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.

---

💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: Copilot
Once this PR has been reviewed and has the lgtm label, please ask for approval from tg123. For more information see the Code Review Process.

The full list of commands accepted by this bot can be found here.

Needs approval from an approver in each of these files:

• OWNERS

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: Copilot
Once this PR has been reviewed and has the lgtm label, please ask for approval from tg123. For more information see the Code Review Process.

The full list of commands accepted by this bot can be found here.

Needs approval from an approver in each of these files:

• OWNERS

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[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

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[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;