Load testing an API which uses oauth token for authorization using loadimpact k6

Question

I'm trying to load test an API (GET method) using loadimpact k6 which requires oauth token for authorization to get the successful response. I already have a postman collection file which does this by running pre-request script. The pre-request script will request token from the authorization server and then populates the token in the environment variable. I used the "Postman to LoadImpact converter" to generate the k6 script but it isn't doing any help. The script fails to get the access token.

The generated script from the converter is given below:

// Auto-generated by the Load Impact converter

import "./libs/shim/core.js";

export let options = { maxRedirects: 4 };

const Request = Symbol.for("request");
postman[Symbol.for("initial")]({
  options,
  collection: {
    currentAccessToken: "",
    "Client-Id": "",
    "Client-Secret": "",
    "Token-Scope": "",
    "Grant-Type": "client_credentials",
    "Access-Token-URL": "",
    accessTokenExpiry: ""
  }
});

export default function() {
  postman[Request]({
    name: "Collection Mock",
    id: "",
    method: "GET",
    address:
      "",
    headers: {
      Authorization: "Bearer {{currentAccessToken}}"
    },
    pre() {
      const echoPostRequest = {
        url: pm.environment.get("Access-Token-URL"),
        method: "POST",
        header: "Content-Type:x-www-form-urlencoded",
        body: {
          mode: "urlencoded",
          urlencoded: [
            { key: "client_id", value: pm.environment.get("Client-Id") },
            {
              key: "client_secret",
              value: pm.environment.get("Client-Secret")
            },
            { key: "grant_type", value: pm.environment.get("Grant-Type") },
            { key: "scope", value: pm.environment.get("Token-Scope") }
          ]
        }
      };

      var getToken = true;

      if (
        !pm.environment.get("accessTokenExpiry") ||
        !pm.environment.get("currentAccessToken")
      ) {
        console.log("Token or expiry date are missing");
      } else if (
        pm.environment.get("accessTokenExpiry") <= new Date().getTime()
      ) {
        console.log("Token is expired");
      } else {
        getToken = false;
        console.log("Token and expiry date are all good");
      }

      if (getToken === true) {
        pm.sendRequest(echoPostRequest, function(err, res) {
          console.log(err ? err : res.json());
          if (err === null) {
            console.log("Saving the token and expiry date");
            var responseJson = res.json();
            pm.environment.set("currentAccessToken", responseJson.access_token);

            var expiryDate = new Date();
            expiryDate.setSeconds(
              expiryDate.getSeconds() + responseJson.expires_in
            );
            pm.environment.set("accessTokenExpiry", expiryDate.getTime());
          }
        });
      }
    }
  });
}

The issue is with pm.sendRequest which is not supported by the converter and I'm not sure what the alternative is. So, I'm looking for ways to dynamically request access token from the authorization server and use that token to make a request to the API for load testing in k6 script.

Answer 1

I ended up using below code snippet to make a successful call for my purpose:

// Auto-generated by the Load Impact converter

import "./libs/shim/core.js";
import http from "k6/http";
import { check, sleep } from "k6";

export let options = {
  max_vus: 10,
  vus: 10,
  stages: [
    { duration: "1m", target: 10 }
  ]
}

const Request = Symbol.for("request");

pm.environment.set("currentAccessToken", "");
pm.environment.set("accessTokenExpiry", "");
pm.environment.set("clientId", "");
pm.environment.set("clientSecret", "");
pm.environment.set("tokenScope", "");
pm.environment.set("grantType", "");
pm.environment.set("accesstokenUrl", "");

pm.environment.set("apiUrl", "");

pm.environment.set("subscriptionKeys", "");

export default function() {     
    var getToken = true;

    if (!pm.environment.get("accessTokenExpiry") || !pm.environment.get("currentAccessToken")) {
        //console.log("Token or expiry date are missing");
    } else if (pm.environment.get("accessTokenExpiry") <= new Date().getTime()) {
        //console.log("Token is expired");
    } else {
        getToken = false;
        //console.log("Token and expiry date are all good");
    }

    if (getToken === true) {
        //get the access token first
        let res = http.post(pm.environment.get("accesstokenUrl"), {
        "client_id": pm.environment.get("clientId"),
        "client_secret": pm.environment.get("clientSecret"),
        "grant_type": pm.environment.get("grantType"),
        "scope": pm.environment.get("tokenScope")
        });

        var checkRes = check(res, {
            "Token Request status is 200": (r) => r.status === 200,
        });

        if (checkRes) {
            var responseJson = res.json();
            pm.environment.set("currentAccessToken", responseJson.access_token);
            var expiryDate = new Date();
            expiryDate.setSeconds(
              expiryDate.getSeconds() + responseJson.expires_in
            );
            pm.environment.set("accessTokenExpiry", expiryDate.getTime());
        }

        sleep(1);

        //make the api request using the access token and subscription keys (if required)
        let apiRes = http.get(pm.environment.get("apiUrl"),
        { 
            headers: { "Authorization": "Bearer " + pm.environment.get("currentAccessToken"), 
                       "Subscription-Key" : pm.environment.get("subscriptionKeys") 
            } 
        });
        check(apiRes, {
            "API Request status is 200": (res) => res.status === 200
        });

        sleep(3);
    }
}