BulatGazizov-dev · BulatGazizov-dev · Mar 25, 2026
diff --git a/k8s/README.md b/k8s/README.md
@@ -0,0 +1,239 @@
+# Lab 09
+
+## Architecture Overview
+
+I have one deployment and one service.
+Deployment contains three pods (replicas).
+
+Service configured to route all requests to some random pod on my deployment.
+
+I also opened external port using "minikube service"
+
+**Resource Allocation Strategy:**
+
+3 Pods in total requres 300m cpu and 384Mi and limites to 600m and 768Mi
+
+## Manifest Files
+
+**File "deployment.yml":** Deployment Manifest
+Description: Defines how your Python app runs in Kubernetes—specifies the container image, resource constraints, health checks, and update strategy.
+
+- 100m CPU / 128Mi memory: Conservative estimates for a lightweight Python app. If your app uses more (e.g., data processing), increase requests to avoid throttling.
+- 10s liveness / 5s readiness: Liveness is slower because restarting a pod is expensive; readiness is faster because removing from load balancer is cheap.
+- maxSurge=1, maxUnavailable=0: Ensures zero downtime during updates—critical for user-facing services.
+
+**File "service.yml:** Service Manifest
+Description: Creates a stable network endpoint that routes traffic to your 3 pods. Acts as a load balancer.
+
+- NodePort: Perfect to test access.
+- targetPort 5000: Must match your app's listening port.
+- Selector: Automatically discovers pods.
+
+## Deployment Evidence
+
+```bash
+
+(.venv) bulatgazizov@fedora:~/Projects/DevOps-Core-Course$ minikube kubectl cluster-info
+Kubernetes control plane is running at https://192.168.49.2:8443
+CoreDNS is running at https://192.168.49.2:8443/api/v1/namespaces/kube-system/services/kube-dns:dns/proxy
+
+To further debug and diagnose cluster problems, use 'kubectl cluster-info dump'.
+(.venv) bulatgazizov@fedora:~/Projects/DevOps-Core-Course$ minikube kubectl get nodes
+NAME       STATUS   ROLES           AGE   VERSION
+minikube   Ready    control-plane   10m   v1.35.1
+```
+
+kubectl get all output
+kubectl get pods,svc with detailed view
+kubectl describe deployment <name> showing replicas and strategy
+Screenshot or curl output showing app working
+
+## Operations Performed
+
+### Commands used to deploy
+
+```bash
+kubectl apply -f k8s/deployment.yml
+deployment.apps/python-app created
+```
+
+```bash
+kubectl get deployments
+NAME         READY   UP-TO-DATE   AVAILABLE   AGE
+python-app   3/3     3            3           3m30s
+(.venv) bulatgazizov@fedora:~/Projects/DevOps-Core-Course$ kubectl get pods
+NAME                          READY   STATUS    RESTARTS   AGE
+python-app-868d6ff4d5-6jkwm   1/1     Running   0          5m45s
+python-app-868d6ff4d5-d9lzc   1/1     Running   0          5m45s
+python-app-868d6ff4d5-j7q95   1/1     Running   0          5m45s
+(.venv) bulatgazizov@fedora:~/Projects/DevOps-Core-Course$ kubectl describe deployment python-app
+Name:                   python-app
+Namespace:              default
+CreationTimestamp:      Wed, 25 Mar 2026 12:42:59 +0300
+Labels:                 app=python-app
+Annotations:            deployment.kubernetes.io/revision: 1
+Selector:               app=python-app
+Replicas:               3 desired | 3 updated | 3 total | 3 available | 0 unavailable
+StrategyType:           RollingUpdate
+MinReadySeconds:        0
+RollingUpdateStrategy:  25% max unavailable, 25% max surge
+Pod Template:
+  Labels:  app=python-app
+  Containers:
+   python-app:
+    Image:      bulatgazizov/python_app:latest
+    Port:       5000/TCP
+    Host Port:  0/TCP
+    Limits:
+      cpu:     200m
+      memory:  256Mi
+    Requests:
+      cpu:         100m
+      memory:      128Mi
+    Liveness:      http-get http://:5000/health delay=10s timeout=1s period=5s #success=1 #failure=3
+    Readiness:     http-get http://:5000/ delay=5s timeout=1s period=3s #success=1 #failure=3
+    Environment:   <none>
+    Mounts:        <none>
+  Volumes:         <none>
+  Node-Selectors:  <none>
+  Tolerations:     <none>
+Conditions:
+  Type           Status  Reason
+  ----           ------  ------
+  Available      True    MinimumReplicasAvailable
+  Progressing    True    NewReplicaSetAvailable
+OldReplicaSets:  <none>
+NewReplicaSet:   python-app-868d6ff4d5 (3/3 replicas created)
+Events:
+  Type    Reason             Age   From                   Message
+  ----    ------             ----  ----                   -------
+  Normal  ScalingReplicaSet  6m    deployment-controller  Scaled up replica set python-app-868d6ff4d5 from 0 to 3
+  ```
+
+### Service
+
+Service access method and verification
+
+```bash
+kubectl apply -f k8s/service.yml 
+service/python-app-service configured
+(.venv) bulatgazizov@fedora:~/Projects/DevOps-Core-Course$ kubectl get svc -o wide
+NAME                 TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)        AGE     SELECTOR
+kubernetes           ClusterIP   10.96.0.1        <none>        443/TCP        4h53m   <none>
+python-app-service   NodePort    10.105.222.193   <none>        80:30098/TCP   2m4s    app=python-app
+(.venv) bulatgazizov@fedora:~/Projects/DevOps-Core-Course$ minikube service python-app-service --url
+http://192.168.49.2:30098
+(.venv) bulatgazizov@fedora:~/Projects/DevOps-Core-Course$ kubectl describe service python-app-service
+Name:                     python-app-service
+Namespace:                default
+Labels:                   <none>
+Annotations:              <none>
+Selector:                 app=python-app
+Type:                     NodePort
+IP Family Policy:         SingleStack
+IP Families:              IPv4
+IP:                       10.105.222.193
+IPs:                      10.105.222.193
+Port:                     <unset>  80/TCP
+TargetPort:               5000/TCP
+NodePort:                 <unset>  30098/TCP
+Endpoints:                10.244.0.3:5000,10.244.0.5:5000,10.244.0.4:5000
+Session Affinity:         None
+External Traffic Policy:  Cluster
+Internal Traffic Policy:  Cluster
+Events:                   <none>
+(.venv) bulatgazizov@fedora:~/Projects/DevOps-Core-Course$ kubectl get endpoints
+Warning: v1 Endpoints is deprecated in v1.33+; use discovery.k8s.io/v1 EndpointSlice
+NAME                 ENDPOINTS                                         AGE
+kubernetes           192.168.49.2:8443                                 4h54m
+python-app-service   10.244.0.3:5000,10.244.0.4:5000,10.244.0.5:5000   3m
+```
+
+![alt text](images/image.png)
+
+### Scaling demonstration output
+
+```bash
+kubectl get pods -w
+NAME                          READY   STATUS              RESTARTS   AGE
+python-app-868d6ff4d5-6jkwm   1/1     Running             0          4h19m
+python-app-868d6ff4d5-d9lzc   1/1     Running             0          4h19m
+python-app-868d6ff4d5-dhcb4   0/1     ContainerCreating   0          4s
+python-app-868d6ff4d5-j7q95   1/1     Running             0          4h19m
+python-app-868d6ff4d5-vwqn4   0/1     ContainerCreating   0          4s
+python-app-868d6ff4d5-dhcb4   0/1     Running             0          8s
+python-app-868d6ff4d5-vwqn4   0/1     Running             0          12s
+python-app-868d6ff4d5-dhcb4   1/1     Running             0          15s
+python-app-868d6ff4d5-vwqn4   1/1     Running             0          19s
+
+kubectl rollout status deployment/python-app
+deployment "python-app" successfully rolled out
+```
+
+### Rolling update demonstration output
+
+I update image version and applied new configuration file:
+
+```bash
+
+kubectl apply -f k8s/deployment.yml 
+deployment.apps/python-app configured
+
+kubectl get pods -o wide
+NAME                          READY   STATUS              RESTARTS   AGE     IP           NODE       NOMINATED NODE   READINESS GATES
+python-app-6c4c988cd6-pbvh2   0/1     ContainerCreating   0          13s     <none>       minikube   <none>           <none>
+python-app-868d6ff4d5-6jkwm   1/1     Running             0          4h59m   10.244.0.5   minikube   <none>           <none>
+python-app-868d6ff4d5-d9lzc   1/1     Running             0          4h59m   10.244.0.3   minikube   <none>           <none>
+python-app-868d6ff4d5-j7q95   1/1     Running             0          4h59m   10.244.0.4   minikube   <none>           <none>
+(.venv) bulatgazizov@fedora:~/Projects/DevOps-Core-Course$ kubectl get pods -o wide
+NAME                          READY   STATUS    RESTARTS   AGE     IP           NODE       NOMINATED NODE   READINESS GATES
+python-app-6c4c988cd6-pbvh2   1/1     Running   0          28s     10.244.0.8   minikube   <none>           <none>
+python-app-6c4c988cd6-vc6qj   0/1     Running   0          6s      10.244.0.9   minikube   <none>           <none>
+python-app-868d6ff4d5-6jkwm   1/1     Running   0          4h59m   10.244.0.5   minikube   <none>           <none>
+python-app-868d6ff4d5-d9lzc   1/1     Running   0          4h59m   10.244.0.3   minikube   <none>           <none>
+
+kubectl get pods -o wide
+NAME                          READY   STATUS    RESTARTS   AGE    IP            NODE       NOMINATED NODE   READINESS GATES
+python-app-6c4c988cd6-pbvh2   1/1     Running   0          2m3s   10.244.0.8    minikube   <none>           <none>
+python-app-6c4c988cd6-qzshb   1/1     Running   0          90s    10.244.0.10   minikube   <none>           <none>
+python-app-6c4c988cd6-vc6qj   1/1     Running   0          101s   10.244.0.9    minikube   <none>           <none>
+```
+
+```
+kubectl rollout status deployment/python-app
+deployment "python-app" successfully rolled out
+(.venv) bulatgazizov@fedora:~/Projects/DevOps-Core-Course$ kubectl rollout history deployment/python-app
+deployment.apps/python-app 
+REVISION  CHANGE-CAUSE
+1         <none>
+2         <none>
+
+(.venv) bulatgazizov@fedora:~/Projects/DevOps-Core-Course$ kubectl rollout undo deployment/python-app
+deployment.apps/python-app rolled back
+(.venv) bulatgazizov@fedora:~/Projects/DevOps-Core-Course$ kubectl rollout history deployment/python-app
+deployment.apps/python-app 
+REVISION  CHANGE-CAUSE
+2         <none>
+3         <none>
+```
+
+## Production Considerations
+
+What health checks did you implement and why?
+
+- Liveness Probe (/health endpoint): Restarts the container if it becomes unresponsive. Checks every 5 seconds after a 10-second startup delay.
+- Readiness Probe (/ endpoint): Removes the pod from the load balancer if it can't serve traffic. