Home / server / Questions / 960029
Accepted
gertvdijk
Asked: 2019-03-27 04:04:04 +0800 CST

How do I let Ansible show the diff of a newly created file in check mode?

  • 772

Let's say I manage file myfile.conf with Ansible, e.g.:

- template:
    src: "myfile.conf.j2"
    dest: "/etc/myfile.conf"

I can then see the diff in a dry-run, like this:

$ ansible-playbook --check --diff myplaybook.yaml

Cool. But it seems to only display the diff when the file exists on the remote host. If the file is absent, I don't see the output other than task OK.

How do I tell Ansible to show the diff if the file is absent currently?

Perhaps similar to how Git would show a diff in a commit of a newly created file in style like with /dev/null as base in the diff:

--- /dev/null
+++ b/myfile.conf.j2
ansible

2 Answers

  1. Best Answer

    Works for me (ansible 2.7.9):

      - name: Create haproxy.cfg
    template:
      src: templates/haproxy.cfg.j2
      dest: /var/tmp/haproxy-keepalived/haproxy.cfg

ansible-playbook --check --diff haproxy-keepalived.yaml
...
changed: [kmaster2]
--- before
+++ after: /root/.ansible/tmp/ansible-local-31057pak66sgj/tmp_de6cqgb/haproxy.cfg.j2
@@ -0,0 +1,33 @@
+global
+  daemon
+  log 127.0.0.1 local0 debug
...

    Perhaps it is version-dependent or you are hitting max_diff_size (default 104448 bytes).

    • 3

  2. That use case is not really implemented in Ansible but you might be able to get the output you want by adding dummy content to the file if it doesn't exist before creating it, like this:

    ---

- name: check if file exists
  stat:
    path: /etc/myfile.conf
  register: file

- name: add dummy line to file
  lineinfile:
    dest: /etc/myfile.conf
    state: present
    line: "bump"
    create: True
  when: file.stat.exists == False

- template:
    src: "myfile.conf.j2"
    dest: "/etc/myfile.conf"
    • 1