| | | 1 | | // Copyright (c) ZeroC, Inc. |
| | | 2 | | |
| | | 3 | | using IceRpc.Extensions.DependencyInjection; |
| | | 4 | | using System.Buffers; |
| | | 5 | | using System.Diagnostics; |
| | | 6 | | using ZeroC.Slice.Codec; |
| | | 7 | | |
| | | 8 | | namespace IceRpc.Telemetry; |
| | | 9 | | |
| | | 10 | | /// <summary>A middleware that starts an <see cref="Activity" /> per request, following |
| | | 11 | | /// <see href="https://opentelemetry.io/">OpenTelemetry</see> conventions. The middleware restores the parent invocation |
| | | 12 | | /// activity from the request <see cref="RequestFieldKey.TraceContext" /> field before starting the dispatch activity. |
| | | 13 | | /// </summary> |
| | | 14 | | /// <remarks>The activities are only created for requests using the icerpc protocol.</remarks> |
| | | 15 | | /// <seealso cref="TelemetryRouterExtensions" /> |
| | | 16 | | /// <seealso cref="TelemetryDispatcherBuilderExtensions"/> |
| | | 17 | | public class TelemetryMiddleware : IDispatcher |
| | | 18 | | { |
| | | 19 | | private readonly IDispatcher _next; |
| | | 20 | | private readonly ActivitySource _activitySource; |
| | | 21 | | |
| | | 22 | | /// <summary>Constructs a telemetry middleware.</summary> |
| | | 23 | | /// <param name="next">The next dispatcher in the dispatch pipeline.</param> |
| | | 24 | | /// <param name="activitySource">The <see cref="ActivitySource" /> is used to start the request activity.</param> |
| | 8 | 25 | | public TelemetryMiddleware(IDispatcher next, ActivitySource activitySource) |
| | 8 | 26 | | { |
| | 8 | 27 | | _next = next; |
| | 8 | 28 | | _activitySource = activitySource; |
| | 8 | 29 | | } |
| | | 30 | | |
| | | 31 | | /// <inheritdoc/> |
| | | 32 | | public async ValueTask<OutgoingResponse> DispatchAsync(IncomingRequest request, CancellationToken cancellationToken) |
| | 8 | 33 | | { |
| | 8 | 34 | | if (request.Protocol.HasFields) |
| | 8 | 35 | | { |
| | 8 | 36 | | string name = $"{request.Path}/{request.Operation}"; |
| | 8 | 37 | | using Activity activity = _activitySource.CreateActivity(name, ActivityKind.Server) ?? new Activity(name); |
| | 8 | 38 | | activity.AddTag("rpc.system", "icerpc"); |
| | 8 | 39 | | activity.AddTag("rpc.service", request.Path); |
| | 8 | 40 | | activity.AddTag("rpc.method", request.Operation); |
| | 8 | 41 | | if (request.Fields.TryGetValue(RequestFieldKey.TraceContext, out ReadOnlySequence<byte> buffer)) |
| | 7 | 42 | | { |
| | 7 | 43 | | RestoreActivityContext(buffer, activity); |
| | 6 | 44 | | } |
| | 7 | 45 | | activity.Start(); |
| | 7 | 46 | | return await _next.DispatchAsync(request, cancellationToken).ConfigureAwait(false); |
| | | 47 | | } |
| | | 48 | | else |
| | 0 | 49 | | { |
| | 0 | 50 | | return await _next.DispatchAsync(request, cancellationToken).ConfigureAwait(false); |
| | | 51 | | } |
| | 7 | 52 | | } |
| | | 53 | | |
| | | 54 | | internal static void RestoreActivityContext(ReadOnlySequence<byte> buffer, Activity activity) |
| | 10 | 55 | | { |
| | 10 | 56 | | var decoder = new SliceDecoder(buffer); |
| | | 57 | | |
| | | 58 | | // Read W3C traceparent binary encoding (1 byte version, 16 bytes trace-ID, 8 bytes span-ID, |
| | | 59 | | // 1 byte flags) https://www.w3.org/TR/trace-context/#traceparent-header-field-values |
| | | 60 | | |
| | 10 | 61 | | byte traceIdVersion = decoder.DecodeUInt8(); |
| | | 62 | | |
| | 9 | 63 | | using IMemoryOwner<byte> memoryOwner = MemoryPool<byte>.Shared.Rent(16); |
| | 9 | 64 | | Span<byte> traceIdSpan = memoryOwner.Memory.Span[0..16]; |
| | 9 | 65 | | decoder.CopyTo(traceIdSpan); |
| | 9 | 66 | | var traceId = ActivityTraceId.CreateFromBytes(traceIdSpan); |
| | | 67 | | |
| | 9 | 68 | | Span<byte> spanIdSpan = memoryOwner.Memory.Span[0..8]; |
| | 9 | 69 | | decoder.CopyTo(spanIdSpan); |
| | 9 | 70 | | var spanId = ActivitySpanId.CreateFromBytes(spanIdSpan); |
| | | 71 | | |
| | 9 | 72 | | var traceFlags = (ActivityTraceFlags)decoder.DecodeUInt8(); |
| | | 73 | | |
| | 9 | 74 | | activity.SetParentId(traceId, spanId, traceFlags); |
| | | 75 | | |
| | | 76 | | // Read TraceState encoded as a string |
| | 9 | 77 | | activity.TraceStateString = decoder.DecodeString(); |
| | | 78 | | |
| | | 79 | | // Decode the baggage sequence, silently clipping to MaxBaggageEntries. OpenTelemetry SDKs |
| | | 80 | | // follow a strict no-throw policy for observability operations: losing a piece of contextual |
| | | 81 | | // metadata is less damaging than failing the RPC, and silent clipping matches the behavior of |
| | | 82 | | // OpenTelemetry .NET's and Python's BaggagePropagator on incoming headers. Only the first |
| | | 83 | | // MaxBaggageEntries entries are read from the buffer; the remainder is left unconsumed. |
| | | 84 | | // |
| | | 85 | | // Activity.Baggage's enumeration order is undocumented, so duplicate-key resolution across the |
| | | 86 | | // wire is inherently undefined on both ends — we don't attempt to preserve it. |
| | 9 | 87 | | int count = decoder.DecodeSize(); |
| | 9 | 88 | | int kept = Math.Min(count, TelemetryInterceptor.MaxBaggageEntries); |
| | | 89 | | |
| | 598 | 90 | | for (int i = 0; i < kept; i++) |
| | 290 | 91 | | { |
| | 290 | 92 | | string key = decoder.DecodeString(); |
| | 290 | 93 | | string value = decoder.DecodeString(); |
| | 290 | 94 | | activity.AddBaggage(key, value); |
| | 290 | 95 | | } |
| | 18 | 96 | | } |
| | | 97 | | } |