K6: Authorization in the Test Life Cycle

Grafana k6 OSS Support
1

I have been reading through the K6 documentation and am struggling to find a way to conform a K6 script to meet my needs. The scenario I imagine in my head:

// 1. init code
export function setup() {
  // 2. setup code
  // The VU would get setup here with authentication once
}
export default function (data) {
  // 3. VU code
  // The VU would run this code a repeated amount of times
}
export function teardown(data) {
  // 4. teardown code
  // The VU would be deauthed here after the VU code has ran its course

Unfortunately, from what I’ve read here: Test lifecycle, my understanding is that the above scenario isn’t possible. " setup is called at the beginning of the test, after the init stage but before the VU stage (default function), and teardown is called at the end of a test, after the VU stage ( default function). Therefore, VU number is 0 while executing the setup and teardown functions." I interpret this to mean that in the above scenario, all the VU’s would use the same authentication to run the VU code instead of each VU getting it’s own separate authentication.

If I simply exclude the setup and teardown sections, then each VU would get new authentication on each loop:

export default function (data) {
  // 3. VU code
  // VU gets authenticated
  // VU does a bunch of stuff
  // VU clears authentication
}

Is there a way to design K6 scripts with my intention (VU Authenticates once → VU code loop → Deauth at the end once)?

EDIT: I did not thoroughly research this topic enough. More information on this topic can be found here:

2

Please don’t just post a link to your question in another place, but the whole question :slight_smile:

3

My apologies. I’ve updated the post.

4

I am copy-pasting my response from stackoverflow below:

Yes, setup and teardown are global per the test run.

There is an issue about per VU setup/teardown, but it has not be prioritized highly as there is … other stuff which seem more important :).

I would also like to point out that the setup, teardown and the default code are run in separate JS VMs where the only shared memory (and it is copied between them) is the data that is returned by setup and is the first argument to default and teardown.

Currently, there are two workarounds (with varying success):

  1. If you are fine with not deauthenticating (which is fine for deauthenticating in a lot of cases) you can just authenticate on the first iteration using code like like if (__ITER == 0) { authenticate(); }
  2. Use the fact that setup can return an array of objects and authenticate all the VUs in the setup code and then each VU can get their authentication (I guess it is a token of some kind) from the array using the __VU variable which start at 1 for VUs that execute the default function. Later on teardown will get that same array and can deauthenticate everything. You might need to increase some ]timeouts](Options reference) and/or use http.batch.

Depending on how exactly you are going to authenticate and deauthenticate … there might be an even better option :).