Java 使用 Istio 进行微服务分布式跟踪

Question

集群中已经安装了 Kubernetes 和 Istio。三个微服务部署为 PODs。流量是

Micro service A to Micro Service B calls => HTTP
Micro service B to Micro service C calls => via Kafka
Micro service A expose a HTTP API to outside

我猜当客户端点击 Ingres 时，Istio 在 HTTP header 中生成 traceId 和 spanId 并进入服务 A。这些 spanId 和 traceId 是否传播到微服务 B 和 C，而不使用像 Spring Cloud sleuth 这样的单独 API？

Answer 1

不，Istio 不提供跟踪 headers 传播。但是，它可以在应用程序端进行配置，而无需使用 3rd 方 API。

根据 Istio 文档：

Istio leverages Envoy’s distributed tracing feature to provide tracing integration out of the box. Specifically, Istio provides options to install various tracing backend and configure proxies to send trace spans to them automatically. See Zipkin, Jaeger and LightStep task docs about how Istio works with those tracing systems.

Istio 文档还有一个 example 应用程序端 header 用于 bookinfo 演示应用程序的传播：

Trace context propagation

Although Istio proxies are able to automatically send spans, they need some hints to tie together the entire trace. Applications need to propagate the appropriate HTTP headers so that when the proxies send span information, the spans can be correlated correctly into a single trace.

To do this, an application needs to collect and propagate the following headers from the incoming request to any outgoing requests:

x-request-id

x-b3-traceid

x-b3-spanid

x-b3-parentspanid

x-b3-sampled

x-b3-flags

x-ot-span-context

Additionally, tracing integrations based on OpenCensus (e.g. Stackdriver) propagate the following headers:

x-cloud-trace-context

traceparent

grpc-trace-bin

If you look at the sample Python productpage service, for example, you see that the application extracts the required headers from an HTTP request using OpenTracing libraries:

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

The reviews application (Java) does something similar:

@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);

When you make downstream calls in your applications, make sure to include these headers.

Java 使用 Istio 进行微服务分布式跟踪

Java micro service distributed tracing with Istio

spring-cloud-sleuth

istio

Trace context propagation