Azure App Service

What it is

Azure App Service is a managed HTTP application host. Azure operates the underlying platform and runtime plumbing while the owner deploys code or a container and configures application settings, networking, certificates, scaling, and diagnostics.

Prerequisites and mechanics

Understand HTTP, DNS, TLS, processes, environment configuration, and App Service plans. An app runs inside a plan, so apps in one plan share its compute boundary and scaling decision. A deployment slot is a separate app instance boundary used to warm or validate a version; swapping changes which slot receives production traffic.

Relationships and choices

App Service hosts a web workload; Functions is trigger-oriented serverless compute; a container image is a packaging format, not a hosting service. Choose App Service when the workload is a continuously hosted web/API application and you want a managed platform. Choose a VM when you need OS control; choose Functions when event-triggered execution is the primary shape.

The pipeline deploys an artifact or image to a slot; the slot emits telemetry to Application Insights; a swap promotes the tested version. A common failure is a setting or certificate that is slot-specific or a plan reaching capacity, causing the new slot to behave differently from production.

Worked example and route

Deploy an API to staging, set its connection configuration there, test its health endpoint, then swap it into production. A rollback swaps the previous version back only if the failure is in the application version; a platform or data migration failure needs a different recovery decision. This appears in AZ-104 compute and AZ-204 runtime/deployment modules.

Re-audit

Re-open when App Service hosting, slot, TLS, scaling, or deployment behavior changes. Sources checked 2026-08-31: App Service overview and deployment slots.