Establish and Document the Application's Hosting Infrastructure

This chapter explains how to establish and document the infrastructure on which an Application’s Instances are hosted. It addresses the infrastructure decisions made during design; the detailed infrastructure, configurations, and rules of each environment are addressed in the chapter “Establish and Document the Application’s Per-Environment Infrastructure, Configurations, and Rules.”

Establish the Hosting Infrastructure

During design, and in line with the Application’s Hosting Model, determine the infrastructure each Instance will run on, for example:

• Compute resources, such as servers, virtual machines, containers, or serverless functions.

• Storage, such as file storage and the storage used by databases.

• Network elements, such as networks, load balancers, firewalls, and connectivity to other Systems.

• Platform services, such as managed databases, messaging, and identity services.

• Regions, data centers, or cloud locations, including those used for Disaster Recovery.

For SaaS and vendor-hosted Applications, establish what the vendor provides and what, if anything, the enterprise provides, such as network connectivity, identity integration, or data transfer infrastructure.

Document and Share the Hosting Infrastructure

Record the hosting infrastructure for each Instance in the Application Documentation, preferably with a deployment diagram. Where infrastructure differs between Instances, record the differences explicitly, as described in the chapter “Establish and Document the Application’s Per-Environment Infrastructure, Configurations, and Rules.” Where infrastructure is defined as code, link to that code. Review the infrastructure documentation with every Release that changes it.

Best Practice: Establish and Document the Application’s Hosting Infrastructure

It is a best practice to both establish and document the solution for what an Application runs on: determine the compute, storage, network, platform, and location of each Instance, record them with deployment diagrams and any infrastructure code, and keep them current.

Benefits: Documented infrastructure lets operations teams diagnose failures and plan capacity, lets security teams assess exposure, and lets recovery teams rebuild an Instance if it is lost. It also makes infrastructure changes, migrations, and cost reviews far simpler, because the starting point is known.

Connections to Related IF4IT Practices and Inventories

The IT Operating Environments Best Practices addresses Environment Assets and the use of infrastructure-as-code. The Technology Portfolio Management (TPM) Best Practices and the Software Technologies Inventory and Attributes address the technologies on which Applications are hosted.