在ASM中实现分布式跟踪

在按照部署应用到ASM实例进行应用部署之后，查看示例中以Python语言实现的productpage服务，则会发现该应用程序使用了OpenTracing库从HTTP请求中提取了所需的标头。

def getForwardHeaders(request):
    headers = {}

    # x-b3-*** headers can be populated using the opentracing span
    span = get_current_span()
    carrier = {}
    tracer.inject(
        span_context=span.context,
        format=Format.HTTP_HEADERS,
        carrier=carrier)

    headers.update(carrier)

    # ...

    incoming_headers = ['x-request-id']

    # ...

    for ihdr in incoming_headers:
        val = request.headers.get(ihdr)
        if val is not None:
            headers[ihdr] = val

    return headers

查看以Java语言实现的reviews服务是也可以看到相应的HTTP标头。

@GET
@Path("/reviews/{productId}")
public Response bookReviewsById(@PathParam("productId") int productId,
                            @HeaderParam("end-user") String user,
                            @HeaderParam("x-request-id") String xreq,
                            @HeaderParam("x-b3-traceid") String xtraceid,
                            @HeaderParam("x-b3-spanid") String xspanid,
                            @HeaderParam("x-b3-parentspanid") String xparentspanid,
                            @HeaderParam("x-b3-sampled") String xsampled,
                            @HeaderParam("x-b3-flags") String xflags,
                            @HeaderParam("x-ot-span-context") String xotspan) {

  if (ratings_enabled) {
    JsonObject ratingsResponse = getRatings(Integer.toString(productId), user, xreq, xtraceid, xspanid, xparentspanid, xsampled, xflags, xotspan);