Debug log in readable format

Grafana k6
1

Kindly let me know is there any option to get request and response in readable format with k6 for debugging purpose.

I’m using the below command to write into log :

k6 run --logformat=raw --http-debug=full .\Main.js 2> http_debug.txt

The problem I’m facing is the response I’m getting is in unreadable format:

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│ólÑ{:┼▀$4ûB¼8╨UH^Γ┌G¬Zτ╘J∙M▄ªmh]Ω▀Lp┌φ▒q╚X▒·VHûåZ»╨┌@ê┴¬╣"f╨⌠Q,2º0,L╘ΩvMÖ╨▐⌠¥/╛ÿ?V┼MU{P╙sR8╦▀L 

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How can I view something in readable way?

2

Any help here is appreciated. Thanks!!!

@mstoykov @imiric

3

Hi @divinp,

that looks like you’re logging a binary response, which will always look unreadable if you output it with --http-debug=full.

In these cases I would suggest logging the headers only (so just --http-debug), and selectively doing console.log(resp.body) on responses whose bodies you know are plain text (checking the Content-Type header, maybe).

4

@imiric : Most of my responses are not in text/html format, and mostly are in json and other formats, so how can I view the response of these requests.

5

If they’re in JSON then they should render OK with --http-debug=full.

If “other formats” includes binary data, then you’ll need to decode it appropriately depending on the format (Content-Type) and console.log() the plain text data. Again, --http-debug=full will not render these responses correctly as it doesn’t process the response bodies.

6

@imiric : The below snapshot is having content type as json but still its unreadable, I have given http-debug=full. Can u please help.

image
image933×553 43.3 KB

7

It looks like the content is brotli-encoded. Ideally, http-debug=full would decode the response but I suspect it is not (otherwise you would see the JSON in clear-text).

You may want to consider using a web proxy application like Fiddler, charlesproxy, mitmproxy, et. al, along with setting the https_proxy environment variable to the address that the proxy listens on. Doing so will route all requests through that proxy and allow you to view the HTTP request/response data in a more intuitive UI. They should also take care of any content encoding.

2 Likes
8

Thanks @Tom , do we have any documentation about setting http_proxy in k6?

9

For Linux, use:

$ export HTTPS_PROXY=https://localhost:<port>

For Windows and Powershell, use:

$Env:https_proxy="localhost:<port>"

When you then run the k6 command (in the same terminal), you should see the requests appear in the web proxy tool.

1 Like
11

Thanks @Tom , it worked like charm.

12

Glad to see the proxy approach worked for you.

We’ve had a few issues with --http-debug so far (#986, #1042), and this is an additional one that doesn’t work as users expect it to, so I created #2112.

In upcoming versions we’d like to introduce a better way of debugging responses, see #1043, but it’s among a long list of wanted features, so feel free to give it a thumbs up in support. :slight_smile:

1 Like