| | | 1 | | using System.Diagnostics; |
| | | 2 | | |
| | | 3 | | namespace ArturRios.Util.WebApi.Handlers; |
| | | 4 | | |
| | | 5 | | /// <summary> |
| | | 6 | | /// Propagates the W3C traceparent header on outgoing HttpClient requests. |
| | | 7 | | /// Register this as an HttpMessageHandler for typed/named HttpClients. |
| | | 8 | | /// </summary> |
| | | 9 | | public class TracePropagationHandler : DelegatingHandler |
| | | 10 | | { |
| | | 11 | | private const string TraceParentHeader = "traceparent"; |
| | | 12 | | |
| | | 13 | | /// <summary>Adds the current <see cref="Activity"/>'s W3C <c>traceparent</c> header to the outgoing |
| | | 14 | | /// request, if one isn't already present, before delegating to the inner handler.</summary> |
| | | 15 | | /// <param name="request">The outgoing HTTP request.</param> |
| | | 16 | | /// <param name="cancellationToken">A token to cancel the send operation.</param> |
| | | 17 | | protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, |
| | | 18 | | CancellationToken cancellationToken) |
| | 0 | 19 | | { |
| | 0 | 20 | | var activity = Activity.Current; |
| | | 21 | | |
| | 0 | 22 | | if (activity is null) |
| | 0 | 23 | | { |
| | 0 | 24 | | return base.SendAsync(request, cancellationToken); |
| | | 25 | | } |
| | | 26 | | |
| | 0 | 27 | | var traceParent = $"00-{activity.TraceId}-{activity.SpanId}-{(activity.Recorded ? "01" : "00")}"; |
| | | 28 | | |
| | 0 | 29 | | if (!request.Headers.Contains(TraceParentHeader)) |
| | 0 | 30 | | { |
| | 0 | 31 | | request.Headers.Add(TraceParentHeader, traceParent); |
| | 0 | 32 | | } |
| | | 33 | | |
| | 0 | 34 | | return base.SendAsync(request, cancellationToken); |
| | 0 | 35 | | } |
| | | 36 | | } |