Fix #4: Adds files needed for deployment on Kubernetes

Dockerfile-deploy

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+# This file will produce the telescope's image needed for deployment (ex. on Kubernetes)
+#
+# CLI command to create an image using this file:
+# Assumption: `telescope-deploy` would be the image name. If you change this name, change the image name also on `telescope.yaml`
+# $ docker build -f Dockerfile-deploy -t telescope-deploy .            ----> notice the dot at the end!
+# to put the image on Docker Hub:
+# $ docker login                                                       ----> you need an account; use your credential
+# $ docker tag telescope-deploy <DockerId>/telescope-deploy:<version>  ----> ex. $ docker tag telescope-deploy username/telescope-deploy
+#          needs Docker Hub ID. We may ignore version (we are using latest in `telescope.yaml` which is the default version)
+#          otherwise make them consistent in image tag and in YAML file.
+# $ docker push <DockerId>/telescope-deploy:<version>                  ----> ignore version if you ignored in image tag
+
+
+# Dockerfile-deploy
+
+# First stage of building image
+###############################
+
+# Use `node` long term stable image as the parent to build this image
+FROM node:lts as builder
+
+# Change working directory on the image
+WORKDIR "/telescope"
+
+# Copy package.json and .npmrc from local to the image
+# Copy before bundle app source to make sure package-lock.json never gets involved
+COPY package.json ./
+COPY .npmrc ./
+
+# Install all Node.js modules on the image
+RUN npm install --no-package-lock --production
+
+
+# Second stage, making the final image
+# only keep run-requirment from last stage
+##########################################
+
+# Use `node` long term stable and slim version image as the parent to build final image
+# The slim version has minimal packages needed to run application
+# It doesn't have version control, compiler, and etc which makes it significantly smaller and more secure
+FROM node:lts-slim
+
+# Change working directory on the image
+WORKDIR "/telescope"
+
+# Copy dependencies from last stage
+COPY --from=builder /telescope/node_modules /telescope/node_modules
+
+# Bundle app source
+COPY . .
+
+# Set the environment to production
+ENV NODE_ENV production
+
+# Change the run time user to not be root any more
+# The node image has a run time user already set up
+USER node
+
+# Expose (manage) the server port on Kuberbetes
+
+# run the image with this command
+CMD ["npm", "start"]

telescope.yaml

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+# This file creates replicas number of Pods, all served with one Kubernetes Service resource
+# each pod has 2 containers (telescope and redis) as has been specified in following Deployment resource
+
+# Change <DockerID> with the Docker Hub namespace (ID/username) in this file
+# To deploy project on Kubernetes we must have telescope image from `Dockerfile-deploy` file pushed on Docker Hub (instruction in `Dockerfile-deploy`).
+# We need `kubectl` installed, and for local simulation of the deployment, `minikube` installed and running.
+# deploy the app using following command
+# $ kubectl create -f telescope.yaml
+# to watch the pods as they gets created
+# $ kubectl get pods --watch
+# to see stdout of containers (telescope or redis) in one specific instance (pod)
+# $ kubctl logs <pod name as shown by above command> -c [telescope | redis]   ---> ex. $ kubectl logs telescope-7b567445fc-pn7cb -c telescope
+# finally access to the app which is running in Kubernetes cluster using this command
+# $ minikube service telescope
+# we can scale the app using the following command (example: from 3 replicas to 5)
+# $ kubectl scale --replicas=5 telescope
+# re-creating and replacing resources defined in a YAML file (ONLY IN MINIKUBE):
+# $ kubectl replace --force -f telescope.yaml   -----> Will cause service outage; Do not use in real deployment in Kubernetes
+
+# Service resource
+## telescope needs a service resource to be accessible to the outside the cluster
+## Service resource also guarantees the same IP address after each restart
+
+# version of Kubernetes API- using stable version
+apiVersion: v1
+# resource type and label
+kind: Service
+metadata:
+  name: telescope
+# specifications of resource
+spec:
+  selector:
+    name: telescope
+  ports:
+    # the port that cluster is listening (exposed)
+    - port: 3000
+      # the port in each pod that Service maps traffic on
+      targetPort: 3000
+      # the exposed port will be manipulated as nodePort. If we don't define it, it would be a random number greater than/equal 30000
+      # this is the port number we will see when we access to service by cluster's IP address
+      nodePort: 30000
+  # This resource needs to communicate with outside of the cluster
+  # and share traffic between instances of app
+  type: LoadBalancer
+---
+# Deployment resource
+
+# version of Kubernetes API- stable version for deployment resource
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: telescope
+  labels:
+    # related to the service
+    app: telescope
+spec:
+  # at least 3 instances (pods) for resilient deployment, proper traffic management, and smooth updating the app
+  replicas: 3
+  selector:
+    matchLabels:
+      app: telescope
+  # label and specification of Pod
+  template:
+    metadata:
+      labels:
+        app: telescope
+    spec:
+      # shared file system between containers (redis and telescope)
+      volumes:
+        - name: storage
+          emptyDir: {}
+      # containers in this Pod (we have two)
+      containers:
+        # first container
+        - name: telescope
+          # change DockerID to telescope's Docker Hub username
+          image: <DockerID>/telescope-deploy:latest
+          # Always pull, because we are using the latest image version
+          imagePullPolicy: Always
+          ports:
+            - containerPort: 3000
+          livenessProbe:
+            httpGet:
+              # this path is implemented in our app. we can also check with home page ('/') to get 200 response
+              path: /health
+              port: 3000
+            initialDelaySeconds: 30
+            timeoutSeconds: 5
+          readinessProbe:
+            httpGet:
+              path: /health
+              port: 3000
+            initialDelaySeconds: 5
+            timeoutSeconds: 1
+
+        # second container
+        - name: redis
+          image: redis:latest
+          # Always pull, because we are using the latest image version
+          imagePullPolicy: Always
+          ports:
+            - containerPort: 6379
+          # mount storage to the shared file system
+          volumeMounts:
+            - name: storage
+              mountPath: /from-redis
+          # container health checks to apply restart policy on Pod
+          livenessProbe:
+            exec:
+              command:
+                - redis-cli
+                - ping
+            initialDelaySeconds: 30
+            timeoutSeconds: 5
+          readinessProbe:
+            exec:
+              command:
+                - redis-cli
+                - ping
+            initialDelaySeconds: 5
+            timeoutSeconds: 1