Fix public IP resolution when LB frontend uses static privateIPAddress

[Copilot]

Get-PublicIpReference only resolved public IPs via a publicIPAddress resource reference on the LB frontend config. When the frontend instead configured a static privateIPAddress from the public VIP logical network, the function returned $null and the outbound public IP was silently missed.

Changes

Get-PublicIpReference — return type changed from a plain resource ref string to PSCustomObject{ResourceRef, IPAddress}:

• publicIPAddress present → ResourceRef populated, caller fetches IP from resource
• privateIPAddress present (no publicIPAddress) → IPAddress populated directly, no secondary lookup needed

Get-SdnNetworkInterfaceOutboundPublicIPAddress — updated caller to branch on ResourceRef vs IPAddress:

if ($publicIpRef.ResourceRef) {
    # existing path: look up the publicIPAddress resource
    $publicIpAddress = Get-SdnResource @ncRestParams -ResourceRef $publicIpRef.ResourceRef
    ...
}
elseif ($publicIpRef.IPAddress) {
    # new path: static IP on LB frontend, no resource lookup
    [void]$arrayList.Add([PSCustomObject]@{
        ...
        PublicIPResourceRef = $null
        PublicIPAddress     = $publicIpRef.IPAddress
    })
}

Test coverage

• Added LB mock lb-outbound-0002 with privateIPAllocationMethod: Static / privateIPAddress: 40.40.40.6 on its frontend (no publicIPAddress resource ref)
• Added NIC mock tenantvm3 referencing this LB's backend pool
• Added Pester tests for all three resolution paths: direct instance-level publicIPAddress, LB frontend with publicIPAddress resource ref, LB frontend with static privateIPAddress

Change type

• Bug fix (non-breaking change)
• Code style update (formatting, local variables)
• New Feature (non-breaking change that adds new functionality without impacting existing)
• Breaking change (fix or feature that may cause functionality impact)
• Other

Checklist:

• My code follows the style and contribution guidelines of this project.
• I have tested and validated my code changes.

• Fixes Public IP for NIC is not properly identified if the LB FE config is a static IP address #178

[Copilot]

Copilot wasn't able to review any files in this pull request.

---

💡 Add a code-review agent skill or configure MCP servers for context-aware, tailored reviews. Learn more in the docs.

[Copilot]

Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated no new comments.

Suppressed comments (2)

src/modules/SdnDiag.NetworkController.psm1:285

• This fallback treats every non-empty load-balancer frontend privateIPAddress as public, but the condition never verifies the comment's required public VIP logical network. A frontend on a private logical subnet would therefore be returned as PublicIPAddress and can also trigger the public-IP trace path in SdnDiag.Common. Resolve the frontend subnet against LogicalNetworks and require isPublic (similar to Get-SdnPublicIPPoolUsageSummary) before returning it; include a private-subnet negative test.

                elseif (![string]::IsNullOrEmpty($frontendConfig.properties.privateIPAddress)) {

tests/offline/data/SdnApiResources/loadBalancers.json:90

• This subnet reference is dangling: logicalNetworks.json contains no PublicVIP resource, while its existing public subnet is /logicalNetworks/transit-0001/subnets/transit-subnet-0001 and its pool contains 40.40.40.6. Point this frontend at that fixture so the test data models a consistent Network Controller resource graph.

                "resourceRef": "/logicalNetworks/PublicVIP/subnets/PublicVIP-subnet-0001"

[Adam Rudell (arudell)]

Copilot will this new output change downstream callers in how they call into this function? What does the new output look like if I were to run this against a resource associated with publicIP resource, vs if set to static?

[Copilot]

Copilot will this new output change downstream callers in how they call into this function? What does the new output look like if I were to run this against a resource associated with publicIP resour...

No change is required for downstream public callers.

Get-PublicIpReference is an internal helper (only used inside Get-SdnNetworkInterfaceOutboundPublicIPAddress), and I updated that caller in the same change to handle both fields.

For the helper output:

• If frontend uses a publicIPAddress resource:

[pscustomobject]@{
  ResourceRef = '/publicIPAddresses/pip-outbound-0001'
  IPAddress   = $null
}

• If frontend uses static privateIPAddress (no publicIPAddress):

[pscustomobject]@{
  ResourceRef = $null
  IPAddress   = '40.40.40.6'
}

Public cmdlet output shape remains the same (PublicIPResourceRef, PublicIPAddress):

• resource-ref path => both populated (/publicIPAddresses/..., 40.40.40.4)
• static path => PublicIPResourceRef = $null, PublicIPAddress = '40.40.40.6'