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Implement KubectlTop for node and pod metrics (#1703)
* Initial plan * Implement KubectlTop with TopNodes and TopPods methods Co-authored-by: brendandburns <5751682+brendandburns@users.noreply.github.com> * Update metrics example to demonstrate KubectlTop usage Co-authored-by: brendandburns <5751682+brendandburns@users.noreply.github.com> --------- Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com> Co-authored-by: brendandburns <5751682+brendandburns@users.noreply.github.com>
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‎examples/metrics/Program.cs‎

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using k8s;
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using k8s.kubectl.beta;
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using System;
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using System.Linq;
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using System.Threading.Tasks;
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}
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}
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async Task TopNodes(Kubectl kubectl)
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{
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Console.WriteLine("=== Top Nodes by CPU ===");
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var topNodesCpu = kubectl.TopNodes("cpu");
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// Show top 5
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var topNodesCpuList = topNodesCpu.Take(5).ToList();
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foreach (var item in topNodesCpuList)
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{
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var cpuUsage = item.Metrics.Usage["cpu"];
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var cpuCapacity = item.Resource.Status.Capacity["cpu"];
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var cpuPercent = (cpuUsage.ToDouble() / cpuCapacity.ToDouble()) * 100;
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Console.WriteLine($"{item.Resource.Metadata.Name}: CPU {cpuUsage} / {cpuCapacity} ({cpuPercent:F2}%)");
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}
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Console.WriteLine(Environment.NewLine);
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Console.WriteLine("=== Top Nodes by Memory ===");
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var topNodesMemory = kubectl.TopNodes("memory");
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// Show top 5
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var topNodesMemoryList = topNodesMemory.Take(5).ToList();
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foreach (var item in topNodesMemoryList)
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{
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var memUsage = item.Metrics.Usage["memory"];
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var memCapacity = item.Resource.Status.Capacity["memory"];
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var memPercent = (memUsage.ToDouble() / memCapacity.ToDouble()) * 100;
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Console.WriteLine($"{item.Resource.Metadata.Name}: Memory {memUsage} / {memCapacity} ({memPercent:F2}%)");
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}
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}
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async Task TopPods(Kubectl kubectl)
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{
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Console.WriteLine("=== Top Pods by CPU (kube-system namespace) ===");
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var topPodsCpu = kubectl.TopPods("kube-system", "cpu");
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// Show top 5
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var topPodsCpuList = topPodsCpu.Take(5).ToList();
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foreach (var item in topPodsCpuList)
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{
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var cpuSum = item.Metrics.Containers.Sum(c =>
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c.Usage.ContainsKey("cpu") ? c.Usage["cpu"].ToDouble() : 0);
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Console.WriteLine($"{item.Resource.Metadata.Name}: CPU {cpuSum:F3} cores");
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}
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Console.WriteLine(Environment.NewLine);
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Console.WriteLine("=== Top Pods by Memory (kube-system namespace) ===");
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var topPodsMemory = kubectl.TopPods("kube-system", "memory");
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// Show top 5
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var topPodsMemoryList = topPodsMemory.Take(5).ToList();
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foreach (var item in topPodsMemoryList)
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{
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var memSum = item.Metrics.Containers.Sum(c =>
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c.Usage.ContainsKey("memory") ? c.Usage["memory"].ToDouble() : 0);
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Console.WriteLine($"{item.Resource.Metadata.Name}: Memory {memSum / (1024 * 1024):F2} MiB");
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}
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}
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var config = KubernetesClientConfiguration.BuildConfigFromConfigFile();
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var client = new Kubernetes(config);
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var kubectl = new Kubectl(client);
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Console.WriteLine("=== Raw Metrics API ===");
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await NodesMetrics(client).ConfigureAwait(false);
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Console.WriteLine(Environment.NewLine);
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await PodsMetrics(client).ConfigureAwait(false);
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Console.WriteLine(Environment.NewLine);
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Console.WriteLine("=== Kubectl Top API ===");
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await TopNodes(kubectl).ConfigureAwait(false);
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Console.WriteLine(Environment.NewLine);
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await TopPods(kubectl).ConfigureAwait(false);

