[AGENTONB-2711] Allow Agent downgrades on Windows

README.md

@@ -89,6 +89,8 @@ These variables provide additional configuration during the installation of the
 | `datadog_windows_ddagentuser_name`          | The name of Windows user to create/use, in the format `<domain>\<user>` (Windows only).|
 | `datadog_windows_ddagentuser_password`      | The password used to create the user and/or register the service (Windows only).|
 | `datadog_apply_windows_614_fix`             | Whether or not to download and apply file referenced by `datadog_windows_614_fix_script_url` (Windows only). See https://dtdg.co/win-614-fix for more details. You can set this to `false` assuming your hosts aren't running Datadog Agent 6.14.\*.|
+| `datadog_windows_skip_install`              | Set to `true` to force the role to skip Windows Agent installation even if the role detects that installation is required (Windows only).|
+| `datadog_windows_force_reinstall`           | Set to `true` to force the role to reinstall the Windows Agent regardless of the automatic feature detection logic (Windows only).|
 | `datadog_macos_user`                        | The name of the user to run Agent under. The user has to exist, it won't be created automatically. Defaults to `ansible_user` (macOS only).|
 | `datadog_macos_download_url`                | Override the URL to download the DMG installer from (macOS only).|
 | `datadog_apm_instrumentation_enabled`       | Configure APM instrumentation. Possible values are: <br/> - `host`: Both the Agent and your services are running on a host. <br/> - `docker`: The Agent and your services are running in separate Docker containers on the same host.<br/>- `all`: Supports all the previous scenarios for `host` and `docker` at the same time.|

defaults/main.yml

@@ -161,6 +161,14 @@ datadog_windows_614_fix_script_url: "https://s3.amazonaws.com/ddagent-windows-st
 # whether or not to download and apply the above fix
 datadog_apply_windows_614_fix: true
 
+# Force the role to skip reinstall steps on Windows, even if the Agent
+# isn't detected yet.
+datadog_windows_skip_install: false
+
+# Force the role to reinstall the Agent on Windows regardless of the
+# automatic feature checks. This can be used to downgrade the Agent on Windows.
+datadog_windows_force_reinstall: false
+
 # Override to change the name of the windows user to create
 datadog_windows_ddagentuser_name: ""
 # Override to change the password of the created windows user.

tasks/parse-version-windows.yml

@@ -19,3 +19,20 @@
   failed_when: false
   check_mode: false
   when: ansible_facts.os_family == "Windows"
+
+- name: Parse installed Windows Agent version into components
+  ansible.builtin.set_fact:
+    agent_datadog_installed_version: "{{ agent_datadog_version_check_win.stdout | trim |
+      regex_search(installed_agent_regexp, '\\g<major>', '\\g<minor>', '\\g<bugfix>') }}"
+  vars:
+    installed_agent_regexp: (?P<major>[0-9]+)\.(?P<minor>[0-9]+)\.(?P<bugfix>[0-9]+)
+  when: >-
+    ansible_facts.os_family == "Windows" and
+    agent_datadog_version_check_win.stdout | trim | length > 0
+
+- name: Set installed version component vars
+  ansible.builtin.set_fact:
+    agent_datadog_installed_major: "{{ agent_datadog_installed_version.0 | default('', true) | string }}"
+    agent_datadog_installed_minor: "{{ agent_datadog_installed_version.1 | default('', true) | string }}"
+    agent_datadog_installed_bugfix: "{{ agent_datadog_installed_version.2 | default('', true) | string }}"
+  when: ansible_facts.os_family == "Windows" and agent_datadog_version_check_win.stdout | trim | length > 0

