Fix flaky test by using dynamic port allocation instead of static counter

[Copilot]

The ExecDefaultContainerStdOut test was failing intermittently with "address already in use" errors when tests ran in parallel. The root cause was a static port counter in WebSocketTestBase that incremented from 13255, causing port conflicts when multiple test instances started simultaneously.

Changes

• Replace static port allocation with OS-assigned ports: Use http://127.0.0.1:0 instead of incrementing port counter
• Eagerly bind ports in constructor: Start the host immediately to acquire the assigned port, then retrieve the actual address via IServerAddressesFeature
• Remove redundant host startup: Delete Host.StartAsync() call from test since host is already running
• Clarify property mutability: Add explicit private set to ServerBaseAddress and WebSocketBaseAddress properties

This follows the same pattern already used in MockKubeApiServer elsewhere in the codebase.

// Before: static port counter caused conflicts
private static int nextPort = 13255;
int port = Interlocked.Increment(ref nextPort);
ServerBaseAddress = new Uri($"http://localhost:{port}");

// After: OS assigns available port dynamically
Host = WebHost.CreateDefaultBuilder()
    .UseUrls("http://127.0.0.1:0")
    .Build();
Host.Start();

var serverAddress = Host.ServerFeatures.Get<IServerAddressesFeature>()?.Addresses.FirstOrDefault();
ServerBaseAddress = new Uri(serverAddress);

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• crl.comodoca.com
  • Triggering command: /home/REDACTED/work/csharp/.codeql-scratch/dbs/csharp/working/.dotnet/dotnet /home/REDACTED/work/csharp/.codeql-scratch/dbs/csharp/working/.dotnet/dotnet restore --no-dependencies /home/REDACTED/work/csharp/csharp/src/KubernetesClient.Classic/KubernetesClient.Classic.csproj --packages /home/REDACTED/work/csharp/.codeql-scratch/dbs/csharp/working/packages /p:DisableImplicitNuGetFallbackFolder=true --verbosity normal /p:TargetFrameworkRootPath=/home/REDACTED/work/csharp/.codeql-scratch/dbs/csharp/working/emptyFakeDotnetRoot /p:NetCoreTargetingPackRoot=/home/REDACTED/work/csharp/.codeql-scratch/dbs/csharp/working/emptyFakeDotnetRoot (dns block)
• idp.issuer.url
  • Triggering command: /usr/share/dotnet/dotnet /usr/share/dotnet/dotnet exec --runtimeconfig /home/REDACTED/work/csharp/csharp/tests/KubernetesClient.Tests/bin/Debug/net8.0/KubernetesClient.Tests.runtimeconfig.json --depsfile /home/REDACTED/work/csharp/csharp/tests/KubernetesClient.Tests/bin/Debug/net8.0/KubernetesClient.Tests.deps.json /home/REDACTED/work/csharp/csharp/tests/KubernetesClient.Tests/bin/Debug/net8.0/testhost.dll --port 45675 --endpoint 127.0.0.1:045675 --role client --parentprocessid 6013 --telemetryoptedin false (dns block)
  • Triggering command: /usr/share/dotnet/dotnet /usr/share/dotnet/dotnet exec --runtimeconfig /home/REDACTED/work/csharp/csharp/tests/KubernetesClient.Tests/bin/Debug/net9.0/KubernetesClient.Tests.runtimeconfig.json --depsfile /home/REDACTED/work/csharp/csharp/tests/KubernetesClient.Tests/bin/Debug/net9.0/KubernetesClient.Tests.deps.json /home/REDACTED/work/csharp/csharp/tests/KubernetesClient.Tests/bin/Debug/net9.0/testhost.dll --port 45053 --endpoint 127.0.0.1:045053 --role client --parentprocessid 6052 --telemetryoptedin false (dns block)
  • Triggering command: /usr/share/dotnet/dotnet /usr/share/dotnet/dotnet exec --runtimeconfig /home/REDACTED/work/csharp/csharp/tests/KubernetesClient.Tests/bin/Debug/net10.0/KubernetesClient.Tests.runtimeconfig.json --depsfile /home/REDACTED/work/csharp/csharp/tests/KubernetesClient.Tests/bin/Debug/net10.0/KubernetesClient.Tests.deps.json /home/REDACTED/work/csharp/csharp/tests/KubernetesClient.Tests/bin/Debug/net10.0/testhost.dll --port 41007 --endpoint 127.0.0.1:041007 --role client --parentprocessid 6053 --telemetryoptedin false (dns block)
• ocsp.comodoca.com
  • Triggering command: /home/REDACTED/work/csharp/.codeql-scratch/dbs/csharp/working/.dotnet/dotnet /home/REDACTED/work/csharp/.codeql-scratch/dbs/csharp/working/.dotnet/dotnet restore --no-dependencies /home/REDACTED/work/csharp/csharp/src/KubernetesClient.Classic/KubernetesClient.Classic.csproj --packages /home/REDACTED/work/csharp/.codeql-scratch/dbs/csharp/working/packages /p:DisableImplicitNuGetFallbackFolder=true --verbosity normal /p:TargetFrameworkRootPath=/home/REDACTED/work/csharp/.codeql-scratch/dbs/csharp/working/emptyFakeDotnetRoot /p:NetCoreTargetingPackRoot=/home/REDACTED/work/csharp/.codeql-scratch/dbs/csharp/working/emptyFakeDotnetRoot (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

Original prompt

fix flaky test

[xUnit.net 00:05:03.72] Can exec in pod's default container, STDOUT only [FAIL]
Failed Can exec in pod's default container, STDOUT only [59 ms]
Error Message:
System.IO.IOException : Failed to bind to address http://127.0.0.1:13260: address already in use.
---- Microsoft.AspNetCore.Connections.AddressInUseException : Only one usage of each socket address (protocol/network address/port) is normally permitted.
-------- System.Net.Sockets.SocketException : Only one usage of each socket address (protocol/network address/port) is normally permitted.

---

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[tg123]

/LGTM

I thought it is a global webhost issue, seems websocket test only

[Copilot]

Pull request overview

This PR fixes a flaky test issue caused by port conflicts when tests run in parallel. The solution replaces a static port counter with OS-assigned dynamic ports, following the same pattern already established by MockKubeApiServer in the codebase.

Key Changes

• Switched from static port allocation (incrementing from 13255) to OS-assigned ports using http://127.0.0.1:0
• Eagerly start the web host in the constructor to acquire and retrieve the assigned port via IServerAddressesFeature
• Removed redundant Host.StartAsync() call from test since host is now started in base class constructor

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
tests/KubernetesClient.Tests/WebSocketTestBase.cs	Replaced static port counter with OS-assigned port allocation, added logic to retrieve actual port from server features, and made property setters explicit
tests/KubernetesClient.Tests/PodExecTests.cs	Removed redundant Host.StartAsync() call now that host is started in base class constructor

---

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[Copilot]

The string replacement approach serverAddress.Replace("http://", "ws://") could be fragile. Consider using UriBuilder for a more robust conversion:

var uriBuilder = new UriBuilder(serverAddress)
{
    Scheme = "ws"
};
WebSocketBaseAddress = uriBuilder.Uri;

This handles edge cases better (e.g., https/wss, preserving all URI components).

Suggested change

	WebSocketBaseAddress = new Uri(serverAddress.Replace("http://", "ws://"));
	var uriBuilder = new UriBuilder(serverAddress)
	{
	Scheme = "ws"
	};
	WebSocketBaseAddress = uriBuilder.Uri;

[brendandburns]

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: brendandburns, Copilot

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• OWNERS [brendandburns]

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