John Folberth continues his series on Azure DevOps Pipelines, by Leveraging Stages with YAML Objects.

Introduction

By now we’ve covered the basics on tasks, jobs, stages, environments, variables and templates for jobs and tasks. It is now time to move towards stage templates. Additionally, to assist with templating we will cover one way to leverage YAML objects which is a key tool when templating up and keeping your pipelines DRY (Don’t Repeat Yourself). 

To follow along I am leveraging non-ADO code in from Azure IaC Flavors and YAML templates from TheYAMLPipelineOne 

Stages

Recapping from a previous post, a stage is: 

Stages are the level above jobs. A stage is required; however, there is a default if one is not provided. A stage can contain one to many jobs and acts as a logical grouping of related jobs. 

An important component to understand is that Azure DevOps, out of the box, provide an easy way to rerun Pipelines at the stage level. This means our stages should be constructed with jobs that make sense to re-run together. Usually, customers want to naturally associate a stage with a customer environment. I’d advise fighting this temptation. 

Picking up on this notion, I tend to recommend a stage can be combination of app components (data, front end, infrastructure, etc..) and deployment target (region, virtual machine, etc..). By making this distinction it helps keep our stages scoped to an easily and targeted deployment path. 

When stopping to think about this our stages, specifically between a test and production environment, should be exactly the same minus the deployment target information and environment settings. Thus, they are a great candidate for templates. 

So why weren’t these covered in jobs and task templates in the previous article? Stages are the container that houses all of the deployment jobs. As such extra thought should be placed into how to architect these to scale out infinitely. It shouldn’t matter if I am deploying to one or twenty locations. They all should contain the same jobs, tasks, and appropriate variables. Deploying to one stage or two stages with the same template is easy….but how to do it for infinite possibilities? Enter YAML Objects. 

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