[GitHub] [apisix] kingluo commented on issue #7674: help request: opentelemetry error in lua script

[GitBox <gi...@apache.org>]

kingluo commented on issue #7674:
URL: https://github.com/apache/apisix/issues/7674#issuecomment-1216450883

   @akalittle The `hex2bytes` assumes the input string is in valid hex format (`[0-9a-f]{32}`), and transforms each hex u8 number into char. The `char()` assumes the number ranges from 0~255, otherwise it would throw error.
   It's likely your `span.ctx.trace_id` (https://github.com/yangxikun/opentelemetry-lua/blob/v0.1.3/lib/opentelemetry/trace/exporter/otlp.lua#L50) contains `-`, which means negative number and cause `char()` failed. It means your trace id comes from `x-request-id` in invalid format.
   
   ```lua
   local function hex2bytes(str)
       return (str:gsub('..', function (cc)
           local n = tonumber(cc, 16)
           if n then
               print(n)
               return string.char(n)
           end
       end))
   end
   
   hex2bytes("xx-1")
   ```
   
   ```
   /usr/local/openresty-debug/luajit/bin/luajit: bad argument #1 to '?' (invalid value)
   stack traceback:
           [builtin#80]: at 0x5571dae60530
           [C]: in function 'gsub'
           /tmp/test_gsub.lua:2: in function 'hex2bytes'
           /tmp/test_gsub.lua:11: in main chunk
           [C]: at 0x5571dadfc320
   
   ```
   


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