refactor: support Ansible 2.19

Ansible 2.19 introduces some big changes
https://docs.ansible.com/ansible/devel/porting_guides/porting_guide_core_2.19.html

One big change is that data structures are no longer mutable by the use of python
methods such as `__setitem__`, `setdefault`, `update`, etc.  in Jinja constructs.
Instead, items must use filters or other Jinja operations.

One common idiom is to mutate each element in a list.  Since we cannot do this
"in-place" anymore, a common way to do this is:

```yaml
- name: Construct a new list from an existing list and mutate each element
  set_fact:
    __new_list: "{{ __new_list | d([]) + [mutated_item] }}"
  loop: "{{ old_list }}"
  mutated_item: "{{ some value based on item from old list }}"

- name: Reset original old list
  set_fact:
    old_list: "{{ __new_list }}"
```

Similarly with `dict` items:

```yaml
- name: Construct a new dict from an existing dict and mutate each element
  set_fact:
    __new_dict: "{{ __new_dict | d({}) | combine(mutated_item) }}"
  loop: "{{ old_dict | dict2items }}"
  mutated_item: "{{ {item.key: mutation of item.value} }}"

- name: Reset original old dict
  set_fact:
    old_dict: "{{ __new_dict }}"
```

Another big change is that a boolean expression in a `when` or similar construct
must be converted to a boolean - we cannot rely on the implicit evaluation in
a boolean context.  For example, if `var` is some iterable, like a `dict`, `list`,
or `string`, you used to be able to evaluate an empty value in a boolean context:

```yaml
when: var  # do this only if var is not empty
```

You now have to explicitly test for empty using `length`:

```yaml
when: var | length > 0  # do this only if var is not empty
```

Signed-off-by: Rich Megginson <rmeggins@redhat.com>

Author: richm

tasks/main.yml

@@ -120,63 +120,87 @@
     path: "{{ __kernel_settings_profile_filename }}"
   register: __kernel_settings_profile_contents
 