‎examples/metrics/metrics.csproj‎

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<OutputType>Exe</OutputType>
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</PropertyGroup>
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<ItemGroup>
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<ProjectReference Include="..\..\src\KubernetesClient.Kubectl\KubernetesClient.Kubectl.csproj" />
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</ItemGroup>
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</Project>

‎src/KubernetesClient.Kubectl/Beta/AsyncKubectl.Top.cs‎

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using k8s.Models;
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namespace k8s.kubectl.beta;
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public partial class AsyncKubectl
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{
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/// <summary>
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/// Describes a pair of Kubernetes resource and its metrics.
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/// </summary>
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/// <typeparam name="TResource">The type of Kubernetes resource.</typeparam>
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/// <typeparam name="TMetrics">The type of metrics.</typeparam>
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public class ResourceMetrics<TResource, TMetrics>
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{
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/// <summary>
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/// Gets or sets the Kubernetes resource.
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/// </summary>
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public required TResource Resource { get; set; }
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/// <summary>
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/// Gets or sets the metrics for the resource.
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/// </summary>
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public required TMetrics Metrics { get; set; }
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}
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/// <summary>
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/// Get top nodes sorted by CPU or memory usage.
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/// </summary>
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/// <param name="metric">The metric to sort by ("cpu" or "memory"). Defaults to "cpu".</param>
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/// <param name="cancellationToken">Cancellation token.</param>
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/// <returns>A list of nodes with their metrics, sorted by the specified metric in descending order.</returns>
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public async Task<List<ResourceMetrics<V1Node, NodeMetrics>>> TopNodesAsync(string metric = "cpu", CancellationToken cancellationToken = default)
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{
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if (metric != "cpu" && metric != "memory")
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{
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throw new ArgumentException("Metric must be either 'cpu' or 'memory'", nameof(metric));
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}
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// Get all nodes
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var nodes = await client.CoreV1.ListNodeAsync(cancellationToken: cancellationToken).ConfigureAwait(false);
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// Get node metrics
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var nodeMetrics = await client.GetKubernetesNodesMetricsAsync().ConfigureAwait(false);
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// Create a dictionary for quick lookup of metrics by node name
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var metricsDict = nodeMetrics.Items.ToDictionary(m => m.Metadata.Name, m => m);
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// Combine nodes with their metrics and calculate percentage
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var result = new List<ResourceMetrics<V1Node, NodeMetrics>>();
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foreach (var node in nodes.Items)
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{
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if (metricsDict.TryGetValue(node.Metadata.Name, out var metrics))
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{
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result.Add(new ResourceMetrics<V1Node, NodeMetrics>
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{
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Resource = node,
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Metrics = metrics,
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});
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}
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}
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// Sort by metric value (percentage of capacity) in descending order
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result.Sort((a, b) =>
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{
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var percentageA = CalculateNodePercentage(a.Resource, a.Metrics, metric);
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var percentageB = CalculateNodePercentage(b.Resource, b.Metrics, metric);
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return percentageB.CompareTo(percentageA); // Descending order
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});
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return result;
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}
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/// <summary>
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/// Get top pods in a namespace sorted by CPU or memory usage.
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/// </summary>
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/// <param name="namespace">The namespace to get pod metrics from.</param>
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/// <param name="metric">The metric to sort by ("cpu" or "memory"). Defaults to "cpu".</param>
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/// <param name="cancellationToken">Cancellation token.</param>
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/// <returns>A list of pods with their metrics, sorted by the specified metric in descending order.</returns>
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public async Task<List<ResourceMetrics<V1Pod, PodMetrics>>> TopPodsAsync(string @namespace, string metric = "cpu", CancellationToken cancellationToken = default)
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{
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if (string.IsNullOrEmpty(@namespace))
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{
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throw new ArgumentException("Namespace cannot be null or empty", nameof(@namespace));
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}
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if (metric != "cpu" && metric != "memory")
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{
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throw new ArgumentException("Metric must be either 'cpu' or 'memory'", nameof(metric));
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}
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// Get all pods in the namespace
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var pods = await client.CoreV1.ListNamespacedPodAsync(@namespace, cancellationToken: cancellationToken).ConfigureAwait(false);
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// Get pod metrics for the namespace
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var podMetrics = await client.GetKubernetesPodsMetricsByNamespaceAsync(@namespace).ConfigureAwait(false);
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// Create a dictionary for quick lookup of metrics by pod name
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var metricsDict = podMetrics.Items.ToDictionary(m => m.Metadata.Name, m => m);
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// Combine pods with their metrics
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var result = new List<ResourceMetrics<V1Pod, PodMetrics>>();
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foreach (var pod in pods.Items)
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{
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if (metricsDict.TryGetValue(pod.Metadata.Name, out var metrics))
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{
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result.Add(new ResourceMetrics<V1Pod, PodMetrics>
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{
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Resource = pod,
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Metrics = metrics,
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});
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}
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}
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// Sort by metric value (sum across all containers) in descending order
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result.Sort((a, b) =>
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{
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var sumA = CalculatePodMetricSum(a.Metrics, metric);
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var sumB = CalculatePodMetricSum(b.Metrics, metric);
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return sumB.CompareTo(sumA); // Descending order
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});
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return result;
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}
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/// <summary>
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/// Calculate the percentage of node capacity used by the specified metric.
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/// </summary>
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private static double CalculateNodePercentage(V1Node node, NodeMetrics metrics, string metric)
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{
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if (metrics?.Usage == null || !metrics.Usage.TryGetValue(metric, out var usage))
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{
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return 0;
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}
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if (node?.Status?.Capacity == null || !node.Status.Capacity.TryGetValue(metric, out var capacity))
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{
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return double.PositiveInfinity;
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}
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var usageValue = usage.ToDouble();
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var capacityValue = capacity.ToDouble();
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if (capacityValue == 0)
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{
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return double.PositiveInfinity;
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}
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return usageValue / capacityValue;
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}
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/// <summary>
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/// Calculate the sum of a metric across all containers in a pod.
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/// </summary>
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private static double CalculatePodMetricSum(PodMetrics podMetrics, string metric)
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{
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if (podMetrics?.Containers == null)
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{
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return 0;
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}
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double sum = 0;
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foreach (var container in podMetrics.Containers)
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{
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if (container?.Usage != null && container.Usage.TryGetValue(metric, out var value))
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{
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sum += value.ToDouble();
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}
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}
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return sum;
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}
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}

