Add Kubernetes deployment support (#38)

Provide Kubernetes Deployment for anyone who need to use it.

Author: pichuang

Diff for: k8s/README.md

@@ -0,0 +1,20 @@
+# Kubernetes Deployment
+
+```bash
+# Deploy the service
+$ kubectl apply -f chatgpt-lite-deployment.yaml -f env-secret.yaml
+namespace/chatgpt-lite created
+deployment.apps/chatgpt-lite created
+service/chatgpt-lite created
+secret/env created
+
+# Get the service
+$ kubectl -n chatgpt-lite get svc
+NAME           TYPE        CLUSTER-IP    EXTERNAL-IP   PORT(S)    AGE
+chatgpt-lite   ClusterIP   10.0.199.26   <none>        3000/TCP   7m8s
+
+# Use port-forward to access the service
+$ kubectl -n chatgpt-lite port-forward svc/chatgpt-lite 5566:3000
+Forwarding from 127.0.0.1:5566 -> 3000
+Forwarding from [::1]:5566 -> 3000
+```

Diff for: k8s/chatgpt-lite-deployment.yaml

@@ -0,0 +1,73 @@
+---
+apiVersion: v1
+kind: Namespace
+metadata:
+  name: chatgpt-lite
+---
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  labels:
+    app: chatgpt-lite
+  name: chatgpt-lite
+  namespace: chatgpt-lite
+spec:
+  replicas: 1
+  selector:
+    matchLabels:
+      app: chatgpt-lite
+  strategy: {}
+  template:
+    metadata:
+      labels:
+        app: chatgpt-lite
+    spec:
+      containers:
+        - env:
+            - name: AZURE_OPENAI_API_BASE_URL
+              valueFrom:
+                secretKeyRef:
+                  key: AZURE_OPENAI_API_BASE_URL
+                  name: env
+            - name: AZURE_OPENAI_API_KEY
+              valueFrom:
+                secretKeyRef:
+                  key: AZURE_OPENAI_API_KEY
+                  name: env
+            - name: AZURE_OPENAI_DEPLOYMENT
+              valueFrom:
+                secretKeyRef:
+                  key: AZURE_OPENAI_DEPLOYMENT
+                  name: env
+            - name: OPENAI_API_BASE_URL
+              valueFrom:
+                secretKeyRef:
+                  key: OPENAI_API_BASE_URL
+                  name: env
+            - name: OPENAI_API_KEY
+              valueFrom:
+                secretKeyRef:
+                  key: OPENAI_API_KEY
+                  name: env
+          image: docker.io/blrchen/chatgpt-lite:main
+          name: chatgpt-lite
+          ports:
+            - containerPort: 3000
+          resources: {}
+      restartPolicy: Always
+---
+apiVersion: v1
+kind: Service
+metadata:
+  creationTimestamp: null
+  labels:
+    app: chatgpt-lite
+  name: chatgpt-lite
+  namespace: chatgpt-lite
+spec:
+  ports:
+    - name: "3000"
+      port: 3000
+      targetPort: 3000
+  selector:
+    app: chatgpt-lite

Diff for: k8s/env-secret.yaml

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+---
+apiVersion: v1
+kind: Secret
+metadata:
+  name: env
+  namespace: chatgpt-lite
+type: Opaque
+data:
+  # echo -n 'Hello chatgpi-lite' | base64
+  # SGVsbG8gY2hhdGdwaS1saXRl
+  OPENAI_API_BASE_URL: ""
+  OPENAI_API_KEY: ""
+  AZURE_OPENAI_API_BASE_URL: ""
+  AZURE_OPENAI_API_KEY: ""
+  AZURE_OPENAI_DEPLOYMENT: ""