refactor: Use vars/RedHat_N.yml symlink for CentOS, Rocky, Alma where…

…ver possible

We have a lot of requests to support Rocky and Alma in various system roles. The
first part of adding support is adding `vars/` files for these platforms. In
almost every case, for a given major version N, the vars file RedHat_N.yml can
be used for CentOS, Rocky, and Alma.  Rather than making a copy of the
RedHat_N.yml file, just use a symlink to reduce size and maintenance burden, and
standardize this across all system roles for consistency.

NOTE: OracleLinux is not a strict clone, so we are not going to do this for
OracleLinux at this time.  Support for OracleLinux will need to be done in
separate PRs. For more information, see
#130

Note that there may be more work to be done to the role to fully support Rocky
and Alma.  Many roles have conditionals like this:

```yaml
some_var: "{{ 'some value' if ansible_distribution in ['CentOS', 'RedHat'] else 'other value' }}"
another_var: "{{ 'some value' if ansible_distribution in ['CentOS', 'Fedora', 'RedHat'] else 'other value' }}"

...

- name: Do something
  when: ansible_distribution in ['CentOS', 'RedHat']
  ...
- name: Do something else
  when: ansible_distribution in ['CentOS', 'Fedora', 'RedHat']
  ...
```

Adding Rocky and AlmaLinux to these conditionals will have to be done
separately. In order to simplify the task, some new variables are being
introduced:

```yaml
__$rolename_rh_distros:
  - AlmaLinux
  - CentOS
  - RedHat
  - Rocky

__$rolename_rh_distros_fedora: "{{ __$rolename_rh_distros + ['Fedora'] }}"

__$rolename_is_redhat_distro: "{{ ansible_distribution in __$rolename_rh_distros }}"
__$rolename_is_redhat_distro_fedora: "{{ ansible_distribution in __$rolename_rh_distros_fedora }}"
```

Then the conditionals can be rewritten as:

```yaml
some_var: "{{ 'some value' if __$rolename_is_redhat_distro else 'other value' }}"
another_var: "{{ 'some value' if __$rolename_is_redhat_distro_fedora else 'other value' }}"

...

- name: Do something
  when: __$rolename_is_redhat_distro | bool
  ...
- name: Do something else
  when: __$rolename_is_redhat_distro_fedora | bool
  ...
```

For tests - tests that use such conditionals will need to use `vars_files` or
`include_vars` to load the variables that are defined in
`tests/vars/redhat_clone_vars.yml`:

```yaml
vars_files:
  - vars/redhat_clone_vars.yml
```

We don't currently have CI testing for Rocky or Alma, so someone wanting to run
tests on those platforms would need to change the test code to use these.

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

tests/vars/redhat_clone_vars.yml

@@ -0,0 +1,15 @@
+# vars for handling conditionals for RedHat and clones
+---
+# Ansible distribution identifiers that the role treats like RHEL
+__cockpit_rh_distros:
+  - AlmaLinux
+  - CentOS
+  - RedHat
+  - Rocky
+
+# Same as above but includes Fedora
+__cockpit_rh_distros_fedora: "{{ __cockpit_rh_distros + ['Fedora'] }}"
+# Use this in conditionals to check if distro is Red Hat or clone
+__cockpit_is_rh_distro: "{{ ansible_distribution in __cockpit_rh_distros }}"
+# Use this in conditionals to check if distro is Red Hat or clone, or Fedora
+__cockpit_is_rh_distro_fedora: "{{ ansible_distribution in __cockpit_rh_distros_fedora }}"

vars/AlmaLinux-10.yml

@@ -0,0 +1 @@
+RedHat-10.yml

vars/AlmaLinux-7.yml

@@ -0,0 +1 @@
+RedHat-7.yml

vars/AlmaLinux-8.yml

@@ -0,0 +1 @@
+RedHat-8.yml

vars/AlmaLinux-9.yml

@@ -0,0 +1 @@
+RedHat-9.yml

vars/CentOS-10.yml

@@ -0,0 +1 @@
+RedHat-10.yml

vars/CentOS-8.yml

@@ -0,0 +1 @@
+RedHat-8.yml

vars/CentOS-9.yml

@@ -0,0 +1 @@
+RedHat-9.yml

vars/Rocky-10.yml

@@ -0,0 +1 @@
+RedHat-10.yml

vars/Rocky-7.yml

@@ -0,0 +1 @@
+RedHat-7.yml

vars/Rocky-8.yml

@@ -0,0 +1 @@
+RedHat-8.yml

vars/Rocky-9.yml

@@ -0,0 +1 @@
+RedHat-9.yml

vars/main.yml

@@ -22,3 +22,20 @@ __cockpit_required_facts:
 # the 'gather_subset' parameter of the 'setup' module
 __cockpit_required_facts_subsets: "{{ ['!all', '!min'] +
   __cockpit_required_facts }}"
+
+# BEGIN redhat distros variables
+# Ansible distribution identifiers that the role treats like RHEL
+__cockpit_rh_distros:
+  - AlmaLinux
+  - CentOS
+  - RedHat
+  - Rocky
+
+# Same as above but includes Fedora
+__cockpit_rh_distros_fedora: "{{ __cockpit_rh_distros + ['Fedora'] }}"
+# Use this in conditionals to check if distro is Red Hat or clone
+__cockpit_is_rh_distro: "{{ ansible_distribution in __cockpit_rh_distros }}"
+
+# Use this in conditionals to check if distro is Red Hat or clone, or Fedora
+__cockpit_is_rh_distro_fedora: "{{ ansible_distribution in __cockpit_rh_distros_fedora }}"
+# END redhat distros variables