/azure-reliability

Multi-Region & Failover Checks

Overview

Multi-region deployment protects against entire region outages. This requires deploying compute in multiple regions and using a global load balancer (Azure Front Door or Traffic Manager) to route traffic.

Resource Graph Queries

⚠️ Output format: Use --query "data[]" -o json (not -o table). az graph query -o table only renders summary columns and does not show projected fields.

Check if App is Deployed in Multiple Regions

az graph query -q "
Resources
| where type in~ ('microsoft.web/sites', 'microsoft.app/containerapps')
| extend appKind = case(
    type =~ 'microsoft.web/sites' and kind contains 'functionapp', 'FunctionApp',
    type =~ 'microsoft.web/sites', 'WebApp',
    type =~ 'microsoft.app/containerapps', 'ContainerApp',
    'Other')
| extend baseName = extract('^(.+?)(-[a-z]+\\d*)?$', 1, name)
| summarize regions=make_list(location), regionCount=dcount(location), apps=make_list(name) by baseName, appKind
| where regionCount > 1
| project baseName, appKind, regionCount, regions, apps
" --query "data[]" -o json

Interpretation:

• Results show apps with the same base name deployed across multiple regions → ✅ Multi-region
• No results → ❌ All apps are single-region

Important: The baseName extraction uses a naming convention (e.g., my-app-eastus, my-app-westus). If apps don't follow this pattern, also check by resource tags:

az graph query -q "
Resources
| where type in~ ('microsoft.web/sites', 'microsoft.app/containerapps')
| where isnotempty(tags['app-group']) or isnotempty(tags['application'])
| extend appGroup = coalesce(tostring(tags['app-group']), tostring(tags['application']))
| summarize regions=make_list(location), regionCount=dcount(location) by appGroup
| where regionCount > 1
| project appGroup, regionCount, regions
" --query "data[]" -o json

Check for Azure Front Door

az graph query -q "
Resources
| where type =~ 'microsoft.cdn/profiles'
| where sku.name =~ 'Standard_AzureFrontDoor' or sku.name =~ 'Premium_AzureFrontDoor'
| project name, resourceGroup, sku=sku.name
" --query "data[]" -o json

Check for Traffic Manager Profiles

az graph query -q "
Resources
| where type =~ 'microsoft.network/trafficmanagerprofiles'
| extend routingMethod = tostring(properties.trafficRoutingMethod)
| extend endpoints = array_length(properties.endpoints)
| project name, resourceGroup, routingMethod, endpoints, status=properties.profileStatus
" --query "data[]" -o json

Check Front Door Origins/Backends

# List Front Door origin groups and origins
az afd origin-group list \
  --profile-name <front-door-name> \
  --resource-group <rg> \
  --query "[].{name:name, origins:length(origins)}" -o table

az afd origin list \
  --profile-name <front-door-name> \
  --resource-group <rg> \
  --origin-group-name <group-name> \
  --query "[].{name:name, hostName:hostName, priority:priority, weight:weight}" -o table

Assessment Criteria

Multi-Region Patterns

Active-Passive (Recommended starting point)

Users → Azure Front Door → Primary Region (priority 1)
                        → Secondary Region (priority 2, standby)

• Primary serves all traffic
• Front Door health probes detect primary failure
• Automatic failover to secondary
• Lower cost (secondary can be scaled down)

Active-Active

Users → Azure Front Door → Region A (weight 50)
                        → Region B (weight 50)

• Both regions serve traffic simultaneously
• Better performance (route to nearest)
• Higher cost (both at full capacity)
• Requires stateless design or data sync

Remediation: Generate Multi-Region IaC

When user wants multi-region, generate Bicep that includes:

1. Secondary region compute — Same service type as primary
2. Secondary region storage — ZRS in secondary region
3. Azure Front Door profile — With:
   • Origin group containing both regions
   • Health probe (HTTP/HTTPS to health endpoint)
   • Routing rule (priority for active-passive, weighted for active-active)
4. DNS configuration — Custom domain on Front Door

Bicep Skeleton for Active-Passive Front Door

resource frontDoor 'Microsoft.Cdn/profiles@2024-02-01' = {
  name: frontDoorName
  location: 'global'
  sku: {
    name: 'Standard_AzureFrontDoor'
  }
}

resource originGroup 'Microsoft.Cdn/profiles/originGroups@2024-02-01' = {
  parent: frontDoor
  name: 'primary-group'
  properties: {
    healthProbeSettings: {
      probePath: '/api/health'
      probeProtocol: 'Https'
      probeIntervalInSeconds: 30
    }
    loadBalancingSettings: {
      sampleSize: 4
      successfulSamplesRequired: 3
    }
  }
}

resource primaryOrigin 'Microsoft.Cdn/profiles/originGroups/origins@2024-02-01' = {
  parent: originGroup
  name: 'primary'
  properties: {
    hostName: primaryAppHostName
    priority: 1
    weight: 1000
    originHostHeader: primaryAppHostName
  }
}

resource secondaryOrigin 'Microsoft.Cdn/profiles/originGroups/origins@2024-02-01' = {
  parent: originGroup
  name: 'secondary'
  properties: {
    hostName: secondaryAppHostName
    priority: 2
    weight: 1000
    originHostHeader: secondaryAppHostName
  }
}

Reporting

For the reliability checklist, mark the Multi-Region column per resource:

• ✅ — resource is deployed in ≥2 regions AND fronted by Azure Front Door / Traffic Manager with health probes
• ❌ — single region OR multi-region without an active global load balancer / health probes
• For Front Door / Traffic Manager rows: ✅ if configured with health probes, ❌ if absent or missing health probes