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Launch Graph Manager

Recap Core Concepts

PODS, ReplicaSets, Deployments, Namespaces

PODs

apiVersion: v1
kind: Pod
metadata:
  name: nginx-pod
spec:
  containers:
  - name: nginx
    image: nginx:1.7.9

And then...

$ kubectl apply -f <(cat <<EOF
apiVersion: v1
kind: Pod
metadata:
  name: nginx-pod
spec:
  containers:
  - name: nginx
    image: nginx:1.7.9
EOF)

Note: there's a shorthand for this:

$ kubectl run nginx --image=nginx --generator=run-pod/v1

ReplicaSets

$ kubectl get replicaset
NAME DESIRED CURRENT READY AGE

new-replica-set 4 4 0 5m17s

Deleting a pod

$ kubectl delete pod new-replica-set-2jn6r

Exercise 1

- apiVersion: v1
+ apiVersion: apps/v1
kind: ReplicaSet
metadata:
  name: replicaset-1
spec:
  replicas: 2
  selector:
    matchLabels:
      tier: frontend
  template:
    metadata:
      labels:
        tier: frontend
    spec:
      containers:
      - name: nginx
        image: nginx

Exercise 2

apiVersion: apps/v1
kind: ReplicaSet
metadata:
  name: replicaset-1
spec:
  replicas: 2
  selector:
    matchLabels:
      tier: frontend
  template:
    metadata:
      labels:
-        tier: frontend
+        tier: nginx
    spec:
      containers:
      - name: nginx
        image: nginx
$ kubectl delete replicaset replicaset-{1,2}

Editing an existing replicaset online:

$ kubectl edit replicaset new-replica-set

or better yet:

$ kubectl get rs new-replica-set > /tmp/replicaset.yml

which should get the replicaset with the problematic image.

Replication Controller vs Replica Sets

Replication Controller

apiVersion: v1
kind: ReplicationController
metadata:
  name: myapp-rc
  labels:
    app: myapp
    type: front-end
spec:
  template:
    metadata:
      labels:
        name: myapp-pod
        type: front-end
    spec:
      containers:
      - name: nginx-container
        image: nginx
  replicas: 3

Replica Set

apiVersion: apps/v1
kind: ReplicaSet
metadata:
  name: myapp-replicaset
  labels:
    app: myapp
    type: front-end
spec:
  template:
    metadata:
      name: myapp-pod
      labels:
        name: myapp
        type: front-end
    spec:
      containers:
      - name: nginx-container
        image: nginx
  replicas: 3
  selector:
    matchLabels:
      type: front-end

Deployments

apiVersion: apps/v1
kind: Deployment
metadata:
  name: myapp-replicaset
  labels:
    app: myapp
    type: front-end
spec:
  template:
    metadata:
      name: myapp-pod
      labels:
        name: myapp
        type: front-end
    spec:
      containers:
      - name: nginx-container
        image: nginx
  replicas: 3
  selector:
    matchLabels:
      type: front-end

See everything at once:

$ kubectl get all

Cheatsheets

https://kubernetes.io/docs/reference/kubectl/cheatsheet/ https://github.com/dennyzhang/cheatsheet-kubernetes-A4

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