AgentPool resource demands setting of Count property when updating an autoscaled pool from non-autoscaled

What happened?

Trying to create an AgentPool where EnableAutoScaling is true. MaxCount, MinCount are set. Pulumi fails with

error: Code="InvalidParameter" Message="Required parameter properties.count is missing (null)." Target="properties.count"

Example

var tcServerPool = new AgentPool("teamcity-server", new AgentPoolArgs()
        {
            AgentPoolName = "tcserver",
            VmSize = "Standard_DS4_v2",
            EnableAutoScaling = true,
            MinCount = 0,
            MaxCount = 1,
            OsType = OSType.Linux,
            OsDiskSizeGB = 100,
            VnetSubnetID = subnetId,
            ResourceGroupName = groupName,
            ResourceName = clusterName,
            NodeTaints = new List<string>
            {
                "teamcity/server:NoSchedule"
            }
        });

Output of `pulumi about`

running 'dotnet build -nologo .'
  Determining projects to restore...

  All projects are up-to-date for restore.

  teamcity -> C:\Users\critc\source\drawboard-shared-infra\pulumi\teamcity\bin\Debug\net6.0\teamcity.dll

Build succeeded.

    0 Warning(s)
    0 Error(s)

Time Elapsed 00:00:00.96

'dotnet build -nologo .' completed successfully
CLI
Version      3.94.2
Go Version   go1.21.3
Go Compiler  gc

Plugins
NAME          VERSION
azure-native  2.21.0
dotnet        unknown
kubernetes    4.5.5
random        4.14.0

Host
OS       Microsoft Windows 11 Pro
Version  10.0.22621 Build 22621
Arch     x86_64

This project is written in dotnet: executable='C:\Program Files\dotnet\dotnet.exe' version='8.0.100'

Current Stack: drawboard/teamcity/dev

TYPE                                                 URN
pulumi:pulumi:Stack                                  urn:pulumi:dev::teamcity::pulumi:pulumi:Stack::teamcity-dev
pulumi:providers:pulumi                              urn:pulumi:dev::teamcity::pulumi:providers:pulumi::default
pulumi:providers:random                              urn:pulumi:dev::teamcity::pulumi:providers:random::default_4_14_0
random:index/randomPassword:RandomPassword           urn:pulumi:dev::teamcity::random:index/randomPassword:RandomPassword::sqlpassword
pulumi:pulumi:StackReference                         urn:pulumi:dev::teamcity::pulumi:pulumi:StackReference::shared-infra
pulumi:providers:kubernetes                          urn:pulumi:dev::teamcity::pulumi:providers:kubernetes::k8s
kubernetes:core/v1:Namespace                         urn:pulumi:dev::teamcity::kubernetes:core/v1:Namespace::teamcity
pulumi:providers:azure-native                        urn:pulumi:dev::teamcity::pulumi:providers:azure-native::default_2_21_0
kubernetes:core/v1:Secret                            urn:pulumi:dev::teamcity::kubernetes:core/v1:Secret::teamcitysa
kubernetes:core/v1:ConfigMap                         urn:pulumi:dev::teamcity::kubernetes:core/v1:ConfigMap::tc-config
kubernetes:rbac.authorization.k8s.io/v1:Role         urn:pulumi:dev::teamcity::kubernetes:rbac.authorization.k8s.io/v1:Role::teamcity-manageagents
kubernetes:apps/v1:StatefulSet                       urn:pulumi:dev::teamcity::kubernetes:apps/v1:StatefulSet::teamcity
azure-native:network:RecordSet                       urn:pulumi:dev::teamcity::azure-native:network:RecordSet::teamcity
kubernetes:core/v1:ServiceAccount                    urn:pulumi:dev::teamcity::kubernetes:core/v1:ServiceAccount::teamcity
kubernetes:rbac.authorization.k8s.io/v1:RoleBinding  urn:pulumi:dev::teamcity::kubernetes:rbac.authorization.k8s.io/v1:RoleBinding::teamcity-manageagents
azure-native:containerservice:AgentPool              urn:pulumi:dev::teamcity::azure-native:containerservice:AgentPool::teamcity-agents
kubernetes:core/v1:Service                           urn:pulumi:dev::teamcity::kubernetes:core/v1:Service::teamcity
kubernetes:networking.k8s.io/v1:Ingress              urn:pulumi:dev::teamcity::kubernetes:networking.k8s.io/v1:Ingress::teamcity
azure-native:containerservice:AgentPool              urn:pulumi:dev::teamcity::azure-native:containerservice:AgentPool::teamcity-server

Found no pending operations associated with drawboard/dev

Backend
Name           pulumi.com
URL            https://app.pulumi.com/samcritchley
User           samcritchley
Organizations  samcritchley, drawboard
Token type     personal

Dependencies:
NAME                VERSION
Pulumi              3.59.0
Pulumi.AzureNative  2.21.0
Pulumi.Kubernetes   4.5.5
Pulumi.Random       4.14.0

Pulumi locates its logs in C:\Users\critc\AppData\Local\Temp by default

Additional context

Specifying all 3 values is accepted on create:

            Count = 0,
            MinCount = 0,
            MaxCount = 1,
            EnableAutoScaling = true

Then set EnableAutoScaling to false

Fails with

 error: Code="InvalidParameter" Message="AgentPool 'tcagents' has 'agentPoolProfile.minCount' set which requires that 'agentPoolProfile.enableAutoscaling' is true and it is false"

So if we remove MinCount and MaxCount

EnableAutoScaling = false,
Count = 0,

Succeeds. Now a not-auto-scaled pool with 0 instances. Lets go back to auto scaling:

            EnableAutoScaling = true,
            Count = 0,
            MinCount = 0,
            MaxCount = 4,

Fails with

error: Code="InvalidParameter" Message="AgentPool 'tcagents' has set auto scaling as enabled but is not on Virtual Machine Scale Sets, this is not allowed. Please see https://aka.ms/aks-vmss-enablement for more details."

Hmm... lets set that then

Type = AgentPoolType.VirtualMachineScaleSets,

And it works. I didn't need to set this when I created the resource as an auto-scaling agent pool and need to when changing from non auto to auto. I get the sense the provider has done "something" for me when I created the resource and that same something is not happening in this update scenario.

Contributing

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pulumi / pulumi-azure-native