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Adding back PrometheusHandler to avoid breaking change (#1534)
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using System.Diagnostics; | ||
using System.Diagnostics.Metrics; | ||
using System.Net.Http; | ||
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namespace k8s | ||
{ | ||
/// <summary> | ||
/// Implements legacy Prometheus metrics | ||
/// </summary> | ||
/// <remarks>Provided for compatibility for existing usages of PrometheusHandler. It is recommended | ||
/// to transition to using OpenTelemetry and the default HttpClient metrics. | ||
/// | ||
/// Note that the tags/labels are not appropriately named for some metrics. This | ||
/// incorrect naming is retained to maintain compatibility and won't be fixed on this implementation. | ||
/// Use OpenTelemetry and the standard HttpClient metrics instead.</remarks> | ||
public class PrometheusHandler : DelegatingHandler | ||
{ | ||
private const string Prefix = "k8s_dotnet"; | ||
private static readonly Meter Meter = new Meter("k8s.dotnet"); | ||
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private static readonly Counter<int> RequestsSent = Meter.CreateCounter<int>( | ||
$"{Prefix}_request_total", | ||
description: "Number of requests sent by this client"); | ||
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private static readonly Histogram<double> RequestLatency = Meter.CreateHistogram<double>( | ||
$"{Prefix}_request_latency_seconds", unit: "milliseconds", | ||
description: "Latency of requests sent by this client"); | ||
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private static readonly Counter<int> ResponseCodes = Meter.CreateCounter<int>( | ||
$"{Prefix}_response_code_total", | ||
description: "Number of response codes received by the client"); | ||
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private static readonly UpDownCounter<int> ActiveRequests = | ||
Meter.CreateUpDownCounter<int>( | ||
$"{Prefix}_active_requests", | ||
description: "Number of requests currently in progress"); | ||
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/// <inheritdoc /> | ||
protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken) | ||
{ | ||
if (request == null) | ||
{ | ||
throw new ArgumentNullException(nameof(request)); | ||
} | ||
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var digest = KubernetesRequestDigest.Parse(request); | ||
var timer = Stopwatch.StartNew(); | ||
// Note that this is a tag called "method" but the value is the Verb. | ||
// This is incorrect, but existing behavior. | ||
var methodWithVerbValue = new KeyValuePair<string, object>("method", digest.Verb); | ||
try | ||
{ | ||
ActiveRequests.Add(1, methodWithVerbValue); | ||
RequestsSent.Add(1, methodWithVerbValue); | ||
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var resp = await base.SendAsync(request, cancellationToken).ConfigureAwait(false); | ||
ResponseCodes.Add( | ||
1, | ||
new KeyValuePair<string, object>("method", request.Method.ToString()), | ||
new KeyValuePair<string, object>("code", (int)resp.StatusCode)); | ||
return resp; | ||
} | ||
finally | ||
{ | ||
timer.Stop(); | ||
ActiveRequests.Add(-1, methodWithVerbValue); | ||
var tags = new TagList | ||
{ | ||
{ "verb", digest.Verb }, | ||
{ "group", digest.ApiGroup }, | ||
{ "version", digest.ApiVersion }, | ||
{ "kind", digest.Kind }, | ||
} | ||
; | ||
RequestLatency.Record(timer.Elapsed.TotalMilliseconds, tags); | ||
} | ||
} | ||
} | ||
} |