kube-prometheus-stack issue scraping metrics

General Cluster Information:

• Kubernetes version: 1.19.13
• Cloud being used: private
• Installation method: kubeadm init
• Host OS: Ubuntu 20.04.1 LTS
• CNI and version: Weave Net: 2.7.0
• CRI and version: Docker: 19.3.13

I am trying to get kube-prometheus-stack helm chart to work. This seems for most targets to work, however, some targets stay down as shown in the screenshot below.

Are there any suggestions, how I can get kube-etcd, kube-controller-manager and kube-scheduler monitored by Prometheus?

I deployed the helm chart as mentioned here and applied the suggestion here to get the kube-proxy monitored by Prometheus.

Thanks in advance for any help!

EDIT 1:

- job_name: monitoring/my-stack-kube-prometheus-s-kube-controller-manager/0
  honor_timestamps: true
  scrape_interval: 30s
  scrape_timeout: 10s
  metrics_path: /metrics
  scheme: http
  bearer_token_file: /var/run/secrets/kubernetes.io/serviceaccount/token
  relabel_configs:
  - source_labels: [__meta_kubernetes_service_label_app]
    separator: ;
    regex: kube-prometheus-stack-kube-controller-manager
    replacement: $1
    action: keep
  - source_labels: [__meta_kubernetes_service_label_release]
    separator: ;
    regex: my-stack
    replacement: $1
    action: keep
  - source_labels: [__meta_kubernetes_endpoint_port_name]
    separator: ;
    regex: http-metrics
    replacement: $1
    action: keep
  - source_labels: [__meta_kubernetes_endpoint_address_target_kind, __meta_kubernetes_endpoint_address_target_name]
    separator: ;
    regex: Node;(.*)
    target_label: node
    replacement: ${1}
    action: replace
  - source_labels: [__meta_kubernetes_endpoint_address_target_kind, __meta_kubernetes_endpoint_address_target_name]
    separator: ;
    regex: Pod;(.*)
    target_label: pod
    replacement: ${1}
    action: replace
  - source_labels: [__meta_kubernetes_namespace]
    separator: ;
    regex: (.*)
    target_label: namespace
    replacement: $1
    action: replace
  - source_labels: [__meta_kubernetes_service_name]
    separator: ;
    regex: (.*)
    target_label: service
    replacement: $1
    action: replace
  - source_labels: [__meta_kubernetes_pod_name]
    separator: ;
    regex: (.*)
    target_label: pod
    replacement: $1
    action: replace
  - source_labels: [__meta_kubernetes_pod_container_name]
    separator: ;
    regex: (.*)
    target_label: container
    replacement: $1
    action: replace
  - source_labels: [__meta_kubernetes_service_name]
    separator: ;
    regex: (.*)
    target_label: job
    replacement: ${1}
    action: replace
  - source_labels: [__meta_kubernetes_service_label_jobLabel]
    separator: ;
    regex: (.+)
    target_label: job
    replacement: ${1}
    action: replace
  - separator: ;
    regex: (.*)
    target_label: endpoint
    replacement: http-metrics
    action: replace
  - source_labels: [__address__]
    separator: ;
    regex: (.*)
    modulus: 1
    target_label: __tmp_hash
    replacement: $1
    action: hashmod
  - source_labels: [__tmp_hash]
    separator: ;
    regex: "0"
    replacement: $1
    action: keep
  kubernetes_sd_configs:
  - role: endpoints
    namespaces:
      names:
      - kube-system
- job_name: monitoring/my-stack-kube-prometheus-s-kube-etcd/0
  honor_timestamps: true
  scrape_interval: 30s
  scrape_timeout: 10s
  metrics_path: /metrics
  scheme: http
  bearer_token_file: /var/run/secrets/kubernetes.io/serviceaccount/token
  relabel_configs:
  - source_labels: [__meta_kubernetes_service_label_app]
    separator: ;
    regex: kube-prometheus-stack-kube-etcd
    replacement: $1
    action: keep
  - source_labels: [__meta_kubernetes_service_label_release]
    separator: ;
    regex: my-stack
    replacement: $1
    action: keep
  - source_labels: [__meta_kubernetes_endpoint_port_name]
    separator: ;
    regex: http-metrics
    replacement: $1
    action: keep
  - source_labels: [__meta_kubernetes_endpoint_address_target_kind, __meta_kubernetes_endpoint_address_target_name]
    separator: ;
    regex: Node;(.*)
    target_label: node
    replacement: ${1}
    action: replace
  - source_labels: [__meta_kubernetes_endpoint_address_target_kind, __meta_kubernetes_endpoint_address_target_name]
    separator: ;
    regex: Pod;(.*)
    target_label: pod
    replacement: ${1}
    action: replace
  - source_labels: [__meta_kubernetes_namespace]
    separator: ;
    regex: (.*)
    target_label: namespace
    replacement: $1
    action: replace
  - source_labels: [__meta_kubernetes_service_name]
    separator: ;
    regex: (.*)
    target_label: service
    replacement: $1
    action: replace
  - source_labels: [__meta_kubernetes_pod_name]
    separator: ;
    regex: (.*)
    target_label: pod
    replacement: $1
    action: replace
  - source_labels: [__meta_kubernetes_pod_container_name]
    separator: ;
    regex: (.*)
    target_label: container
    replacement: $1
    action: replace
  - source_labels: [__meta_kubernetes_service_name]
    separator: ;
    regex: (.*)
    target_label: job
    replacement: ${1}
    action: replace
  - source_labels: [__meta_kubernetes_service_label_jobLabel]
    separator: ;
    regex: (.+)
    target_label: job
    replacement: ${1}
    action: replace
  - separator: ;
    regex: (.*)
    target_label: endpoint
    replacement: http-metrics
    action: replace
  - source_labels: [__address__]
    separator: ;
    regex: (.*)
    modulus: 1
    target_label: __tmp_hash
    replacement: $1
    action: hashmod
  - source_labels: [__tmp_hash]
    separator: ;
    regex: "0"
    replacement: $1
    action: keep
  kubernetes_sd_configs:
  - role: endpoints
    namespaces:
      names:
      - kube-system
- job_name: monitoring/my-stack-kube-prometheus-s-kube-scheduler/0
  honor_timestamps: true
  scrape_interval: 30s
  scrape_timeout: 10s
  metrics_path: /metrics
  scheme: http
  bearer_token_file: /var/run/secrets/kubernetes.io/serviceaccount/token
  relabel_configs:
  - source_labels: [__meta_kubernetes_service_label_app]
    separator: ;
    regex: kube-prometheus-stack-kube-scheduler
    replacement: $1
    action: keep
  - source_labels: [__meta_kubernetes_service_label_release]
    separator: ;
    regex: my-stack
    replacement: $1
    action: keep
  - source_labels: [__meta_kubernetes_endpoint_port_name]
    separator: ;
    regex: http-metrics
    replacement: $1
    action: keep
  - source_labels: [__meta_kubernetes_endpoint_address_target_kind, __meta_kubernetes_endpoint_address_target_name]
    separator: ;
    regex: Node;(.*)
    target_label: node
    replacement: ${1}
    action: replace
  - source_labels: [__meta_kubernetes_endpoint_address_target_kind, __meta_kubernetes_endpoint_address_target_name]
    separator: ;
    regex: Pod;(.*)
    target_label: pod
    replacement: ${1}
    action: replace
  - source_labels: [__meta_kubernetes_namespace]
    separator: ;
    regex: (.*)
    target_label: namespace
    replacement: $1
    action: replace
  - source_labels: [__meta_kubernetes_service_name]
    separator: ;
    regex: (.*)
    target_label: service
    replacement: $1
    action: replace
  - source_labels: [__meta_kubernetes_pod_name]
    separator: ;
    regex: (.*)
    target_label: pod
    replacement: $1
    action: replace
  - source_labels: [__meta_kubernetes_pod_container_name]
    separator: ;
    regex: (.*)
    target_label: container
    replacement: $1
    action: replace
  - source_labels: [__meta_kubernetes_service_name]
    separator: ;
    regex: (.*)
    target_label: job
    replacement: ${1}
    action: replace
  - source_labels: [__meta_kubernetes_service_label_jobLabel]
    separator: ;
    regex: (.+)
    target_label: job
    replacement: ${1}
    action: replace
  - separator: ;
    regex: (.*)
    target_label: endpoint
    replacement: http-metrics
    action: replace
  - source_labels: [__address__]
    separator: ;
    regex: (.*)
    modulus: 1
    target_label: __tmp_hash
    replacement: $1
    action: hashmod
  - source_labels: [__tmp_hash]
    separator: ;
    regex: "0"
    replacement: $1
    action: keep
  kubernetes_sd_configs:
  - role: endpoints
    namespaces:
      names:
      - kube-system

