Kubernetes: poner Pods en cuarentena

Raul Unzue Pulido 4 febrero, 2021 Kubernetes Deja un comentario 1,543 Vistas

Kubernetes: poner Pods en cuarentena

Hoy os voy a explicar cómo poner Pods en cuarentena en Kubernetes y para qué os podría ser interesante.

Imaginaros que tenéis un conjunto de contenedores desplegados con un ReplicaSet, y queréis investigar uno de ellos, pero sin que esto afecte al servicio que el resto de contenedores estén dando en Producción.

Para que ReplicaSet no tenga el poder sobre el contenedor que os interesa, lo colocaremos en cuarentena.

Así que os pongo un ejemplo para que lo veáis más claro, os dejo un ejemplo de ReplicaSet:

raulunzue@KBMASTER:~$ nano nginx-deployment-elblogdenegu.yml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment-elblogdenegu
  labels:
    app: nginx
spec:
  replicas: 6
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
        - name: nginx
          image: nginx:latest
          ports:
            - containerPort: 8080

raulunzue@KBMASTER:~$ nano nginx-deployment-elblogdenegu.yml

apiVersion: apps/v1

kind: Deployment

metadata:

name: nginx-deployment-elblogdenegu

labels:

app: nginx

spec:

replicas: 6

selector:

matchLabels:

app: nginx

template:

metadata:

labels:

app: nginx

spec:

containers:

- name: nginx

image: nginx:latest

ports:

- containerPort: 8080

Ejecutamos el fichero para crear los contenedores:

raulunzue@kbmaster:~/k8s$ kubectl apply -f nginx-deployment-elblogdenegu.yml 
deployment.apps/nginx-deployment-elblogdenegu created

1 2	raulunzue@kbmaster:~/k8s$ kubectl apply -f nginx-deployment-elblogdenegu.yml deployment.apps/nginx-deployment-elblogdenegu created

Revisamos que se generan los contenedores:

raulunzue@kbmaster:~/k8s$ kubectl get pods --show-labels
NAME                                             READY   STATUS    RESTARTS   AGE   LABELS
nginx-deployment-elblogdenegu-74b8cb59b8-5x99f   1/1     Running   0          54s   app=nginx,pod-template-hash=74b8cb59b8
nginx-deployment-elblogdenegu-74b8cb59b8-l8fhj   1/1     Running   0          54s   app=nginx,pod-template-hash=74b8cb59b8
nginx-deployment-elblogdenegu-74b8cb59b8-mm48k   1/1     Running   0          54s   app=nginx,pod-template-hash=74b8cb59b8
nginx-deployment-elblogdenegu-74b8cb59b8-nt8mz   1/1     Running   0          54s   app=nginx,pod-template-hash=74b8cb59b8
nginx-deployment-elblogdenegu-74b8cb59b8-trbbv   1/1     Running   0          54s   app=nginx,pod-template-hash=74b8cb59b8
nginx-deployment-elblogdenegu-74b8cb59b8-wrdf7   1/1     Running   0          54s   app=nginx,pod-template-hash=74b8cb59b8

raulunzue@kbmaster:~/k8s$ kubectl get pods --show-labels

NAME READY STATUS RESTARTS AGE LABELS

nginx-deployment-elblogdenegu-74b8cb59b8-5x99f 1/1 Running 0 54s app=nginx,pod-template-hash=74b8cb59b8

nginx-deployment-elblogdenegu-74b8cb59b8-l8fhj 1/1 Running 0 54s app=nginx,pod-template-hash=74b8cb59b8

nginx-deployment-elblogdenegu-74b8cb59b8-mm48k 1/1 Running 0 54s app=nginx,pod-template-hash=74b8cb59b8

nginx-deployment-elblogdenegu-74b8cb59b8-nt8mz 1/1 Running 0 54s app=nginx,pod-template-hash=74b8cb59b8

nginx-deployment-elblogdenegu-74b8cb59b8-trbbv 1/1 Running 0 54s app=nginx,pod-template-hash=74b8cb59b8

nginx-deployment-elblogdenegu-74b8cb59b8-wrdf7 1/1 Running 0 54s app=nginx,pod-template-hash=74b8cb59b8

Lo que haremos es separar uno de los contenedores, poniéndolo en cuarentena, cambiando la etiqueta de la siguiente forma:

