Experimental-prometheus-rw output to a multi-tenant Mimir deployment

Hi all,

I am trying to setup K6 output to a multi-tenant Mimir deployment via “experimental-prometheus-rw”

I have deployed multi-tenancy enabled Mimir OpenSource in K8s and grafana-agents running on different clusters can send metrics using X-Scope-OrgID header to different tenants successfully.

I cannot manage to set it up for K6 Prometheus Remote Write with “-o experimental-prometheus-rw” option. I have set following variables:


and I see the following error at the end of K6 run:

ERRO[0001] Failed to send the time series data to the endpoint error=“got status code: 401 instead expected a 2xx successful status code” output=“Prometheus remote write”

If I unset “K6_PROMETHEUS_RW_HEADERS_X-Scope-OrgID” environment variable, I see the metrics stored as “anonymous” tenant (default tenant on Mimir if no X-Scope-OrgID defined)

Anyone used Prometheus Remote Write with a multi-tenant Mimir deployment to a specific tenant?

Thanks in advance.
Suleyman Kutlu

Hi @snk,
welcome to the community forum :tada:

It seems you’re getting an unexpected error because at the moment the scope id header is not supported as you can check from this issue. Better API for HTTP Headers · Issue #101 · grafana/xk6-output-prometheus-remote · GitHub
Please, add a thumbs up reaction to the issue so we can raise the priority.

Are you sure you’re setting it? You should get an error from k6 similar to this:

level=error msg="invalid environment variable name 'K6_PROMETHEUS_RW_HEADERS_X-Scope-OrgId'"
1 Like

Hi @codebien

Thanks for the link. There is a slight difference though with the issue:

Documentation says env variable should be K6_PROMETHEUS_RW_HEADERS_=

So I have an env variable as stated in my question:


But the issue has


So which one should I use? I can try that as well :wink:

Thanks in advance…

Only if I use


I got that error about status code 401 at the end.

Other combinations I have tested below did not give any error but did not do anything neither


I never get that invalid environment variable error.