# Azure Application Gateway

> Application Gateway bills hourly per deployed gateway plus capacity units that scale with load, so a v2 gateway in a quiet dev environment often outspends the apps behind it. ZopNight surfaces request volume from 60 days of Azure Monitor metrics and flags gateways that are idle or oversized for their traffic.

Source: https://zop.dev/integrations/azure/app-gateway
Updated: 2026-08-19

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Application Gateway is Azure's Layer-7 load balancer with WAF capability, billed hourly per gateway plus capacity units. An always-on gateway in a dev environment often costs more than the workloads behind it.

## Gateway-hours plus capacity units

An Application Gateway v2 bills a fixed hourly charge for existing at all, plus capacity units measured on compute, persistent connections, and throughput. The fixed portion never drops to zero: a gateway with a minimum autoscale instance count holds that floor around the clock, and WAF-enabled SKUs carry a higher rate for both meters. The result is a resource whose bill is dominated by its configuration rather than its traffic. The gateway sized and hardened for production works exactly the same way, financially, when cloned into an environment that sees a handful of requests a day.

## Request-volume evidence over 60 days

Discovered via Azure Resource Graph with SKU and capacity detail. Azure Monitor metrics with a 60-day lookback reveal request volume, Cost Management billing attributes spend, and recommendations flag idle or oversized gateways. Application Gateway exposes no stop operation ZopNight can schedule, so its role here is evidentiary: two months of request counts placed next to the gateway's fixed spend makes the idle case unarguable, and the oversized case (a high minimum instance count that traffic never justifies) visible without guesswork.

## Where Application Gateway spend goes wrong

Three patterns dominate. Per-environment clones: templates that stamp a WAF v2 gateway into dev and staging replicate production's most expensive networking fixture in front of near-zero traffic. Inflated autoscale floors: a minimum instance count raised during an incident and never lowered turns a temporary safeguard into a permanent charge. Abandoned gateways: the backend app was decommissioned, but the gateway, its listeners, and its public IP remain deployed and metering hourly.

## Locating gateways in the Azure portal

Azure portal → Application gateways lists each gateway with its tier and state. For any candidate, the Metrics blade's request-count chart over a long range tells you in one glance whether the hourly meter is buying anything.