Colocamos un app=debug
Y adicionalmente un “overwrite” ya que existe ya la etiqueta

raulunzue@kbmaster:~/k8s$ kubectl label pod nginx-deployment-elblogdenegu-74b8cb59b8-5x99f app=debug --overwrite
pod/nginx-deployment-elblogdenegu-74b8cb59b8-5x99f labeled

1 2	raulunzue@kbmaster:~/k8s$ kubectl label pod nginx-deployment-elblogdenegu-74b8cb59b8-5x99f app=debug --overwrite pod/nginx-deployment-elblogdenegu-74b8cb59b8-5x99f labeled

Una vez hecho esto y comprobado:

raulunzue@kbmaster:~/k8s$ kubectl get pods --show-labels
NAME                                             READY   STATUS    RESTARTS   AGE   LABELS
nginx-deployment-elblogdenegu-74b8cb59b8-5x99f   1/1     Running   0          59s   app=debug,pod-template-hash=74b8cb59b8
nginx-deployment-elblogdenegu-74b8cb59b8-l8fhj   1/1     Running   0          59s   app=nginx,pod-template-hash=74b8cb59b8
nginx-deployment-elblogdenegu-74b8cb59b8-mm48k   1/1     Running   0          59s   app=nginx,pod-template-hash=74b8cb59b8
nginx-deployment-elblogdenegu-74b8cb59b8-nt8mz   1/1     Running   0          59s   app=nginx,pod-template-hash=74b8cb59b8
nginx-deployment-elblogdenegu-74b8cb59b8-trbbv   1/1     Running   0          59s   app=nginx,pod-template-hash=74b8cb59b8
nginx-deployment-elblogdenegu-74b8cb59b8-wrdf7   1/1     Running   0          59s   app=nginx,pod-template-hash=74b8cb59b8

raulunzue@kbmaster:~/k8s$ kubectl get pods --show-labels

NAME READY STATUS RESTARTS AGE LABELS

nginx-deployment-elblogdenegu-74b8cb59b8-5x99f 1/1 Running 0 59s app=debug,pod-template-hash=74b8cb59b8

nginx-deployment-elblogdenegu-74b8cb59b8-l8fhj 1/1 Running 0 59s app=nginx,pod-template-hash=74b8cb59b8

nginx-deployment-elblogdenegu-74b8cb59b8-mm48k 1/1 Running 0 59s app=nginx,pod-template-hash=74b8cb59b8

nginx-deployment-elblogdenegu-74b8cb59b8-nt8mz 1/1 Running 0 59s app=nginx,pod-template-hash=74b8cb59b8

nginx-deployment-elblogdenegu-74b8cb59b8-trbbv 1/1 Running 0 59s app=nginx,pod-template-hash=74b8cb59b8

nginx-deployment-elblogdenegu-74b8cb59b8-wrdf7 1/1 Running 0 59s app=nginx,pod-template-hash=74b8cb59b8

Lo que pasa con ReplicaSet, es que generará el mismo número de contenedores nuevos que hayamos puesto en cuarentena. En este caso, sólo uno:

raulunzue@kbmaster:~/k8s$ kubectl get pods --show-labels
NAME                                             READY   STATUS    RESTARTS   AGE   LABELS
nginx-deployment-elblogdenegu-74b8cb59b8-5x99f   1/1     Running   0          2m   app=debug,pod-template-hash=74b8cb59b8
nginx-deployment-elblogdenegu-74b8cb59b8-l8fhj   1/1     Running   0          2m   app=nginx,pod-template-hash=74b8cb59b8
nginx-deployment-elblogdenegu-74b8cb59b8-mm48k   1/1     Running   0          2m   app=nginx,pod-template-hash=74b8cb59b8
nginx-deployment-elblogdenegu-74b8cb59b8-ms7gn   1/1     Running   0          34s   app=nginx,pod-template-hash=74b8cb59b8
nginx-deployment-elblogdenegu-74b8cb59b8-nt8mz   1/1     Running   0          2m   app=nginx,pod-template-hash=74b8cb59b8
nginx-deployment-elblogdenegu-74b8cb59b8-trbbv   1/1     Running   0          2m   app=nginx,pod-template-hash=74b8cb59b8
nginx-deployment-elblogdenegu-74b8cb59b8-wrdf7   1/1     Running   0          2m   app=nginx,pod-template-hash=74b8cb59b8