-- name: Apply kernel settings
-  template:
-    src: "{{ __kernel_settings_profile_src }}.j2"
-    dest: "{{ __kernel_settings_profile_filename }}"
-    mode: "0644"
-  vars:
-    __sysctl_old: "{{ __kernel_settings_profile_contents.data.get('sysctl', {})
+- name: Initialize new sysctl
+  set_fact:
+    __kernel_settings_new_sysctl: "{{
+      __kernel_settings_profile_contents.data.get('sysctl', {})
       if not kernel_settings_purge
       and kernel_settings_sysctl != __kernel_settings_state_empty
       and not __kernel_settings_previous_replaced in kernel_settings_sysctl
       else {} }}"
-    __sysfs_old: "{{ __kernel_settings_profile_contents.data.get('sysfs', {})
+
+- name: Set new sysctl
+  set_fact:
+    __kernel_settings_new_sysctl: "{{ __kernel_settings_new_sysctl | combine(__new_item) }}"
+  loop: "{{ [] if kernel_settings_sysctl == __kernel_settings_state_empty
+    else kernel_settings_sysctl | rejectattr('previous', 'defined') | list }}"
+  vars:
+    __new_item: "{{ {item.name: __new_value} }}"
+    __new_value: "{{ __kernel_settings_state_absent
+      if item.state | d('present') == 'absent'
+      else item.value | d(__kernel_settings_state_absent) }}"
+
+- name: Initialize new sysfs
+  set_fact:
+    __kernel_settings_new_sysfs: "{{
+      __kernel_settings_profile_contents.data.get('sysfs', {})
       if not kernel_settings_purge
       and kernel_settings_sysfs != __kernel_settings_state_empty
       and not __kernel_settings_previous_replaced in kernel_settings_sysfs
       else {} }}"
+
+- name: Set new sysfs
+  set_fact:
+    __kernel_settings_new_sysfs: "{{ __kernel_settings_new_sysfs | combine(__new_item) }}"
+  loop: "{{ [] if kernel_settings_sysfs == __kernel_settings_state_empty
+    else kernel_settings_sysfs | rejectattr('previous', 'defined') | list }}"
+  vars:
+    __new_item: "{{ {item.name: __new_value} }}"
+    __new_value: "{{ __kernel_settings_state_absent
+      if item.state | d('present') == 'absent'
+      else item.value | d(__kernel_settings_state_absent) }}"
+
+- name: Apply kernel settings
+  template:
+    src: "{{ __kernel_settings_profile_src }}.j2"
+    dest: "{{ __kernel_settings_profile_filename }}"
+    mode: "0644"
+  vars:
+    # we don't have a way to compare an item to a dict - eq not available in el7
+    # so assume if the value is a dict, it is the {"state": "absent"} dict
+    # because "real" values should be scalars like strings, int, bool
+    __sysctl_has_values: "{{ __kernel_settings_new_sysctl | dict2items | rejectattr('value', 'mapping') | list | length > 0 }}"
+    __sysfs_has_values: "{{ __kernel_settings_new_sysfs | dict2items | rejectattr('value', 'mapping') | list | length > 0 }}"
     __systemd_old: "{{
-      __kernel_settings_profile_contents.data.get('systemd', {}).get('cpu_affinity')
+      __kernel_settings_profile_contents.data.get('systemd', {}).get('cpu_affinity', '')
       if not kernel_settings_purge
       and kernel_settings_systemd_cpu_affinity != __kernel_settings_state_absent
-      else none }}"
+      else '' }}"
+    __systemd_new: "{{ kernel_settings_systemd_cpu_affinity
+      if kernel_settings_systemd_cpu_affinity is not none and
+      kernel_settings_systemd_cpu_affinity != __kernel_settings_state_absent and
+      kernel_settings_systemd_cpu_affinity | length > 0
+      else __systemd_old }}"
     __trans_huge_old: "{{
-      __kernel_settings_profile_contents.data.get('vm', {}).get('transparent_hugepages')
+      __kernel_settings_profile_contents.data.get('vm', {}).get('transparent_hugepages', '')
       if not kernel_settings_purge
       and kernel_settings_transparent_hugepages != __kernel_settings_state_absent
-      else none }}"
+      else '' }}"
+    __trans_huge_new: "{{ kernel_settings_transparent_hugepages
+      if kernel_settings_transparent_hugepages is not none and
+      kernel_settings_transparent_hugepages != __kernel_settings_state_absent and
+      kernel_settings_transparent_hugepages | length > 0
+      else __trans_huge_old }}"
     __trans_defrag_old: "{{
-      __kernel_settings_profile_contents.data.get('vm', {}).get('transparent_hugepage.defrag')
+      __kernel_settings_profile_contents.data.get('vm', {}).get('transparent_hugepage.defrag', '')
       if not kernel_settings_purge
       and kernel_settings_transparent_hugepages_defrag != __kernel_settings_state_absent
-      else none }}"
-    __sections:
-      - name: sysctl
-        new: "{{ kernel_settings_sysctl | difference([__kernel_settings_previous_replaced]) | list
-          if kernel_settings_sysctl != __kernel_settings_state_empty
-          else [] }}"
-        old: "{{ __sysctl_old }}"
-      - name: sysfs
-        new: "{{ kernel_settings_sysfs | difference([__kernel_settings_previous_replaced]) | list
-          if kernel_settings_sysfs != __kernel_settings_state_empty
-          else [] }}"
-        old: "{{ __sysfs_old }}"
-      - name: systemd
-        new:
-          - name: cpu_affinity
-            value: "{{ kernel_settings_systemd_cpu_affinity }}"
-        old:
-          cpu_affinity: "{{ __systemd_old }}"
-      - name: vm
-        new:
-          - name: transparent_hugepages
-            value: "{{ kernel_settings_transparent_hugepages }}"
-          - name: transparent_hugepage.defrag
-            value: "{{ kernel_settings_transparent_hugepages_defrag }}"
-        old:
-          transparent_hugepages: "{{ __trans_huge_old }}"
-          transparent_hugepage.defrag: "{{ __trans_defrag_old }}"
+      else '' }}"
+    __trans_defrag_new: "{{ kernel_settings_transparent_hugepages_defrag
+      if kernel_settings_transparent_hugepages_defrag is not none and
+      kernel_settings_transparent_hugepages_defrag != __kernel_settings_state_absent and
+      kernel_settings_transparent_hugepages_defrag | length > 0
+      else __trans_defrag_old }}"
   register: __kernel_settings_register_apply
 
