k6 Converter: Cannot unmarshal array into Go value of type map[string]interface {}

[san-slysz]

Hey everyone,

I'm using the .har converter, and on one files obtained an error message.

Step to reproduce

• Use my .har file
• Convert it (see the line I use below)

Convert line
san@computer:~/mypath$ k6 convert save.har -O save.js --enable-status-code-checks --correlate --no-batch (--skip url1 --skip url2...)

Error Message
ERRO[0000] json: cannot unmarshal array into Go value of type map[string]interface {}

File (.har)
The file is difficult to reduce (and still make it valid). And contains some data I'm not crazy to put here. So please contact me (I'm on k6 slack) to obtain it :).

[na--]

@san-ouadghiri sent me a sample file that triggered this and the issue is a wrong assumption in the k6 HAR converter. Here's a pared-down and edited version of the problematic HAR file:

{
  "log": {
    "version": "1.1",
    "creator": {
      "name": "Firefox",
      "version": "62.0"
    },
    "browser": {
      "name": "Firefox",
      "version": "62.0"
    },
    "pages": [
      {
        "startedDateTime": "2018-09-24T10:57:17.234+02:00",
        "id": "page_3",
        "title": "sample page",
        "pageTimings": {
          "onContentLoad": -1,
          "onLoad": -1
        }
      }
    ],
    "entries": [
      {
        "pageref": "page_3",
        "startedDateTime": "2018-09-24T10:57:17.234+02:00",
        "request": {
          "bodySize": 2,
          "method": "PATCH",
          "url": "https://httpbin.org/anything",
          "httpVersion": "HTTP/2.0",
          "headers": [
            {
              "name": "content-type",
              "value": "application/json"
            }
          ],
          "queryString": [],
          "postData": {
            "mimeType": "application/json",
            "params": [],
            "text": "[]"
          }
        },
        "response": {
          "status": 200,
          "statusText": "OK",
          "httpVersion": "HTTP/2.0",
          "headers": [
            {
              "name": "content-type",
              "value": "application/json; charset=utf-8"
            }
          ],
          "cookies": [],
          "content": {
            "mimeType": "application/json; charset=utf-8",
            "size": 2,
            "text": "{}"
          },
          "redirectURL": "",
          "headersSize": 566,
          "bodySize": 2
        },
        "cache": {},
        "timings": {
          "blocked": 0,
          "dns": 0,
          "connect": 0,
          "ssl": 0,
          "send": 0,
          "wait": 811,
          "receive": 0
        },
        "time": 811,
        "_securityState": "secure",
        "connection": "443"
      }
    ]
  }
}

The problem comes from the "text": "[]" in postData - k6 attempts to json.Unmarshal() that into a map[string]interface{} variable and predictably fails.

@san-ouadghiri - disabling --correlate will work around the issue for now. I have to delve deeper into the correlation logic to understand the rationale behind the current code, but fixing the issue may just involve ignoring any cases that don't fit the current narrow correlation logic...

[san-slysz]

Thanks! Good luck with your fix-expedition. In the meanwhile I'll use the given workaround :).

[codebien]

The k6 convert command has been deprecated and will be removed in the future #3365.

Use https://github.com/grafana/har-to-k6 as a better alternative.