Multivendor Provisioning

The Azure Resource Manager (ARM) is the recommended approach to provisioning infrastructure resources in Azure. Sometimes there is a need to provision all or some of the resources for an application outside Azure. These can be resources in a private cloud, another public cloud, or even some other hosted services like the hosted Elasticsearch services offered by Found (http://found.no).

There are a lot of different ways to approach this. We could use a combination or custom scripts for provisioning the other resource and then deploying the Azure resources through ARM using either the declarative or imperative model. We could transform the ARM templates as needed, or even have an ARM template invoke custom provisioning scripts to configure these resources. In addition to those options, there are some other infrastructure provisioning orchestration tools available in the market that enable us to define our infrastructure in a cloud platform vendor-agnostic way, and then use cloud-specific providers to do that actual work of provisioning. An example of one such tool is Terraform (http://terraform.io). Terraform is capable of provisioning Azure infrastructure through an ARM-based provider, along with some other popular cloud platforms.

Terraform, by HashiCorp, is a tool for building, changing, and versioning infrastructure in a safe, efficient, and consistent way. Using configuration files that describe the final state of an application, Terraform generates and runs an execution plan that builds the necessary infrastructure. Terraform can be used to manage tasks as small as individual computing resource allocations or as large as multivendor cloud deployments.

Terraform integrates with different resources through the use of providers. Providers form a bridge between the Terraform configuration and any underlying APIs, services, or platforms. The Azure provider enables you to provision and manage Azure resources, including virtual machine instances, security groups, storage devices, databases, virtual networks, and more. This tool can be useful when you need to define and provision infrastructure on multiple cloud platforms.