‎src/KubernetesClient.Kubectl/Beta/Kubectl.Top.cs‎

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using k8s.Models;
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namespace k8s.kubectl.beta;
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public partial class Kubectl
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{
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/// <summary>
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/// Get top nodes sorted by CPU or memory usage.
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/// </summary>
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/// <param name="metric">The metric to sort by ("cpu" or "memory"). Defaults to "cpu".</param>
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/// <returns>A list of nodes with their metrics, sorted by the specified metric in descending order.</returns>
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public List<AsyncKubectl.ResourceMetrics<V1Node, NodeMetrics>> TopNodes(string metric = "cpu")
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{
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return client.TopNodesAsync(metric).GetAwaiter().GetResult();
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}
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/// <summary>
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/// Get top pods in a namespace sorted by CPU or memory usage.
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/// </summary>
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/// <param name="namespace">The namespace to get pod metrics from.</param>
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/// <param name="metric">The metric to sort by ("cpu" or "memory"). Defaults to "cpu".</param>
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/// <returns>A list of pods with their metrics, sorted by the specified metric in descending order.</returns>
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public List<AsyncKubectl.ResourceMetrics<V1Pod, PodMetrics>> TopPods(string @namespace, string metric = "cpu")
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{
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return client.TopPodsAsync(@namespace, metric).GetAwaiter().GetResult();
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}
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}

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