K6 script is not sending requests/ Postman missing HTTP Headers

[thim81]

I have converted a Postman collection to K6 scripts, but the when running K6 to execute the K6 scripts k6 run k6-scripts.js nothing is happing OR errors are shown OR my API service did not received any requests.

[thim81]

When you run K6, you can add a debug option

k6 run --http-debug="full k6-script.js

This will give you some insights into the actual HTTP requests being made.

Common issues

Common issues to review:

• A header might be missing
• The API URL/host is not present because some Postman Variables are not set

Missing headers

A missing HTTP header can have a big impact on how your API reacts to requests like authentication header or content-type, so it is important that HTTP headers are included in the K6 requests.

Some explanation:

• Postman does not explicitly set common "headers", like content-type/accept (see github) when exporting the Postman collection.
• postman-to-k6 takes the Postman collection as the source and converts the JSON Postman collection into K6, so if the Postman collection JSON has no content-type set, the Content-Type header will not be part of the K6 requests.
• K6 uses by default uses application/x-www-form-urlencoded if no content-type header is set.

Possible solutions:

• Set the desired header explicitly in Postman, so that it is part of the Postman collection when exported
• Manually add the K6 params options
• Pass it postman-to-k6 using the --k6-params

An example of a "k6-params.json":

{
  "maxRedirects": 6,
  "headers": {
    "Content-Type": "application/json"
  }
}

And then use it like this when converting your postman collection to K6 scripts.

postman-to-k6 collection.json --k6-params k6-params.json -o k6-script.js

Missing variables

In Postman you can use "variables" to define values, even on several levels: Globally (applicable for the complete collection), Environment (variables defined per environment, so that you can easily swap between a DEV & PROD API setup).

To pass Postman variables to the K6 scripts, you can have them injected during conversion:

• Global Variables
• Environment Variables

You can export your Environment variables from Postman and use the locally saved JSON file (ex: environment.json) with the Postman variables when converting from postman-to-k6.

postman-to-k6 collection.json --environment environment.json -o k6-script.js

Example of an exported Postman environment enviroment.js:

{
	"id": "c5a7595b-2001-4482-bae3-c7db15705a8e",
	"name": "K6 Office Hours",
	"values": [
		{
			"key": "USERNAME",
			"value": "test@example.com",
			"enabled": true
		},
		{
			"key": "PASSWORD",
			"value": "superCroc2020",
			"enabled": true
		},
		{
			"key": "FIRSTNAME",
			"value": "John",
			"enabled": true
		},
		{
			"key": "LASTNAME",
			"value": "Doe",
			"enabled": true
		},
		{
			"key": "EMAIL",
			"value": "test@example.com",
			"enabled": true
		},
		{
			"key": "ACCESS",
			"value": null,
			"enabled": true
		},
		{
			"key": "REFRESH",
			"value": null,
			"enabled": true
		},
		{
			"key": "CROCID",
			"value": null,
			"enabled": true
		},
		{
			"key": "baseUrl",
			"value": "http://localhost:3000",
			"type": "default",
			"enabled": true
		}
	],
	"_postman_variable_scope": "environment",
	"_postman_exported_at": "2022-02-24T12:07:22.073Z",
	"_postman_exported_using": "Postman/9.13.2"
}

which result in:

// Auto-generated by the postman-to-k6 converter

import "./libs/shim/core.js";
import { group } from "k6";

export let options = { maxRedirects: 4};

const Request = Symbol.for("request");
postman[Symbol.for("initial")]({
  options,
  collection: {
    baseUrl: "http://localhost:3000"
  },
  environment: {
    USERNAME: "test@example.com",
    PASSWORD: "superCroc2020",
    FIRSTNAME: "John",
    LASTNAME: "Doe",
    EMAIL: "test@example.com",
    ACCESS: null,
    REFRESH: null,
    CROCID: null,
    baseUrl: "http://localhost:3000"
  }
});

...