This is because Prometheus is monitoring wrong endpoints of those targets and/or targets don't expose metrics endpoint.

Take controller-manager for example:

1. Change bind-address (default: 127.0.0.1):

$ sudo vi /etc/kubernetes/manifests/kube-controller-manager.yaml
apiVersion: v1
kind: Pod
metadata:
  ...
spec:
  containers:
  - command:
    - kube-controller-manager
    ...
    - --bind-address=<your control-plane IP or 0.0.0.0>
    ...

If you are using control-plane IP, you need to change livenessProbe and startupProbe host, too.

2. Change endpoint(service) port (default: 10252):

$ kubectl edit service prometheus-kube-prometheus-kube-controller-manager -n kube-system
apiVersion: v1
kind: Service
...
spec:
  clusterIP: None
  ports:
  - name: http-metrics
    port: 10257
    protocol: TCP
    targetPort: 10257
 ...

3. Change servicemonitor scheme (default: http):

$ kubectl edit servicemonitor prometheus-kube-prometheus-kube-controller-manager -n prometheus
apiVersion: monitoring.coreos.com/v1
kind: ServiceMonitor
...
spec:
  endpoints:
  - bearerTokenFile: /var/run/secrets/kubernetes.io/serviceaccount/token
    port: http-metrics
    scheme: https
    tlsConfig:
      caFile: /var/run/secrets/kubernetes.io/serviceaccount/ca.crt
      insecureSkipVerify: true
  jobLabel: jobLabel
  ...