Create a cluster with five n1-standard-1 nodes

gcloud container clusters create --num-nodes --scopes "https://www.googleapis.com/auth/projecthosting,storage-rw"

The explain command in kubectl can tell us about the Deployment object.

kubectl explan deployment

We can also see all of the fields using the --recursive option.

kubectl explain deployment --recursive

You can use the explain command as you go through the lab to help you understand the structure of a Deployment object and understand what the individual fields do.

kubectl explain deployment.metadata.name

create your deployment object using kubectl create

kubectl create -f

Verify

kubectl get replicasets

View Pods

kubectl get pods

create service file for above config file

kubectl create -f services/auth.yaml

create and expose fontend deployment

kubectl create secret generic tls-certs --from-file tls/
kubectl create configmap nginx-frontend-conf --from-file=nginx/frontend.conf

kubectl create -f deployments/frontend.yaml
kubectl create -f services/frontend.yaml

Interact with frontend by external IP adn curling to it

curl -ks https://

You can also use the output templating feature of kubectl to use curl as a one-liner:

curl -ks https://`kubectl get svc frontend -o=jsonpath="{.status.loadBalancer.ingress[0].ip}"`

Now that we have a Deployment created, we can scale it. Do this by updating the spec.replicas field. You can look at an explanation of this field using the kubectl explain command again.

kubectl explain deployment.spec.replicas

The replicas field can be most easily updated using the kubectl scale command

kubectl scale deployment hello --replicas=5

Verify that there are now 5 hello Pods running:

kubectl get pods | grep hello- | wc -l

Now scale back the application:

kubectl scale deployment hello --replicas=3

To update your Deployment, run the following command

kubectl edit deployment hello

Change the image in the containers section of the Deployment to the following See the new ReplicaSet that Kubernetes creates.

kubectl get replicaset

You can also see a new entry in the rollout history

kubectl rollout history deployment/hello

If you detect problems with a running rollout, pause it to stop the update.

kubectl rollout pause deployment/hello

Verify the current state of the rollout

kubectl rollout status deployment/hello

You can also verify this on the Pods directly:

kubectl get pods -o jsonpath --template='{range .items[*]}{.metadata.name}{"\t"}{"\t"}{.spec.containers[0].image}{"\n"}{end}'

The rollout is paused which means that some pods are at the new version and some pods are at the older version. We can continue the rollout using the resume command.

kubectl rollout resume deployment/hello

Assume that a bug was detected in your new version. Since the new version is presumed to have problems, any users connected to the new Pods will experience those issues.

You will want to roll back to the previous version so you can investigate and then release a version that is fixed properly.

Use the rollout command to roll back to the previous version:

kubectl rollout undo deployment/hello

Verify the roll back in the history:

kubectl rollout history deployment/hello

Finally, verify that all the Pods have rolled back to their previous versions:

kubectl get pods -o jsonpath --template='{range .items[*]}{.metadata.name}{"\t"}{"\t"}{.spec.containers[0].image}{"\n"}{end}'

When you want to test a new deployment in production with a subset of your users, use a canary deployment. Canary deployments allow you to release a change to a small subset of your users to mitigate risk associated with new releases.

Create a canary deployment

create a new canary deployment for the new version:

kubectl create -f deployments/hello-canary.yaml

Verify the canary deployment

You can verify the hello version being served by the request:

curl -ks https://`kubectl get svc frontend -o=jsonpath="{.status.loadBalancer.ingress[0].ip}"`/version

Canary deployments in production - session affinity In this lab, each request sent to the Nginx service had a chance to be served by the canary deployment. But what if you wanted to ensure that a user didn't get served by the Canary deployment? A use case could be that the UI for an application changed, and you don't want to confuse the user. In a case like this, you want the user to "stick" to one deployment or the other.
You can do this by creating a service with session affinity. This way the same user will always be served from the same version. In the example below the service is the same as before, but a new sessionAffinity field has been added, and set to ClientIP. All clients with the same IP address will have their requests sent to the same version of the hello application

kind: Service
apiVersion: v1
metadata:
name: "hello"
spec:
sessionAffinity: ClientIP
selector:
app: "hello"
ports:
- protocol: "TCP"
port: 80
targetPort: 80

Due to it being difficult to set up an environment to test this, you don't need to here, but you may want to use sessionAffinity for canary deployments in production.

The Service

Use the existing hello service, but update it so that it has a selector app:hello, version: 1.0.0. The selector will match the existing "blue" deployment. But it will not match the "green" deployment because it will use a different version.
Update the service

kubectl apply -f services/hello-blue.yaml

Updating using Blue-Green Deployment
In order to support a blue-green deployment style, we will create a new "green" deployment for our new version. The green deployment updates the version label and the image path.

apiVersion: apps/v1 kind: Deployment
metadata:
name: hello-green
spec:
replicas: 3
selector:
matchLabels:
app: hello
template:
metadata:
labels:
app: hello
track: stable
version: 2.0.0
spec:
containers:
- name: hello
image: kelseyhightower/hello:2.0.0
ports:
- name: http
containerPort: 80
- name: health
containerPort: 81
resources:
limits:
cpu: 0.2
memory: 10Mi
livenessProbe:
httpGet:
path: /healthz
port: 81
scheme: HTTP
initialDelaySeconds: 5
periodSeconds: 15
timeoutSeconds: 5
readinessProbe:
httpGet:
path: /readiness
port: 81
scheme: HTTP
initialDelaySeconds: 5
timeoutSeconds: 1

Create the green deployment:

kubectl create -f deployments/hello-green.yaml

Once you have a green deployment and it has started up properly, verify that the current version of 1.0.0 is still being used:

curl -ks https://`kubectl get svc frontend -o=jsonpath="{.status.loadBalancer.ingress[0].ip}"`/version

Update the service to point to the new version:

kubectl apply -f services/hello-green.yaml

With the service is updated, the "green" deployment will be used immediately. You can now verify that the new version is always being used.

curl -ks https://`kubectl get svc frontend -o=jsonpath="{.status.loadBalancer.ingress[0].ip}"`/version