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From Scratch to Scalable: Seamless CI for C++ Windows Build Infrastructure with Ansible and Terraform

· 10 min read
Christopher McArthur

One of the biggest challenges in C++ is setting up CI from scratch and of that, the biggest pain point is the system administration which can be very disconnected from the development tools. In order to bridge this gap we can leverage Infrastructure as Code (IaC) targeting existing machines, locally in our network or in the cloud, is an excellent enhancement to ensure consistent reproducible builds. Having version controlled configuration management tied to the codebase is key, this will allow us to deterministically install all the tools required with confidence even in the far far future.

Let's walk through adding Ansible to handle configuring a Windows virtual machine. These ideas apply to Unix environments as well but we can tackle those in a future post. Once we've gained control over our build environments, we can tackle availability and scalability by introducing Terraform to help provision and initialize new Windows instances in Azure. This two prong solution enables both a path for migrating to the cloud and establishing a hybrid setup.

Let's get setup! To set up, start with a freshly-provisioned, fully patched VM from IT. Enable WinRM using a Group Policy Object for seamless remote management. If you are not connecting to a domain, follow the Ansible Setup Guide. Ansible's Windows support, coupled with its extensive library of built-in modules, streamlines configuration, often eliminating the need for manual PowerShell commands.

With that done, make sure to install Ansible and prepare to use it's Windows support. You'll need to add Chocolatey to Ansible support since it's not included by default, simply running ansible-galaxy collection install chocolatey.chocolatey will do the trick.

With everything setup, you are ready for the exciting bits (or bytes).

Configuring an Existing Machine

The various operations that are required to configure the machines are organized into Playbooks. With these we can specify a host with a list of tasks we want to execute. This declarative approach allows you to easily specify the final state.

We are going to focus on a cross-compiled applications whose toolchain focuses on Mingw-64 environment where developers primarily work with CMake and Ninja.

Let's make a playbook.yml!

- name: Install software on Windows machine
hosts: windows_vm
# There's lots of authentication options to pick from
ansible_user: username
ansible_password: password
- name: Install C++ dev tools using Chocolatey
name: "{{ item }}"
state: present
- mingw
- cmake
- ninja

This playbook will install Chocolatey if it's missing and then loop over the list of tools we provided. Running a playbook is simple, just run ansible-playbook playbook.yml.

Ansible has a "check mode" feature which is incredibly powerful to help prevent configuration drift. This is incredibly important if the build nodes are persistent and re-used for different CI/CD jobs; as scripts ran during the build process can modify the environment and have unintended consequences. This can be done with the same playbook by calling ansible-playbook --check playbook.yml which used to verify the integrity.


This can be scaled very easily with an inventory of hosts broken into groups which can be references as a whole. Making workflows like applying security updates to all the nodes seamless.

Easy enough.

In order to streamline setting up developer systems we are also going to include Visual Studio Code with a few extra extensions installed. For this we can going to add WinGet to the mix. This tool is the client to the Windows Package Manager service simplifies installing many Microsoft tools as well as popular software like video conferencing applications. For extra points with the developers, we are going to include their favorite VSCode extensions.

Adding developer tools to your playbook.yml
    - name: Install WinGet
name: winget-cli
state: present
- name: Install C++ IDE using WinGet
win_shell: |
winget install -e --id "{{ item }}"
- Microsoft.VisualStudioCode
- Microsoft.VisualStudio.2022.Enterprise.Preview
- name: Run PowerShell script
win_shell: |
$script = @"
# PowerShell script to activate and install software
Write-Host "Activate MSVC Enterprise 2022..."
"C:\Program Files\Microsoft Visual Studio\2022\Enterprise\Common7\IDE\StorePID.exe" AAAAA-BBBBB-CCCCC-DDDDD-EEEEE 09660

Write-Host "Installing VSCode Extensions..."
code --install-extension ms-vscode.cpptools-extension-pack
code --install-extension ms-vscode.cmake-tools

Write-Host "Verifying Installed Extensions..."
code --list-extensions --show-versions
Invoke-Expression -Command $script

One thing to take note is we can very easily run powershell scripts native on the machine. This gives use the flexibility to run extra commands like activating Visual Studio with our product key. Extra care is be needed if you want to preserve --check-mode when directly running powershell cmdlets.

With that, we can setup (and update) developer environments with all the tools they require while allowing verification that the correct tools are installed to prevent drift.

Pin Down Required Packages

For DevOps precision, meticulous version control of tools and dependencies is non-negotiable. It ensures a uniform environment across the development team, preventing compatibility issues and unpredictable behavior. The ability to pinpoint and manipulate specific versions empowers teams to troubleshoot and deliver software with a robust foundation.

Since we are using two different tools, we'll need to solve it for each of them respectively.

Going in order, we'll update Chocolatey to loop over the name and version we want to install and enable the pinned feature to prevent upgrades. Playbooks support YAML syntax which allows use to have custom JSON objects with individualized properties for our use case.

- name: Install C++ dev tools using Chocolatey
name: "{{ }}"
version: "{{ item.version }}" # Exact version
pinned: true # Only explicit upgrades
state: present
- { name: 'mingw', version: '13.2.0' }
- { name: 'cmake', version: '3.27.9' }
- { name: 'ninja', version: '1.11.0' }
- { name: 'winget-cli', version: '1.6.3482' }

As these are the tools used to make the final produced shipping to customers that we are testing with we want to make sure these are exactly same every single time.

