function _M.rewrite()

in apisix/plugins/zipkin.lua [127:244]

• 92 lines of code
• 12 McCabe index (conditional complexity)

function _M.rewrite(plugin_conf, ctx)
    local conf = core.table.clone(plugin_conf)
    
    conf.server_port = tonumber(ctx.var['server_port'])

    if not conf.server_addr or conf.server_addr == '' then
        conf.server_addr = ctx.var["server_addr"]
    end

    local tracer = core.lrucache.plugin_ctx(lrucache, ctx, conf.server_addr .. conf.server_port,
                                            create_tracer, conf, ctx)

    local headers = core.request.headers(ctx)
    local per_req_sample_ratio

    
    
    local debug = headers["x-b3-flags"]
    if debug == "1" then
        per_req_sample_ratio = 1
    end

    local trace_id, request_span_id, sampled, parent_span_id
    local b3 = headers["b3"]
    if b3 then
        
        
        
        core.request.set_header(ctx, "b3", nil)

        local err
        err, trace_id, request_span_id, sampled, parent_span_id = parse_b3(b3)

        if err then
            core.log.error("invalid b3 header: ", b3, ", ignored: ", err)
            return 400
        end

        if sampled == "d" then
            core.request.set_header(ctx, "x-b3-flags", "1")
            sampled = "1"
        end
    else
        
        sampled = headers["x-b3-sampled"]
        trace_id = headers["x-b3-traceid"]
        parent_span_id = headers["x-b3-parentspanid"]
        request_span_id = headers["x-b3-spanid"]
    end

    local zipkin_ctx = core.tablepool.fetch("zipkin_ctx", 0, 3)
    zipkin_ctx.trace_id = trace_id
    zipkin_ctx.parent_span_id = parent_span_id
    zipkin_ctx.request_span_id = request_span_id
    ctx.zipkin = zipkin_ctx

    local wire_context = tracer:extract("http_headers", ctx)

    local start_timestamp = ngx.req.start_time()
    local request_span = tracer:start_span("apisix.request", {
        child_of = wire_context,
        start_timestamp = start_timestamp,
        tags = {
            component = "apisix",
            ["span.kind"] = "server",
            ["http.method"] = ctx.var.request_method,
            ["http.url"] = ctx.var.request_uri,
             
            ["peer.ipv4"] = core.request.get_remote_client_ip(ctx),
            ["peer.port"] = core.request.get_remote_client_port(ctx),
        }
    })

    ctx.opentracing = {
        tracer = tracer,
        wire_context = wire_context,
        request_span = request_span,
    }

    
    if sampled == "1" or sampled == "true" then
        per_req_sample_ratio = 1
    elseif sampled == "0" or sampled == "false" then
        per_req_sample_ratio = 0
    end

    ctx.opentracing_sample = tracer.sampler:sample(per_req_sample_ratio or conf.sample_ratio)
    if not ctx.opentracing_sample then
        request_span:set_baggage_item("x-b3-sampled","0")
    else
       request_span:set_baggage_item("x-b3-sampled","1")
    end

    if plugin_info.set_ngx_var then
        local span_context = request_span:context()
        ngx_var.zipkin_context_traceparent = string_format("00-%s-%s-%02x",
                                             to_hex(span_context.trace_id),
                                             to_hex(span_context.span_id),
                                             span_context:get_baggage_item("x-b3-sampled"))
        ngx_var.zipkin_trace_id = span_context.trace_id
        ngx_var.zipkin_span_id = span_context.span_id
    end

    if not ctx.opentracing_sample then
        return
    end

    local request_span = ctx.opentracing.request_span
    if conf.span_version == ZIPKIN_SPAN_VER_1 then
        ctx.opentracing.rewrite_span = request_span:start_child_span("apisix.rewrite",
                                                                     start_timestamp)
        ctx.REWRITE_END_TIME = tracer:time()
        ctx.opentracing.rewrite_span:finish(ctx.REWRITE_END_TIME)
    else
        ctx.opentracing.proxy_span = request_span:start_child_span("apisix.proxy",
                                                                   start_timestamp)
    end
end