Passing promscrape.cluster.memberNum argument in k8s is not easy as it is of type INT

[venkatbvc]

Is your feature request related to a problem? Please describe.

To use cluster feature of vmagent, promscrape.cluster.memberNum argument has to be passed. In k8s, It is difficult to pass this argument unless a wrapper script is written to start the vmagent. But in distroless, we cannot have a wrapper script.

Describe the solution you'd like

In k8s, cluster version can be deployed as statefulset, ${HOSTNAME##*-} gives the oridnal number of the pod. If memberNum parameter can be evaluated from the above expression then it will ease installation in k8s environment. Or read this from a file so that proper number would be generated.

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.

Additional context
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[hagen1778]

cc @tenmozes @f41gh7
is this related to operator/helm-charts repos?

[f41gh7]

I think, it's related to vmagent itself. If it improve user experience, we should it.

Example of usage for statefulset based deployments:

apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: vmagent
spec:
  template:
    spec:
      containers:
      - name: vmagent
        args:
         # must be enabled
        - envflag.enable
        env:
        - name: promscrape_cluster_memberNum
          valueFrom:
            fieldRef:
              fieldPath: metadata.name

[venkatbvc]

@f41gh7 Yes it is related to VMagent.

[valyala]

vmagent accepts statefulset pod names at -promscrape.cluster.memberNum command-line flag starting from v1.76.1. For example, the following command-line flag -promscrape.cluster.memberNum=vmagent-0 is equivalent to -promscrape.cluster.memberNum=0. See these docs for more details.