 # this will also apply the kernel_settings profile, so we

templates/kernel_settings.j2

@@ -1,33 +1,31 @@
 {{ ansible_managed | comment }}
 {{ "system_role:kernel_settings" | comment(prefix="", postfix="") }}
-[main]
-summary = kernel settings
-{% set __settings = {} %}
-{% for section in __sections %}
-{%   set section_name = section["name"] %}
-{%   for item in section["new"] %}
-{%     if item.state | d() == "absent" %}
-{%       set _ = __settings.setdefault(section_name, {}).__setitem__(item.name, __kernel_settings_state_absent) %}
-{%     elif item.value != none and item.value != "" %}
-{%       set _ = __settings.setdefault(section_name, {}).__setitem__(item.name, item.value) %}
-{%     endif %}
-{%   endfor %}
-{%   for key, value in section["old"].items() %}
-{%     if not __settings.get(section_name, {}).__contains__(key) and value != none and value != "" %}
-{%       set _ = __settings.setdefault(section_name, {}).__setitem__(key, value) %}
-{%     endif %}
-{%   endfor %}
-{% endfor %}
-{% set seen_sections = {} %}
-{% for section_name in __settings.keys() | sort %}
-{%   set section = __settings[section_name] %}
-{%   for key in section.keys() | sort %}
-{%     if section[key] != __kernel_settings_state_absent %}
-{%       if not seen_sections.__contains__(section_name) %}
-{%         set _ = seen_sections.__setitem__(section_name, true) %}
+{% macro write_section(section_name, settings) %}
 [{{ section_name }}]
-{%       endif %}
-{{ key }} = {{ section[key] }}
+{%   for key, val in settings.items() %}
+{%     if val != {"state": "absent"} %}
+{{ key }} = {{ val }}
 {%     endif %}
 {%   endfor %}
-{% endfor %}
+{% endmacro %}
+[main]
+summary = kernel settings
+{% if __sysctl_has_values %}
+{{   write_section("sysctl", __kernel_settings_new_sysctl) -}}
+{% endif %}
+{% if __sysfs_has_values %}
+{{   write_section("sysfs", __kernel_settings_new_sysfs) -}}
+{% endif %}
+{% if __systemd_new | length > 0 %}
+[systemd]
+cpu_affinity = {{ __systemd_new }}
+{% endif %}
+{% if __trans_huge_new | length > 0 or __trans_defrag_new | length > 0 %}
+[vm]
+{%   if __trans_huge_new | length > 0 %}
+transparent_hugepages = {{ __trans_huge_new }}
+{%   endif %}
+{%   if __trans_defrag_new | length > 0 %}
+transparent_hugepage.defrag = {{ __trans_defrag_new }}
+{%   endif %}
+{% endif %}

tests/tasks/assert_kernel_settings_conf_files.yml

@@ -80,14 +80,16 @@
   ignore_errors: true
   register: __kernel_settings_register_verify_bl_cmdline
   when:
-    - __kernel_settings_blcmdline_value | d()
+    - __kernel_settings_blcmdline_value | d() is not none
+    - __kernel_settings_blcmdline_value | d("") | length > 0
   changed_when: false
 
 - name: Verify bootloader settings value
   set_fact:
     __kernel_settings_success: false
   when:
-    - __kernel_settings_blcmdline_value | d()
+    - __kernel_settings_blcmdline_value | d() is not none
+    - __kernel_settings_blcmdline_value | d("") | length > 0
     - __kernel_settings_register_verify_bl_cmdline is defined
     - __kernel_settings_register_verify_bl_cmdline.stdout is defined
     - __kernel_settings_register_verify_bl_cmdline is failed or

tests/tasks/check_header.yml

@@ -9,8 +9,8 @@
 - name: Check for presence of ansible managed header, fingerprint
   assert:
     that:
-      - ansible_managed in content
+      - __ansible_managed in content
       - __fingerprint in content
   vars:
     content: "{{ (__file_content | d(__content)).content | b64decode }}"
-    ansible_managed: "{{ lookup('template', 'get_ansible_managed.j2') }}"
+    __ansible_managed: "{{ lookup('template', 'get_ansible_managed.j2') }}"

tests/vars/vars_simple_settings.yml

@@ -53,7 +53,8 @@ __kernel_settings_profile_file: |
   /sys/kernel/debug/x86/ibrs_enabled = 0
   /sys/kernel/debug/x86/pti_enabled = 0
   /sys/kernel/debug/x86/retp_enabled = 0
-  {% if __kernel_settings_blcmdline_value | d() %}
+  {% if __kernel_settings_blcmdline_value | d() is not none and
+     __kernel_settings_blcmdline_value | d("") | length > 0 %}
   [bootloader]
   cmdline = {{ __kernel_settings_blcmdline_value }}
   {% endif %}