Accept Multi Values in One Header When Using byHttpHeader

[Kirchen99]

Description

This PR extends the feature in #104. With a "separator" in the config the header value can be split.

e.g.

"authorization":
  "resourceAttributes":
    "apiVersion": "metrics.k8s.io/v1beta1"
    "namespace": "{{ .Value }}"
    "resource": "pods"
  "rewrites":
    "byHttpHeader":
      "name": "X-Scope-OrgID"
      "separator": "|"

Motivation

We also put kube-rbac-proxy in front of Loki (https://grafana.com/docs/loki/latest/). And Loki 2.6 enabled multi-tenant queries: https://grafana.com/blog/2022/07/27/grafana-loki-2.6-release/

The required format from loki is like this:

curl -H 'X-Scope-OrgID:Tenant1|Tenant2|Tenant3' \
  -G -s "http://localhost:3100/loki/api/v1/query" \
  --data-urlencode \
  'query=sum(rate({job="varlogs"}[10m])) by (level)' | jq

[ibihim]

Hi,

this commit that is merged into kube-rbac-proxy enables to specify the same header several times and all of them should be taken into consideration:

9fd649a

Is this enough to satisfy your needs?

[Kirchen99]

Hi,

this commit that is merged into kube-rbac-proxy enables to specify the same header several times and all of them should be taken into consideration:

9fd649a

Is this enough to satisfy your needs?

Not really. We use kube-rbac-proxy for Grafana Loki. Grafana Loki accepts only one header value and separating their names by the | character.

Maybe I should have a look at Grafana Loki, if it is possible to make a PR to let it accept same header several times.

Here is the document from Grafana Loki:

Here is a standard LogQL query to Tenant1:

curl -H 'X-Scope-OrgID:Tenant1 -G -s  "http://localhost:3100/loki/api/v1/query" \
  --data-urlencode \
  'query=sum(rate({job="varlogs"}[10m])) by (level)' | jq

Getting to a multi-tenant query is simple! Just make a small change to the X-Scope-OrgID header, which identifies the tenants you want to query. Specify as many tenants as you need, separating their names by the | character.

In this example, this cross-tenant query is written to target Tenant1, Tenant2, and Tenant3 for the requested data:

curl -H 'X-Scope-OrgID:Tenant1|Tenant2|Tenant3' \
  -G -s "http://localhost:3100/loki/api/v1/query" \
  --data-urlencode \
  'query=sum(rate({job="varlogs"}[10m])) by (level)' | jq

[dbluxo]

Hi @ibihim, we would also find this feature super helpful, could you maybe look at this PR again?

[sathieu]

Suggested change

	Sep string `json:"separator,omitempty"`
	Separator string `json:"separator,omitempty"`

NB: I'm not a reviewer here, just adding a suggestion.