Write response body to file

Grafana k6 OSS Support
1

Is there a convenient way to write the response body to an html file for debugging purposes?

Many Thanks

OTG Load Testing

2

The easiest thing was to console log the response body and redirect stderr to a file:
k6 run test.js 2>resp.html

Do a little editing and open in a browser

3

To somewhat improve the UX of that, you can also use the --logformat raw or --logformat json and --console-output=./path/to/console-log-file.log

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4

Hi @ned does --console-output=./filename.log takes only the outputs from console.log() ?

I run the below command using the docker-compose setup.
docker-compose run k6 run --logformat raw tests.js --console-output=./test.csv

This shows me permission denied. Any thoughts ?

Note that --console-output with a windows version of k6 works perfectly fine.

5

Hope Ned doesn’t mind me jumping in :slight_smile:

Yes, and also console.error(), console.info(), etc.

As for the permission denied error, that has to do with Docker. A few months ago the image was changed to use an unprivileged user, so if you want to write inside the container or to a bind volume (the default docker-compose.yml mounts ./samples:/scripts), you’ll have to specify the --user/-u option, either by making it run as root with -u root (not recommended), or by using the host’s UID/GID like so:

docker-compose run -u "$(id -u):$(id -g)" k6 run --logformat raw --console-output=/scripts/test.csv /scripts/stages.js

I’ll make a note to mention this in our docs.

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