to use and contribute to: **[AKS-Engine](https://github.com/Azure/aks-engine)**. The legacy [ACS-Engine](https://github.com/Azure/acs-engine) codebase has been deprecated in favor of AKS-engine.
The input to AKS-Engine is an apimodel JSON file describing the Kubernetes cluster. It is similar to the Azure Resource Manager (ARM) template syntax used to deploy a cluster directly with the Azure Kubernetes Service. The resulting output is an ARM template that can be checked into source control and used to deploy Kubernetes clusters to Azure.
The CoreOS Tectonic Installer for Azure is **open source** and available on GitHub for the community to use and contribute to: **[Tectonic Installer](https://github.com/coreos/tectonic-installer)**.
Tectonic Installer is a good choice when you need to make cluster customizations as it is built on [Hashicorp's Terraform](https://www.terraform.io/docs/providers/azurerm/) Azure Resource Manager (ARM) provider. This enables users to customize or integrate using familiar Terraform tooling.
You can get started using the [Tectonic Installer for Azure Guide](https://coreos.com/tectonic/docs/latest/install/azure/azure-terraform.html).