]
Get:3 http://deb.debian.org/debian-security trixie-security InRelease [43.4 kB]
Get:4 http://deb.debian.org/debian trixie/main amd64 Packages [9668 kB]
Get:5 http://deb.debian.org/debian trixie-updates/main amd64 Packages [2432 B]
Get:6 http://deb.debian.org/debian-security trixie-security/main amd64 Packages [8780 B]
Fetched 9907 kB in 1s (10.3 MB/s)
All packages are up to date.
root@6e69c6fab585:/# apt install ansible
Installing:
  ansible
...
Setting up ansible (12.0.0~a6+dfsg-1) ...
Processing triggers for libc-bin (2.41-12) ...
Processing triggers for ca-certificates (20250419) ...
Updating certificates in /etc/ssl/certs...
0 added, 0 removed; done.
Running hooks in /etc/ca-certificates/update.d...
done.
root@6e69c6fab585:/# cd $(mktemp -d)
root@6e69c6fab585:/tmp/tmp.i1gsojt4Qs# cat >playbook.yaml <<EOF
> - name: Sample playbook
  hosts: localhost
  tasks:
    - name: Debug print success
      ansible.builtin.debug:
        msg: "{{ template_data }}"
      vars:
        template_data: "{{ lookup('template', 'template.txt') }}"
        template_opts: "{{ sample_var['sample_key'] | default('sample_default') }}"
        sample_var:
          sample_key: "sample_value"

    - name: Debug print failure
      ansible.builtin.debug:
        msg: "{{ template_data }}"
      vars:
        template_data: "{{ lookup('template', 'template.txt') }}"
        template_opts: "{{ sample_var['sample_key2'] | default('sample_default') }}"
        sample_var:
          sample_key: "sample_value"
> EOF
root@6e69c6fab585:/tmp/tmp.i1gsojt4Qs# cat >template.txt <<EOF
> # Sample template
{{ template_opts }}
> EOF
root@6e69c6fab585:/tmp/tmp.i1gsojt4Qs# ansible-playbook playbook.yaml
[WARNING]: No inventory was parsed, only implicit localhost is available
[WARNING]: provided hosts list is empty, only localhost is available. Note that the implicit localhost does not match 'all'

PLAY [Sample playbook] ***********************************************************************************************************************************************************************************

TASK [Gathering Facts] ***********************************************************************************************************************************************************************************
ok: [localhost]

TASK [Debug print success] *******************************************************************************************************************************************************************************
ok: [localhost] => {
    "msg": "# Sample template\nsample_value\n"
}

TASK [Debug print failure] *******************************************************************************************************************************************************************************
[ERROR]: Task failed: Finalization of task args for 'ansible.builtin.debug' failed: Error while resolving value for 'msg': The lookup plugin 'template' failed: object of type 'dict' has no attribute 'sample_key2'

Task failed.
Origin: /tmp/tmp.i1gsojt4Qs/playbook.yaml:13:7

11           sample_key: "sample_value"
12
13     - name: Debug print failure
         ^ column 7

<<< caused by >>>

Finalization of task args for 'ansible.builtin.debug' failed.
Origin: /tmp/tmp.i1gsojt4Qs/playbook.yaml:14:7

12
13     - name: Debug print failure
14       ansible.builtin.debug:
         ^ column 7

<<< caused by >>>

Error while resolving value for 'msg'.
Origin: /tmp/tmp.i1gsojt4Qs/playbook.yaml:15:14

13     - name: Debug print failure
14       ansible.builtin.debug:
15         msg: "{{ template_data }}"
                ^ column 14

<<< caused by >>>

The lookup plugin 'template' failed.
Origin: /tmp/tmp.i1gsojt4Qs/playbook.yaml:17:24

15         msg: "{{ template_data }}"
16       vars:
17         template_data: "{{ lookup('template', 'template.txt') }}"
                          ^ column 24

<<< caused by >>>

object of type 'dict' has no attribute 'sample_key2'
Origin: /tmp/tmp.i1gsojt4Qs/playbook.yaml:18:24

16       vars:
17         template_data: "{{ lookup('template', 'template.txt') }}"
18         template_opts: "{{ sample_var['sample_key2'] | default('sample_default') }}"
                          ^ column 24

fatal: [localhost]: FAILED! => {"msg": "Task failed: Finalization of task args for 'ansible.builtin.debug' failed: Error while resolving value for 'msg': The lookup plugin 'template' failed: object of type 'dict' has no attribute 'sample_key2'"}

PLAY RECAP ***********************************************************************************************************************************************************************************************
localhost                  : ok=2    changed=0    unreachable=0    failed=1    skipped=0    rescued=0    ignored=0