http {
    lua_package_path "/Path/to/.../skywalking-nginx-lua/lib/?.lua;;";

    # Buffer represents the register inform and the queue of the finished segment
    lua_shared_dict tracing_buffer 100m;

    # Init is the timer setter and keeper
    # Setup an infinite loop timer to do register and trace report.
    init_worker_by_lua_block {
        local metadata_buffer = ngx.shared.tracing_buffer

        -- Set service name
        metadata_buffer:set('serviceName', 'User Service Name')
        -- Instance means the number of Nginx deployment, does not mean the worker instances
        metadata_buffer:set('serviceInstanceName', 'User Service Instance Name')
        -- type 'boolean', mark the entrySpan include host/domain
        metadata_buffer:set('includeHostInEntrySpan', false)
        -- set ignoreSuffix, If the operation name(HTTP URI) of the entry span includes suffixes in this set, this segment would be ignored. Multiple values should be separated by a comma(',').
        -- require("skywalking.util").set_ignore_suffix(".jpg,.jpeg,.js,.css,.png,.bmp,.gif,.ico,.mp3,.mp4,.svg")

        -- set random seed
        require("skywalking.util").set_randomseed()
        require("skywalking.client"):startBackendTimer("http://127.0.0.1:8080")

        -- If there is a bug of this `tablepool` implementation, we can
        -- disable it in this way
        -- require("skywalking.util").disable_tablepool()

        skywalking_tracer = require("skywalking.tracer")
    }

    server {
        listen 8090;
        
        location /ingress {
            default_type text/html;

            rewrite_by_lua_block {
                ------------------------------------------------------
                -- NOTICE, this should be changed manually
                -- This variable represents the upstream logic address
                -- Please set them as service logic name or DNS name
                --
                -- Currently, we can not have the upstream real network address
                ------------------------------------------------------
                skywalking_tracer:start("upstream service")
                -- If you want correlation custom data to the downstream service
                -- skywalking_tracer:start("upstream service", {custom = "custom_value"})
            }

            -- Target upstream service
            proxy_pass http://127.0.0.1:8080/backend;

            body_filter_by_lua_block {
                if ngx.arg[2] then
                    skywalking_tracer:finish()
                end
            }

            log_by_lua_block {
                skywalking_tracer:prepareForReport()
            }
        }
    }
}

2020/04/04 15:15:37 [debug] 12089#1446111: *4 [lua] content_by_lua(nginx.conf:175):4: Instance report request = {"service":"User Service Name","serviceInstance":"User Service Instance Name","properties":[{"language":"Lua"}]}
2020/04/04 15:15:37 [debug] 12089#1446111: *2 [lua] client.lua:89: reportServiceInstance(): Instance report response = {}

2020/04/04 15:15:40 [debug] 12089#1446111: *4 [lua] content_by_lua(nginx.conf:188):3: KeepAlive request = {"service":"User Service Name","serviceInstance":"User Service Instance Name"}

2020/04/04 15:15:46 [debug] 12089#1446111: *11 [lua] tracer.lua:83: prepareForReport(): segment = {"traceId":"1585984546953.410917649.45972","serviceInstance":"User Service Instance Name","spans":[{"operationName":"\/tier2\/lb","startTime":1585984546967,"endTime":1585984546968,"spanType":"Exit","spanId":1,"isError":false,"parentSpanId":0,"componentId":6000,"peer":"backend service","spanLayer":"Http"},{"operationName":"\/tier2\/lb","startTime":1585984546967,"tags":[{"key":"http.method","value":"GET"},{"key":"http.params","value":"http:\/\/127.0.0.1\/tier2\/lb"}],"endTime":1585984546968,"spanType":"Entry","spanId":0,"isError":false,"parentSpanId":-1,"componentId":6000,"refs":[{"traceId":"1585984546953.410917649.45972","networkAddressUsedAtPeer":"upstream service","parentEndpoint":"\/ingress","parentServiceInstance":"User Service Instance Name","parentSpanId":1,"parentService":"User Service Name","parentTraceSegmentId":"1585984546953.410917649.45972","refType":"CrossProcess"}],"spanLayer":"Http"}],"service":"User Service Name","traceSegmentId":"1585984546967.449397702.9959"}
2020/04/04 15:15:46 [debug] 12089#1446111: *11 [lua] tracer.lua:87: prepareForReport(): segment buffer size = 1
2020/04/04 15:15:46 [debug] 12089#1446111: *8 [lua] tracer.lua:83: prepareForReport(): segment = {"traceId":"1585984546953.410917649.45972","serviceInstance":"User Service Instance Name","spans":[{"operationName":"\/ingress","startTime":1585984546953,"endTime":1585984546968,"spanType":"Exit","spanId":1,"isError":false,"parentSpanId":0,"componentId":6000,"peer":"upstream service","spanLayer":"Http"},{"operationName":"\/ingress","startTime":1585984546953,"tags":[{"key":"http.method","value":"GET"},{"key":"http.params","value":"http:\/\/localhost\/ingress"}],"endTime":1585984546968,"spanType":"Entry","spanId":0,"parentSpanId":-1,"isError":false,"spanLayer":"Http","componentId":6000}],"service":"User Service Name","traceSegmentId":"1585984546953.410917649.45972"}