Adding an Azure PostgreSQL High Availability Check to Prowler | s1ns3nz0

Availability requirements for production databases need an operational failover design, not just backup retention. A restore can recover data, but it usually cannot provide the short interruption window expected for a critical PostgreSQL service.

Prowler PR #11046 adds postgresql_flexible_server_high_availability_enabled, which identifies Azure Database for PostgreSQL Flexible Servers without high availability enabled.

Why high availability matters

High availability provides a standby and managed failover path when a primary database component or its hosting zone fails. It reduces the time needed to restore service and lets application teams design around a known database continuity behavior.

Same-Zone and Zone-Redundant modes serve different availability boundaries. Teams should choose the mode that matches workload criticality and the regional architecture.

What the new check does

The check evaluates the PostgreSQL Flexible Server high-availability configuration.

It reports PASS when high availability is enabled.
It reports FAIL when the setting is disabled or absent.
It returns one finding per server, exposing gaps across subscriptions and environments.

The finding is a policy signal. Development or temporary systems may have different requirements, but production policy should be explicit.

Pair continuity with data recovery

Use HA to reduce service interruption and geo-redundant backups to recover from data loss or a wider regional event. Both are needed for a complete database resilience design. Include standby cost, capacity, and ownership in the service plan.

Enable Zone-Redundant HA on an eligible existing PostgreSQL server:

az postgres flexible-server update \
  --name <server-name> \
  --resource-group <resource-group> \
  --high-availability ZoneRedundant

The same configuration can be declared with Terraform. High availability requires a supported service tier.

resource "azurerm_postgresql_flexible_server" "example" {
  name                = "example-postgresql"
  resource_group_name = "example-rg"
  location            = "eastus"
  sku_name            = "GP_Standard_D2ds_v4"

  high_availability {
    mode = "ZoneRedundant"
  }
}

Exercise the application path

Test a planned failover with the application. Confirm retries, connection pooling, timeout handling, monitoring, and escalation procedures. A successful database failover does not guarantee uninterrupted service if clients cannot reconnect.

postgresql_flexible_server_high_availability_enabled makes an essential resilience decision measurable across cloud databases.

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