How to create a file locally with ansible templates on the development machine

If you cannot do/allow localhost SSH, you can split the playbook on local actions and remote actions.

The connection: local says to not use SSH for a playbook, as shown here: https://docs.ansible.com/ansible/latest/user_guide/playbooks_delegation.html#local-playbooks

Example:

# myplaybook.yml

- hosts: remote_machines
  tasks:
  - debug: msg="do stuff in the remote machines"

- hosts: 127.0.0.1
  connection: local
  tasks:
  - debug: msg="ran in local ansible machine"

- hosts: remote_machines
  tasks:
  - debug: msg="do more stuff in remote machines"

Ansible has a local_action directive to support these scenarios which avoids the localhost and/or ansible_connection workarounds and is covered in the Delegation docs.

To modify your original example to use local_action:

- name: create some file
    local_action: template src=~/workspace/ansible_templates/somefile_template.j2 dest=/etc/somefile/apps-available/someproject.ini

which looks cleaner.

You can delegate tasks with the param delegate_to to any host you like, for example:

- name: create some file
  template: src=~/workspace/ansible_templates/somefile_template.j2 dest=/etc/somefile/apps-available/someproject.ini
  delegate_to: localhost

See Playbook Delegation in the docs.

If your playbook should in general run locally and no external hosts are involved though, you can simply create a group which contains localhost and then run the playbook against this group. In your inventory:

[local]
localhost   ansible_connection=local

and then in your playbook:

hosts: local