3-kubernetize

Step 3: Deploy to Kubernetes

In this step, you will deploy the api service to Kubernetes.

Goals

• api is deployed to Kubernetes.
• api has been tested on Kubernetes.

Tasks

Start Kubernetes

For this tutorial you will be running Kubernetes locally on your machine using kind. kind stands for "Kubernetes in Docker" and is an easy way to run Kubernetes locally.

If you haven't already started kind, run the start script:`

./k8s/start-kind.sh

 ✓ Ensuring node image (kindest/node:v1.19.1) 🖼
 ✓ Preparing nodes 📦
 ✓ Writing configuration 📜
 ✓ Starting control-plane 🕹️
 ✓ Installing CNI 🔌
 ✓ Installing StorageClass 💾
Set kubectl context to "kind-kind"
You can now use your cluster with:

kubectl cluster-info --context kind-kind

Have a nice day! 👋

NOTE: If you get an error like:

ERROR: failed to create cluster: docker run error: command "docker run --hostname kind-control-plane
 --name kind-control-plane --label io.x-k8s.kind.role=control-plane --privileged --security-opt seccomp=unconfined
 --security-opt apparmor=unconfined --tmpfs /tmp --tmpfs /run --volume /var --volume /lib/modules:/lib/modules:ro --detach
 --tty --label io.x-k8s.kind.cluster=kind --net kind --restart=on-failure:1 --publish=0.0.0.0:80:80/TCP --publish=0.0.0.0:443:443/TCP
 --publish=127.0.0.1:61433:6443/TCP kindest/node:v1.19.1@sha256:98cf5288864662e37115e362b23e4369c8c4a408f99cbc06e58ac30ddc721600"
 failed with error: exit status 125

First, stop the web and api services you're running locally. Then start kind using the command above, then restart the web and api services using their start scripts.

Verify Kind

Verify that kind is working by running:

kubectl get node
NAME                 STATUS   ROLES    AGE   VERSION
kind-control-plane   Ready    master   33m   v1.19.1

Pod

A pod is a single replica of the application. Its specification looks like:

apiVersion: v1
kind: Pod
metadata:
  name: api
spec:
  containers:
    - name: api
      image: docker.io/lkysow/api:v0.1.0
      ports:
        - containerPort: 80

Create a file pod.yaml with the above contents. Change the image to whatever image name you tagged yours as.

Then apply the yaml file to your Kubernetes cluster with kubectl:

kubectl apply -f pod.yaml
pod/api created

You can see if it's working by running:

kubectl get pod
NAME   READY   STATUS    RESTARTS   AGE
api    1/1     Running   0          25s

You can get its logs by running:

kubectl logs api
2020-10-20T22:41:59.587Z [INFO]  Starting service: name=api-k8s upstreamURIs= upstreamWorkers=1 listenAddress=0.0.0.0:80 service type=http
2020-10-20T22:41:59.587Z [INFO]  Adding handler for UI static files
2020-10-20T22:41:59.587Z [INFO]  Settings CORS options: allow_creds=false allow_headers=Accept,Accept-Language,Content-Language,Origin,Content-Type allow_origins=*

A pod isn't enough though. If it gets deleted, or the node it's running on crashes, it will never be restarted:

kubectl delete pod api
pod "api" deleted

kubectl get pod
No resources found in default namespace.

Deployment

What you need is a deployment. A deployment starts pods but also manages them to ensure the right number is running.

Create a deployment.yaml file:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: api
  labels:
    app: api
spec:
  replicas: 1
  selector:
    matchLabels:
      app: api
  template:
    metadata:
      labels:
        app: api
    spec:
      containers:
        - name: api
          image: docker.io/lkysow/api:v0.1.0
          ports:
            - containerPort: 80

Change the image to your image name and then apply the deployment:

kubectl apply -f deployment.yaml
deployment.apps/api create

Ensure it's been applied:

kubectl get deployment
NAME   READY   UP-TO-DATE   AVAILABLE   AGE
api    1/1     1            1           24s

You can see the pod it's created:

kubectl get pod
NAME                  READY   STATUS    RESTARTS   AGE
api-56dbdd4fc-jbr22   1/1     Running   0          61s

If you delete the pod, you'll see another one get created:

kubectl delete pod api-56dbdd4fc-jbr22
pod "api-56dbdd4fc-jbr22" deleted

kubectl get pod
NAME                  READY   STATUS    RESTARTS   AGE
api-56dbdd4fc-7n6md   1/1     Running   0          6s

Verify

Verify that the deployment is working as expected by using the kubectl port-forward command:

kubectl port-forward api-56dbdd4fc-7n6md 8888:80
Forwarding from 127.0.0.1:8888 -> 80
Forwarding from [::1]:8888 -> 80

If you navigate to http://localhost:8888/ you should see:

{
  "name": "api-k8s",
  "uri": "/",
  "type": "HTTP",
  "ip_addresses": [
    "10.244.0.7"
  ],
  "start_time": "2020-10-20T22:53:17.988606",
  "end_time": "2020-10-20T22:53:17.990155",
  "duration": "1.548424ms",
  "body": "Hello World",
  "code": 200
}

Conclusion

api is now running on Kubernetes!

Next Step

Go to 4-networking.