Thanos-Query/Query-Frontend does not show any metrics

Basically, I had installed Prometheues-Grafana from the kube-prometheus-stack using the provided helm chart repo prometheus-community

# helm repo add prometheus-community https://prometheus-community.github.io/helm-charts
# helm install kube-prometheus-stack prometheus-community/kube-prometheus-stack

They are working fine.

But the problem I am facing now is integrating Thanos with this existing kube-prometheus-stack.

I installed thanos from the bitnami helm chart repo

# helm repo add bitnami https://charts.bitnami.com/bitnami
# helm install thanos bitnami/thanos

I can load the Thanos Query Frontend GUI, but no metrics showing there.

I am struggling now to get it worked properly. Is it because of Thanos from a completely different helm chart and Prometheus-operator-grafana stack from another helm chart ?.

My Kubernetes cluster on AWS has been created using Kops. And, I use Gitlab pipeline and helm to deploy apps to the cluster.

It's not enough to simply install them, you need to integrate prometheus with thanos.

Below I'll describe all steps you need to perform to get the result.

First short theory. The most common approach to integrate them is to use thanos sidecar container for prometheus pod. You can read more here.

How this is done:

(considering that installation is clean, it can be easily deleted and reinstalled from the scratch).

1. Get thanos sidecar added to the prometheus pod.

Pull kube-prometheus-stack chart:

$ helm pull prometheus-community/kube-prometheus-stack --untar

You will have a folder with a chart. You need to modify values.yaml, two parts to be precise:

# Enable thanosService
prometheus:
  thanosService:
    enabled: true # by default it's set to false

# Add spec for thanos sidecar
prometheus:
  prometheusSpec:
    thanos:
      image: "quay.io/thanos/thanos:v0.24.0"
      version: "v0.24.0"

Keep in mind, this feature is still experimental:

## This section is experimental, it may change significantly without deprecation notice in any release.
## This is experimental and may change significantly without backward compatibility in any release.
## ref: https://github.com/prometheus-operator/prometheus-operator/blob/main/Documentation/api.md#thanosspec

Once it's done, install the prometheus chart with edited values.yaml:

$ helm install prometheus . -n prometheus --create-namespace # installed in prometheus namespace

And check that sidecar is deployed as well:

$ kubectl get pods -n prometheus | grep prometheus-0
prometheus-prometheus-kube-prometheus-prometheus-0       3/3     Running   0          67s

It should be 3 containers running (by default it's 2). You can inspect it in more details with kubectl describe command.

2. Setup thanos chart and deploy it.

Pull the thanos chart:

$ helm pull bitnami/thanos --untar

Edit values.yaml:

query:
  dnsDiscovery:
    enabled: true
    sidecarsService: "prometheus-kube-prometheus-thanos-discovery" # service which was created before
    sidecarsNamespace: "prometheus" # namespace where prometheus is deployed

Save and install this chart with edited values.yaml:

$ helm install thanos . -n thanos --create-namespace

Check that it works:

$ kubectl logs thanos-query-xxxxxxxxx-yyyyy -n thanos

We are interested in this line:

level=info ts=2022-02-24T15:32:41.418475238Z caller=endpointset.go:349 component=endpointset msg="adding new sidecar with [storeAPI rulesAPI exemplarsAPI targetsAPI MetricMetadataAPI]" address=10.44.1.213:10901 extLset="{prometheus=\"prometheus/prometheus-kube-prometheus-prometheus\", prometheus_replica=\"prometheus-prometheus-kube-prometheus-prometheus-0\"}"

3. Now go to the UI and see that metrics are available:

Good article to read:

• Deep Dive into Thanos-Part II