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Prerrequisites

  • Conectividad a la API de Kubernetes

El plugin debe poder llegar a API de forma remota para poder extraer la información.

  • Permisos

Para hacer las solicitudes a través de la api, la cuenta utilizada para autenticar en la ejecución requiere de unos determinados permisos.

Asignación de permisos

A continuación se describen los pasos a seguir para crear un usuario con los permisos suficientes para obtener los datos de la monitorización.

  1. Creación de un “​Cluster role​” de lectura. Se debe crear un fichero.yaml con el siguiente contenido :
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: node-reader
rules:
- apiGroups: [""]
  resources: ["nodes"]
  verbs: ["get", "list"]

---

apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: pod-reader
rules:
- apiGroups: [""]
  resources: ["pods"]
  verbs: ["get", "list"]

---

apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: deployment-reader
rules:
- apiGroups: ["apps"]
  resources: ["deployments"]
  verbs: ["get", "list"]

---

apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: metrics-reader
rules:
- apiGroups: ["metrics.k8s.io"]
  resources: ["*"]
  verbs: ["get", "list"]

---

apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: namespace-reader
rules:
- apiGroups: [""]
  resources: ["namespaces"]
  verbs: ["get", "list"]

---

apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: component-status-reader
rules:
- apiGroups: [""]
  resources: ["componentstatuses"]
  verbs: ["get", "list"]

---

apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: node-reader-binding
subjects:
- kind: ServiceAccount
  name: default
  namespace: default
roleRef:
  kind: ClusterRole
  name: node-reader
  apiGroup: rbac.authorization.k8s.io

---

apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: pod-reader-binding
subjects:
- kind: ServiceAccount
  name: default
  namespace: default
roleRef:
  kind: ClusterRole
  name: pod-reader
  apiGroup: rbac.authorization.k8s.io

---

apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: deployment-reader-binding
subjects:
- kind: ServiceAccount
  name: default
  namespace: default
roleRef:
  kind: ClusterRole
  name: deployment-reader
  apiGroup: rbac.authorization.k8s.io

---

apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: metrics-reader-binding
subjects:
- kind: ServiceAccount
  name: default
  namespace: default
roleRef:
  kind: ClusterRole
  name: metrics-reader
  apiGroup: rbac.authorization.k8s.io

---

apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: namespace-reader-binding
subjects:
- kind: ServiceAccount
  name: default
  namespace: default
roleRef:
  kind: ClusterRole
  name: namespace-reader
  apiGroup: rbac.authorization.k8s.io

---

apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: component-status-reader-binding
subjects:
- kind: ServiceAccount
  name: default
  namespace: default
roleRef:
  kind: ClusterRole
  name: component-status-reader
  apiGroup: rbac.authorization.k8s.io
  
---

apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: node-reader
rules:
- apiGroups: [""]
  resources: ["nodes"]
  verbs: ["get", "list"]
- nonResourceURLs: ["/healthz", "/healthz/ping", "/healthz/log", "/healthz/etcd", "/healthz/poststarthook/crd-informer-synced", "/healthz/poststarthook/generic-apiserver-start-informers", "/healthz/poststarthook/start-apiextensions-controllers", "/healthz/poststarthook/start-apiextensions-informers"]
  verbs: ["get"]
  
---
    
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: service-reader
rules:
- apiGroups: [""]
  resources: ["services"]
  verbs: ["get", "list", "watch"]
- nonResourceURLs: ["/api/v1/services"]
  verbs: ["get"]
  
---
  
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: service-reader-binding
subjects:
- kind: ServiceAccount
  name: default
  namespace: default  
roleRef:
  kind: ClusterRole
  name: service-reader
  apiGroup: rbac.authorization.k8s.io

2. Después se debe aplicar el cluster role :

kubectl apply -f fichero.yaml
  • Instalar metrics server

Para instalar el addon de “​metrics-server​”, será necesario descargarlo en el entorno de Kubernetes. Se puede obtener de su proyecto de github:

https://github.com/kubernetes-incubator/metrics-server

Una vez descargado solo se tiene que desplegar mediante el comando “​kubectl​”:

kubectl apply -f https://github.com/kubernetes-sigs/metrics-server/releases/latest/download/components.yaml

Se puede verificar que el despliegue se haya realizado con éxito si al lanzar el siguiente comando el estado de su API figura como “​true​”:

kubectl get apiservices | grep metrics-server
v1beta1.metrics.k8s.io    kube-system/metrics-server True 1m

Si el despliegue tiene éxito, el API de “​metrics-server​” debería quedar accesible:

​kubectl get --raw "/apis/metrics.k8s.io/v1beta1/"
{"kind":"APIResourceList","apiVersion":"v1","groupVersion":"metrics.k8s.io/v1beta1","res
ources":[{"name":"nodes","singularName":"","namespaced":false,"kind":"NodeMetrics
","verbs":["get","list"]},{"name":"pods","singularName":"","namespaced":true,"kind":"P
odMetrics","verbs":["get","list"]}]}

Además, pasados algunos segundos, se deberían poder obtener datos de uso de CPU y memoria de contenedores y nodos:

$ ​kubectl top node
NAMECPU(cores) CPU%MEMORY(bytes)MEMORY%
kube93m968Mi56%4%
$ ​kubectl top pod
NAMECPU(cores)MEMORY(bytes)
pod10m3Mi
pod20m3Mi
pod30m2Mi
pod40m3Mi
pod50m1Mi

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