Add melange/apko build pipeline and Kubernetes manifests

- Add melange.yaml for distroless package build
- Add apko.yaml for minimal container image
- Add GitHub Actions workflow for melange/apko CI build
- Add Kubernetes manifests (deployment, service, configmap, secret, redis)
- Update Dockerfile, .gitignore, and docker-compose.yml

k8s/deployment.yaml

@@ -0,0 +1,71 @@
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: apcupsd-client
+  namespace: apcupsd
+  labels:
+    app.kubernetes.io/name: apcupsd-client
+    app.kubernetes.io/part-of: apcupsd-client
+spec:
+  replicas: 1
+  strategy:
+    type: RollingUpdate
+    rollingUpdate:
+      maxUnavailable: 0
+      maxSurge: 1
+  selector:
+    matchLabels:
+      app.kubernetes.io/name: apcupsd-client
+  template:
+    metadata:
+      labels:
+        app.kubernetes.io/name: apcupsd-client
+    spec:
+      securityContext:
+        runAsUser: 10001
+        runAsGroup: 10001
+        runAsNonRoot: true
+        fsGroup: 10001
+      containers:
+        - name: web
+          image: ghcr.io/k2patel/apcupsd-client:latest
+          ports:
+            - containerPort: 8000
+              protocol: TCP
+          envFrom:
+            - configMapRef:
+                name: apcupsd-client-config
+            - secretRef:
+                name: apcupsd-client-secret
+          livenessProbe:
+            httpGet:
+              path: /healthz
+              port: 8000
+            initialDelaySeconds: 15
+            periodSeconds: 30
+            timeoutSeconds: 5
+            failureThreshold: 3
+          readinessProbe:
+            httpGet:
+              path: /readyz
+              port: 8000
+            initialDelaySeconds: 5
+            periodSeconds: 10
+            timeoutSeconds: 5
+            failureThreshold: 3
+          resources:
+            requests:
+              memory: "128Mi"
+              cpu: "100m"
+            limits:
+              memory: "256Mi"
+              cpu: "500m"
+          securityContext:
+            readOnlyRootFilesystem: true
+            allowPrivilegeEscalation: false
+          volumeMounts:
+            - name: tmp
+              mountPath: /tmp
+      volumes:
+        - name: tmp
+          emptyDir: {}