Add subcommands parameter for module alternatives. (#4654)

* Add slaves parameter for module alternatives.

* alternatives: Improve documentation abous slaves parameter

* alternatives: Apply suggestions from code review

Co-authored-by: Felix Fontein <felix@fontein.de>

* alternatives: Add schangelog for slaves parameter

* alernatives: Add integration tests

* alternatives: Improv tests

* alternatives: Update tests/integration/targets/alternatives/tasks/slaves.yml

Co-authored-by: Felix Fontein <felix@fontein.de>

* alternatives: Rework logic to support updating priority and subcommands

* alternatives: Use more inclusive naming

* alternatives: Fix linter warnings

* alternatives: Dont fail if link is absent

* alternatives: Update changelog fragment

* alternatives: Add tests for prio change and removing

* alternatives: Apply suggestions from code review

Co-authored-by: Felix Fontein <felix@fontein.de>

* alternatives: Add `state=auto`to reset mode to auto

* alternatives: Fix linter warnings

* alternatives: Fix documentation.

* alternatives: Combine multiple messages.

* alternatives: Set command env for all commands.

* alternatives: Do not update subcommands if parameter is omited

* alternatives: Fix a bug with python 2.7 var scoping

* alternatives: Improce diff before generation

* alternatives: Fix linter warnings

* alternatives: Fix test names

* alternatives: Simplify subcommands handling and improve diffs

* aliases: Only test for subcommand changes if subcommands parameter is set.

* Update plugins/modules/system/alternatives.py

Co-authored-by: Felix Fontein <felix@fontein.de>

* Apply suggestions from code review

Co-authored-by: Felix Fontein <felix@fontein.de>

tests/integration/targets/alternatives/tasks/main.yml

@@ -49,6 +49,9 @@
   # Test that path is checked: alternatives must fail when path is nonexistent
   - import_tasks: path_is_checked.yml
 
+  # Test that subcommands commands work
+  - import_tasks: subcommands.yml
+
   # Test operation of the 'state' parameter
   - block:
     - include_tasks: remove_links.yml

tests/integration/targets/alternatives/tasks/subcommands.yml

@@ -0,0 +1,78 @@
+- name: Try with subcommands
+  alternatives:
+    name: dummymain
+    path: '/usr/bin/dummy1'
+    link: '/usr/bin/dummymain'
+    subcommands:
+      - name: dummysubcmd
+        path: '/usr/bin/dummy2'
+        link: '/usr/bin/dummysubcmd'
+  register: alternative
+
+- name: Check expected command was executed
+  assert:
+    that:
+      - 'alternative is changed'
+
+- name: Execute the current dummymain command
+  command: dummymain
+  register: cmd
+
+- name: Ensure that the expected command was executed
+  assert:
+    that:
+      - cmd.stdout == "dummy1"
+
+- name: Execute the current dummysubcmd command
+  command: dummysubcmd
+  register: cmd
+
+- name: Ensure that the expected command was executed
+  assert:
+    that:
+      - cmd.stdout == "dummy2"
+
+- name: Subcommands are not removed if not specified
+  alternatives:
+    name: dummymain
+    path: '/usr/bin/dummy1'
+    link: '/usr/bin/dummymain'
+  register: alternative
+
+- name: Check expected command was executed
+  assert:
+    that:
+      - 'alternative is not changed'
+
+- name: Execute the current dummysubcmd command
+  command: dummysubcmd
+  register: cmd
+
+- name: Ensure that the expected command was executed
+  assert:
+    that:
+      - cmd.stdout == "dummy2"
+
+- name: Subcommands are removed if set to an empty list
+  alternatives:
+    name: dummymain
+    path: '/usr/bin/dummy1'
+    link: '/usr/bin/dummymain'
+    subcommands: []
+  register: alternative
+
+- name: Check expected command was executed
+  assert:
+    that:
+      - 'alternative is changed'
+
+- name: Execute the current dummysubcmd command
+  command: dummysubcmd
+  register: cmd
+  ignore_errors: True
+
+- name: Ensure that the subcommand is gone
+  assert:
+    that:
+      - cmd.rc == 2
+      - '"No such file" in cmd.msg'

tests/integration/targets/alternatives/tasks/test.yml

@@ -48,6 +48,4 @@
   when: ansible_os_family == 'RedHat' and not with_alternatives and item == 1
 
 - name: check that alternative has been updated
-  command: "grep -Pzq '/bin/dummy{{ item }}\\n' '{{ alternatives_dir }}/dummy'"
-  # priority doesn't seem updated
-  #command: "grep -Pzq '/bin/dummy{{ item }}\\n50' '{{ alternatives_dir }}/dummy'"
+  command: "grep -Pzq '/bin/dummy{{ item }}\\n50' '{{ alternatives_dir }}/dummy'"

tests/integration/targets/alternatives/tasks/tests_set_priority.yml

@@ -21,3 +21,14 @@
 
 - name: check that alternative has been updated
   command: "grep -Pzq '/bin/dummy{{ item }}\\n{{ 60 + item|int }}' '{{ alternatives_dir }}/dummy'"
+
+- name: update dummy priority
+  alternatives:
+    name: dummy
+    path: '/usr/bin/dummy{{ item }}'
+    link: /usr/bin/dummy
+    priority: '{{ 70 + item|int }}'
+  register: alternative
+
+- name: check that alternative priority has been updated
+  command: "grep -Pzq '/bin/dummy{{ item }}\\n{{ 70 + item|int }}' '{{ alternatives_dir }}/dummy'"

tests/integration/targets/alternatives/tasks/tests_state.yml

@@ -49,6 +49,28 @@
       - cmd.stdout == "dummy4"
 
 # Set the currently selected alternative to state = 'present' (was previously
+# selected), and ensure that this results in the group not being set to 'auto'
+# mode, and the alternative is still selected.
+- name: Set current selected dummy to state = present
+  alternatives:
+    name: dummy
+    path: /usr/bin/dummy4
+    link: /usr/bin/dummy
+    state: present
+
+- name: Ensure that the link group is in auto mode
+  shell: 'head -n1 {{ alternatives_dir }}/dummy | grep "^manual$"'
+
+- name: Execute the current dummy command
+  shell: dummy
+  register: cmd
+
+- name: Ensure that the expected command was executed
+  assert:
+    that:
+      - cmd.stdout == "dummy4"
+
+# Set the currently selected alternative to state = 'auto' (was previously
 # selected), and ensure that this results in the group being set to 'auto'
 # mode, and the highest priority alternative is selected.
 - name: Set current selected dummy to state = present
@@ -56,7 +78,7 @@
     name: dummy
     path: /usr/bin/dummy4
     link: /usr/bin/dummy
-    state: present
+    state: auto
 
 - name: Ensure that the link group is in auto mode
   shell: 'head -n1 {{ alternatives_dir }}/dummy | grep "^auto$"'
@@ -69,3 +91,25 @@
   assert:
     that:
       - cmd.stdout == "dummy2"
+
+# Remove an alternative with state = 'absent' and make sure that
+# this change results in the alternative being removed.
+- name: Remove best dummy alternative with state = absent
+  alternatives:
+    name: dummy
+    path: /usr/bin/dummy2
+    state: absent
+
+- name: Ensure that the link group is in auto mode
+  shell: 'grep "/usr/bin/dummy2" {{ alternatives_dir }}/dummy'
+  register: cmd
+  failed_when: cmd.rc == 0
+
+- name: Execute the current dummy command
+  shell: dummy
+  register: cmd
+
+- name: Ensure that the expected command was executed
+  assert:
+    that:
+      - cmd.stdout == "dummy1"