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4. Managing Deployments Using Kubernetes Engine

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Overview

  • Goal

    • Practice in scaling and managing containers so you can accomplish these sommon scenarios where multiple heterogeous deployments are being used.

  • Deployment scenarios

    • Continuous Deployment

    • Blue-Green Deployments

    • Canary Deployments

  • What you’ll do

    • Practice with kybectl tool

    • Create deployment yaml files

    • Lanch, update, and scale deployments

    • Practice with updating deployments and deployment styles

Introduction to deployments

  • What is Heterogeneous deployment

    • Typically involve connecting two or more distinct infrastructure environments or regions to address a specific technical or operarion need.

    • Heterogeneout Deployments are called “hybrid”, “multi-cloud”, or “public-private”, depending upon the specifics of the deployment.

    • Hetetogeneous deployments include those tht span regions within a single cloud environment, multiple public cloud envieonments (multi-cloud), or a combination of on-preises and public cloud environments (hybrid or public-private).

  • Single environment or region’s business and technical challenges

    • Maxed out resources: In any single environment, particularly in on-premises environments, you might not have the compute, networking, and storage resources to meet your production needs.

    • Limited geographic reach: Deployments in a single environment require people who are geographically distant from one another to access one deployment. Their traffic might travel around the world to a central location.

    • Limited availability: Web-scale traffic patterns challenge applications to remain fault-tolerant and resilient.

    • Vendor lock-in: Vendor-level platform and infrastructure abstractions can prevent you from porting applications.

    • Inflexible resources: Your resources might be limited to a particular set of compute, storage, or networking offerings

H.P can help address these challenges, but they must be architected using programmatic and deterministic processes and procedures. One-off or ad-hoc deployment procedures can cause deployments or processes to be brittle and intolerant of failures

  • Three common scenarios for heterogeneous deployment

    • multi-cloud deployments

    • fronting on-premises data

    • continuous

Ref

Setup

✔️ Set zone

gcloud config set compute/zone us-central1-a

✔️ Get sample code

gsutil -m cp -r gs://spls/gsp053/orchestrate-with-kubernetes .
cd orchestrate-with-kubernetes/kubernetes
gcloud container clusters create bootcamp --num-nodes 5 --scopes
"https://www.googleapis.com/auth/projecthosting,storage-rw"

Learn about the deployment object

✔️ Take a look at the Deployment object.

kubectl explain deployment

See all of the fields using the —recursive option

kubectl explain deployment --recursive

Go through the lab to help you understand the structure of a Deployment object and understatnd what the individual fields do.

kubectl explain deployment.metadata.name

Create a deployment

✔️ Update the deployments/auth.yaml configuration file

vi deployments/auth.yaml

Change the image in the containers section of the Deployment to the following

...
containers:
- name: auth
  image: "kelseyhightower/auth:1.0.0"
...

✔️ Create a simple deployment

cat deployments/auth.yaml

(Output)

apiVersion: apps/v1
kind: Deployment
metadata:
  name: auth
spec:
  replicas: 1
  selector:
    matchLabels:
      app: auth
  template:
    metadata:
      labels:
        app: auth
        track: stable
    spec:
      containers:
        - name: auth
          image: "kelseyhightower/auth:1.0.0"
          ports:
            - name: http
              containerPort: 80
            - name: health
              containerPort: 81
...

When you run the kubectl create command to create the auth deployment, it will make one pod that conforms to the data in the Deployment manifest. This means we can scale the number of Pods by changing the number specified in the replicas field.

Create deployment

kubectl create -f deployments/auth.yaml

Verify that deployment was created

kubectl get deployments

Verify that a ReplicaSet was created for Deployment

kubectl get replicasets

✔️ View the Pods that were created as part of our Deployment.

The single Pod is created by the Kubernetes when the ReplicaSet is created

kubectl get pods

✔️ Create service for our auth deployment.

kubectl create -f services/auth.yaml

✔️ Create and expose the deployment

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

  • What is Configmap ?

    • API object used to store non-confidential data in key-value pairs.

  • What is Secrets ?

    • Object that contains a small amount of sensitive data such as a password, a token, or a key.

✔️ Interact with the frontend by grabbing its external IP and then curling to it

kubectl get services frontend
curl -ks https://<EXTERNAL-IP>

Use the output templating feature

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

✔️ Scale a Deployment

kubectl scale deployment hello --replicas=5

Verify that there are now 5 hello Pods running

kubectl get pods | grep hello- | wc -l

Scale back the application

kubectl scale deployment hello --replicas=3

Verify that you have the corrext number of Pods

kubectl get pods | grep hello- | wc -l

Rolling update

Deployments support updating images to a new version through a
rolling update mechanism. When a Deployment is updated with a new version,
it creates a new ReplicaSet and slowly increases the number of replicas
in the new ReplicaSet as it decreases the replicas in the old ReplicaSet.

✔️ Trigger a rolling update

Update Deployment

kubectl edit deployment hello

Change the image in the containers section of the Deployment to the following

...
containers:
  image: kelseyhightower/hello:2.0.0
...

See the new ReplicaSet

kubectl get replicaset

See a new entry in the rollout history

kubectl rollout history deployment/hello

✔️ Pause a rolling update

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

Verify this on the Pods dirextly

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

✔️ Resume a rolling update

kubectl rollout resume deployment/hello
kubectl rollout status deployment/hello

✔️ Rollback an update

Roll back to the previous version

kubectl rollout undo deployment/hello

Verify the rollback in the history

kubectl rollout history deployment/hello

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}'

Canary deployments

Canary deployments allow you to release a change to a small subset of your users to mitigate risk associated with new releases.

A canary deployment consists of a separate deployment with your new version and a service that targets both your normal, stable deployment as well as your canary deployment.

✔️ Create a canary deployment

cat deployments/hello-canary.yaml

(output)

apiVersion: apps/v1
kind: Deployment
metadata:
  name: hello-canary
spec:
  replicas: 1
  selector:
    matchLabels:
      app: hello
  template:
    metadata:
      labels:
        app: hello
        track: canary
        # Use ver 2.0.0 so it matches version on service selector
        version: 2.0.0
    spec:
      containers:
        - name: hello
          image: kelseyhightower/hello:2.0.0
          ports:
            - name: http
              containerPort: 80
            - name: health
              containerPort: 81
...
kubectl create -f deployments/hello-canary.yaml
kubectl get deployments

✔️ Verify the canary deployment

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

✔️ Canary deployments in production - session affinity

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

Blue-green deployments

Use your existing hello deployment for the "blue" version. The deployments will be accessed via a Service which will act as the router. Once the new "green" version is up and running, you'll switch over to using that version by updating the Service.

✔️ The service

Update the service

kubectl apply -f services/hello-blue.yaml

✔️ Updating using Blue-Green Deployment

Create a “green” deployment for new version

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

Verify thT the srrent 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

Verify that the new version is always being used

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

✔️ Blue-Green Rollback

You can rollback to the old version in the same way. While the ‘blue” deployment is still running, just update the service back to the old version.

kubectl apply -f services/hello-blue.yaml

Verify that the right version is now being used

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

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