Load balancers should be zone-redundant#
Reliability · Load Balancer · Rule · 2021_09
Load balancers deployed with Standard SKU should be zone-redundant for high availability.
Description#
Load balancers using availability zones improve reliability and ensure availability during failure scenarios affecting a data center within a region. A single zone redundant frontend IP address will survive zone failure. The frontend IP may be used to reach all (non-impacted) backend pool members no matter the zone. One or more availability zones can fail and the data path survives as long as one zone in the region remains healthy.
Recommendation#
Consider using zone-redundant load balancers deployed with Standard SKU.
Notes#
This rule applies when analyzing resources deployed to Azure using pre-flight and in-flight data.
This rule fails when "zones" is constrained to a single(zonal) zone, and passes when set to null, [] or ["1", "2", "3"].
Examples#
Configure with Azure template#
To configure zone-redundancy for a load balancer.
- Set
sku.nametoStandard. - Set
properties.frontendIPConfigurations[*].zonesto["1", "2", "3"].
For example:
{
"apiVersion": "2020-07-01",
"name": "[parameters('name')]",
"type": "Microsoft.Network/loadBalancers",
"location": "[parameters('location')]",
"dependsOn": [],
"tags": {},
"properties": {
"frontendIPConfigurations": [
{
"name": "frontend-ip-config",
"properties": {
"privateIPAddress": null,
"privateIPAddressVersion": "IPv4",
"privateIPAllocationMethod": "Dynamic",
"subnet": {
"id": "/subscriptions/xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx/resourceGroups/lb-rg/providers/Microsoft.Network/virtualNetworks/lb-vnet/subnets/default"
}
},
"zones": [
"1",
"2",
"3"
]
}
],
"backendAddressPools": [],
"probes": [],
"loadBalancingRules": [],
"inboundNatRules": [],
"outboundRules": []
},
"sku": {
"name": "[parameters('sku')]",
"tier": "[parameters('tier')]"
}
}
Configure with Bicep#
To configure zone-redundancy for a load balancer.
- Set
sku.nametoStandard. - Set
properties.frontendIPConfigurations[*].zonesto['1', '2', '3'].
For example:
resource lb_001 'Microsoft.Network/loadBalancers@2021-02-01' = {
name: lbName
location: location
sku: {
name: 'Standard'
}
properties: {
frontendIPConfigurations: [
{
name: 'frontendIPConfig'
properties: {
privateIPAllocationMethod: 'Dynamic'
subnet: {
id: vnet.properties.subnets[1].id
}
}
zones: [
'1'
'2'
'3'
]
}
]
}
}