tasks/pkg-windows-opts.yml

@@ -125,3 +125,39 @@
   when: >-
     (agent_datadog_skip_install and (agent_datadog_major | int <= 7) and (agent_datadog_minor | int < 45)) and
     (("NPM" in agent_windows_active_features.stdout_lines) != agent_datadog_sysprobe_enabled)
+
+# Check if downgrade is requested (installed version is higher than requested version)
+- name: Initialize downgrade detection flag
+  ansible.builtin.set_fact:
+    agent_datadog_downgrade_detected: false
+
+- name: Detect if downgrade is requested
+  ansible.builtin.set_fact:
+    agent_datadog_downgrade_detected: true
+  when: >-
+    agent_datadog_installed_major is defined and
+    agent_datadog_installed_minor is defined and
+    agent_datadog_installed_bugfix is defined and
+    (
+      (agent_datadog_installed_major | int > agent_datadog_major | int) or
+      (agent_datadog_installed_major | int == agent_datadog_major | int and
+       agent_datadog_installed_minor | int > agent_datadog_minor | int) or
+      (agent_datadog_installed_major | int == agent_datadog_major | int and
+       agent_datadog_installed_minor | int == agent_datadog_minor | int and
+       agent_datadog_installed_bugfix | int > agent_datadog_bugfix | int)
+    )
+
+- name: Warn about downgrade
+  ansible.builtin.debug:
+    msg: >-
+      datadog_agent_version {{ agent_datadog_major }}.{{ agent_datadog_minor }}.{{ agent_datadog_bugfix }}
+      is lower than installed version
+      {{ agent_datadog_installed_major }}.{{ agent_datadog_installed_minor }}.{{ agent_datadog_installed_bugfix }},
+      proceeding to downgrade by uninstalling current version first
+  when: agent_datadog_downgrade_detected
+
+- name: Force reinstall for downgrade
+  ansible.builtin.set_fact:
+    agent_datadog_skip_install: false
+    agent_datadog_force_reinstall: true
+  when: agent_datadog_downgrade_detected

tasks/pkg-windows.yml

@@ -8,6 +8,17 @@
 - name: Include Windows opts tasks
   ansible.builtin.include_tasks: pkg-windows-opts.yml
 
+- name: Force skip install when requested
+  ansible.builtin.set_fact:
+    agent_datadog_skip_install: true
+  when: datadog_windows_skip_install | bool
+
+- name: Force Agent reinstall when requested
+  ansible.builtin.set_fact:
+    agent_datadog_force_reinstall: true
+    agent_datadog_skip_install: false
+  when: datadog_windows_force_reinstall | bool
+
 - name: Download windows datadog agent 614 fix script
   ansible.windows.win_get_url:
     url: "{{ datadog_windows_614_fix_script_url }}"
@@ -48,6 +59,37 @@
   register: agent_download_msi_result
   when: (not agent_datadog_skip_install) and (not ansible_check_mode)
 
+- name: Look up installed Datadog Agent product ids when forcing reinstall
+  ansible.windows.win_shell: |
+    $productName = "Datadog Agent"
+    $uninstallRoots = @(
+      "HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall",
+      "HKLM:\SOFTWARE\WOW6432Node\Microsoft\Windows\CurrentVersion\Uninstall"
+    )
+    $productIds = foreach ($root in $uninstallRoots) {
+      if (-not (Test-Path $root)) {
+        continue
+      }
+      Get-ItemProperty "$root\*" -ErrorAction SilentlyContinue |
+        Where-Object { $_.DisplayName -clike $productName } |
+        Select-Object -ExpandProperty PSChildName
+    }
+    $productIds | Sort-Object -Unique
+  register: agent_datadog_installed_product_ids_result
+  changed_when: false
+  check_mode: false
+  when:
+    - not agent_datadog_skip_install
+    - agent_datadog_force_reinstall
+
+- name: Cache installed product ids when available
+  ansible.builtin.set_fact:
+    agent_datadog_windows_installed_product_ids: "{{ agent_datadog_installed_product_ids_result.stdout_lines | select('match', '.+') | list }}"
+  when:
+    - not agent_datadog_skip_install
+    - agent_datadog_force_reinstall
+    - agent_datadog_installed_product_ids_result.stdout_lines | length > 0
+
 - name: Create Binary directory root (if not default)
   ansible.windows.win_file:
     path: "{{ datadog_windows_program_files_dir }}"
@@ -76,11 +118,16 @@
   when: datadog_windows_ddagentuser_password | default('', true) | length > 0
   no_log: true
 
-- name: Uninstall agent to update optional features
+- name: Uninstall installed Datadog Agent to update optional features or downgrade or because requested
   ansible.windows.win_package:
-    path: "{{ agent_download_msi_result.dest }}"
+    product_id: "{{ item }}"
     state: absent
-  when: not agent_datadog_skip_install and agent_datadog_force_reinstall
+  loop: "{{ agent_datadog_windows_installed_product_ids }}"
+  when:
+    - not agent_datadog_skip_install
+    - agent_datadog_force_reinstall
+    - agent_datadog_windows_installed_product_ids is defined
+    - agent_datadog_windows_installed_product_ids | length > 0
 
 - name: Install downloaded agent
   ansible.windows.win_package: