CD
Cloudflare Developers•2mo ago
SakuraFC

Worker Logging, Bytes Sent

I am trying to troubleshoot a worker and need to know how many bytes was sent for each request, especially when the request is canceled by the client. I am trying to implement some debugging g logging in hono middleware, and cannot find a way to either get the info from Cloudflare, or make some sort of “proxy” stream to capture bytes read before client disconnects. I tried going with TransformStream as intermediary, but get “Body has already been used. It can only be used once. Use tee() first if you need to read it twice.” exception. Any advice how to know per request bytes sent in hono worker?
1 Reply
DaniFoldi
DaniFoldi•2mo ago
You should be able to find the number of bytes in the content-length header, and if compressed, the number of bytes transmitted in the transfer-length header for the request. Although if you don't trust the values, for debugging, here's a script that should (I'm just writing it here on discord, so some minor issues might need to be fixed) 
export default {
  async fetch(request, env, ctx) {
    let requestSize = 0
    if (request.body) {
      const requestClone = request.clone()
      const reader = requestClone.body.getReader()
      while (true) {
        const { done, value } = await reader.read()
        if (done) break
        requestSize += value.length
      }
    }
    console.log(`Request Body Size: ${requestSize} bytes`)
    
    // Call your hono worker here
    const response = await app.fetch(request, env, ctx)
    
    let responseSize = 0
    const responseClone = response.clone()
    const reader = responseClone.body.getReader()
    while (true) {
      const { done, value } = await reader.read()
      if (done) break
      responseSize += value.length
    }
    console.log(`Response Body Size: ${responseSize} bytes`)
    
    return response
  }
} satisfies ExportedHandler
export default {
  async fetch(request, env, ctx) {
    let requestSize = 0
    if (request.body) {
      const requestClone = request.clone()
      const reader = requestClone.body.getReader()
      while (true) {
        const { done, value } = await reader.read()
        if (done) break
        requestSize += value.length
      }
    }
    console.log(`Request Body Size: ${requestSize} bytes`)
    
    // Call your hono worker here
    const response = await app.fetch(request, env, ctx)
    
    let responseSize = 0
    const responseClone = response.clone()
    const reader = responseClone.body.getReader()
    while (true) {
      const { done, value } = await reader.read()
      if (done) break
      responseSize += value.length
    }
    console.log(`Response Body Size: ${responseSize} bytes`)
    
    return response
  }
} satisfies ExportedHandler
Ps. instead of tee()-ing, I cloned them, but it's basically the same, just with a less confusing syntax Hope this helps!

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