Use Xray sdk in Lambda to send segments over UDP

Question

I am using Lambda. I want to send a subsegment to Xray with an custom end_time. Xray is enabled in my Lambda.

When I use the aws-xray-sdk-core and addNewSubsegment('postgres') I do not find the possibility to add an end_time. It looks like the end_time is being set when you close() the Segment.

To try and solve this limitation I base myself on the following to send a custom segment to the Xray Daemon using UDP. Use UDP to send segment to XRay

Below code is not sending a SubSegment to Xray. I am not receiving any errors when sending the segment with client.send(...).

Does someone knows more about this limitation of setting an custom end_time/ knows if it's possible with UDP inside a Lambda?

      import AWSXRay from 'aws-xray-sdk-core'
      const traceDocument = {
        trace_id,
        id: generateRandomHex(16),
        name: 'postgres',
        start_time,
        end_time,
        type: 'subsegment',
        parent_id,
        sql: { sanitized_query: query },
      }

      const client = createSocket('udp4')

      const udpSegment = `{"format": "json", "version": 1}\n${traceDocument}`

      client.send(udpSegment, 2000, '127.0.0.1', (e, b) => {
        console.log(e, b)
      })

I'm currently trying out the flush() command which seems to send the subsegment without setting the end_time. Lets say the documentation is scarce and I had to look into the sdk itself to figure out what was happening. — Lucasz

Lucasz Lucasz · Accepted Answer · 2021-09-23T17:16:31

Managed to find out the solution myself

used the X-Ray SDK with a combination of

addAttribute('in_progress', false) and streamSubsegments() to send the subsegments to X-Ray

export const onQueryEvent = async (e) => {
  try {
   const segment = AWSXRay.getSegment()
     if (segment) {    
      const paramsArr = JSON.parse(e.params)
      const query = getQueryWithParams(e.query, paramsArr)      // X-Ray wants the time in seconds -> ms * 1e-3
      const start_time = e.timestamp.valueOf() * 1e-3 
      const end_time = (e.timestamp.valueOf() + e.duration) * 1e-3
     
      // Add a new Subsegment to parent Segment
      const subSegment = segment.addNewSubsegment('postgres')      // Add data to the segment
      subSegment.addSqlData({ sanitized_query: query })
      subSegment.addAttribute('start_time', start_time)
      subSegment.addAttribute('end_time', end_time)      // Set in_progress to false so subSegment 
      // will be send to xray on streamSubsegments()
      subSegment.addAttribute('in_progress', false)
      subSegment.streamSubsegments()
     }
  } catch (e) {
  console.log(e)
  }
}

Use Xray sdk in Lambda to send segments over UDP

1 Answers