in lib/skywalking/tracing_context.lua [162:175]
function _M.inject(tracingContext, exitSpan, peer, correlation)
Span.setPeer(exitSpan, peer)
local injectableRef = SegmentRef.createInjectableRef(tracingContext, exitSpan)
local correlationData = tracingContext.correlation
if correlation then
for name, value in pairs(correlation) do
CorrelationContext.put(correlationData, name, value)
end
end
ngx.req.set_header(CONTEXT_CARRIER_KEY, SegmentRef.serialize(injectableRef))
ngx.req.set_header(CONTEXT_CORRELATION_KEY, CorrelationContext.serialize(correlationData))
end