Tackling WinGet, we'll use the pin command. Though Chocolatey has some support for version ranges, WinGet's is more complete and since it's only used for the developer tools, we can install the latest patch version with confidence.

    - name: Install C++ IDE using WinGet
win_shell: |
winget pin add -e --id "{{ }}" -v "{{ item.version_range }}"
winget install -e --id "{{ }}"
- { name: 'Microsoft.VisualStudioCode', version_range: '1.76.*' }
- { name: 'Microsoft.VisualStudio.2022.Enterprise.Preview', version_range: '17.6.*' }

Taking a Declarative Approach

Declarative code is often more concise and easier to read. Developers can focus on the desired result rather than navigating through detailed step-by-step instructions. Changes can be made to the underlying system or logic without altering the overall structure of the code. With less emphasis on explicit instructions, there's a reduced chance of introducing errors due to misunderstandings or misinterpretations of imperative commands.


For longevity, this separation between infrastructure and toolchain will help if you decided to transition to a Platform Engineering approach with an IDP (internal developer portal) for example.

Doing so is simple, we can run choco export packages.config to generate a list of dependencies. This will give us a manifest of all the tools installed on the system.

<?xml version="1.0" encoding="utf-8"?>
<package id="mingw" version="13.2.0" />
<package id="cmake" version="3.27.9" />
<package id="ninja" version="1.11.0" />
<package id="winget-cli" version="1.6.3482" />

For this example, the windows packages from WinGet are not critical for production builds, as such we'll skip those, but you are more then welcome to read their documentation for install --manifest.

Migrating to the Cloud

Here are the key advantages of incorporating cloud instances into a hybrid build infrastructure setup:

  1. Scalability and Elasticity:
    • Handle build spikes: Cloud instances can be provisioned quickly and on-demand, providing the flexibility to handle sudden surges in build requests or fluctuating workloads.
    • Reduce costs: Cloud resources can be scaled down during periods of low activity, optimizing resource usage and cost efficiency.
  2. Faster Build Times:
    • Access to powerful resources: Cloud instances often offer high-performance CPUs, GPUs, and large amounts of memory, accelerating build processes, especially for resource-intensive tasks.
    • Parallelization: Multiple cloud instances can be used in parallel to distribute builds across multiple machines, further reducing build times.
  3. Improved Developer Productivity:
    • Self-service provisioning: Developers can often provision cloud instances themselves, reducing reliance on IT teams and enabling faster access to build environments.
    • Experimentation and isolation: Cloud instances provide isolated environments for experimentation and testing, reducing the risk of affecting production systems.

It is possible to setup Windows VMs on Azure with both Terraform and Ansible, however this can be fairly involved. Here are some resources if you want to pursue that route.

Writing your own a provider to create a new Azure VM. Taking an extra step to join a domain or this alternative method.

Thankfully, there's a flourishing community around Terraform Windows Azure support and there are providers that can help make this very easy.
provider "azurerm" {
# Your Azure credentials
features {}

module "virtual-machine" {
source = "kumarvna/virtual-machine/azurerm"
version = "2.1.0"

# define resource group and subnet
virtual_machine_name = "win-machine"
os_flavor = "windows"
windows_distribution_name = "windows2019dc"
virtual_machine_size = "Standard_A2_v2"
admin_username = "azureadmin"
admin_password = "P@$$w0rd1234!"
instances_count = 1

nsg_inbound_rules = [
name = "winrm"
destination_port_range = "5986"
source_address_prefix = "*"

module "domain-join" {
source = "kumarvna/domain-join/azurerm"
version = "1.1.0"

virtual_machine_id = element(concat(module.virtual-machine.windows_virtual_machine_ids, [""]), 0)
active_directory_domain = ""
active_directory_username = "azureadmin"
active_directory_password = "P@$$w0rd1234!"

# Required TAGs for Azure resources

Now you can run Ansible normally with ansible-playbook -i '${terraform.virtual-machine.windows_vm_private_ips},' playbook.yml or you can add it as an extra step to the with:

  provisioner "local-exec" {
command = "ansible-playbook -i '${virtual-machine.windows_vm_private_ips},' playbook.yml"

Further Considerations

For a comprehensive understanding, let's address some additional aspects.

  • Testing. Testing. Testing. This would not be software engineering without a proper testing strategy.
  • Version scheme. Be able to track changes and re-deploy older environments when required.
  • Create costume base VM images on Azure
  • Handling Legacy systems, managing a Windows 7 machines for example, that do not support these tools.
  • Using KeyVault to a more secure automatic login reference
  • Using the WSL2 shell
  • Supporting Linux with Ansible


By embracing Infrastructure as Code (IaC), like Ansible and Terraform show in the post, you can empower your C++ build infrastructure with:

  • Streamlined Setup: Eliminate tedious manual configuration and ensure consistent, reproducible builds across build environments environments.
  • Scalability and Elasticity: Quickly adjust resources to handle sudden build spikes or fluctuating workloads, all while optimizing cost efficiency.
  • Improved Developer Productivity: Grant developers self-service provisioning and isolated, disposable environments for experimentation and testing.
  • Seamless Hybrid and Cloud Deployment: Bridge the gap between your local network and the cloud, enabling a flexible and future-proof approach to CI.

Take control of your C++ build process today. Embrace IaC and unlock the agility, efficiency, and scalability you need to deliver software faster and with greater confidence.