/// <summary>
/// Gets the accessor used to retreive a correlation id from an <see cref="HttpContext"/>.
/// </summary>
/// <param name="httpContext">The http context.</param>
/// <returns>The correlation id accessor.</returns>
/// <param name="correlationIdHeader">The name of the correlation id header.</param>
public static ICorrelationIdAccessor GetCorrelationIdAccessor(this HttpContext httpContext, string correlationIdHeader = CorrelationId)
{
if (httpContext is null)
{
throw new ArgumentNullException(nameof(httpContext));
}
if (correlationIdHeader is null)
{
throw new ArgumentNullException(nameof(correlationIdHeader));
}
if (!httpContext.Items.TryGetValue(typeof(ICorrelationIdAccessor), out var value) ||
!(value is ICorrelationIdAccessor accessor))
{
accessor = new CorrelationIdAccessor();
if (httpContext.GetHeaderValue(correlationIdHeader) is StringValues correlationId && correlationId.Count > 0)
{
accessor.CorrelationId = correlationId;
}
// lean on OpenTelemetry for an existing traceId
if (accessor.CorrelationId is null)
{
accessor.CorrelationId = Tracer.CurrentSpan?.Context.TraceId.ToString();
}
// fallback to creating a new value
if (accessor.CorrelationId is null)
{
accessor.CorrelationId = Guid.NewGuid().ToString();
}
httpContext.Items[typeof(ICorrelationIdAccessor)] = accessor;
}
return(accessor);
}
public CorrelationIdAccessorTests()
{
_underTest = new CorrelationIdAccessor();
}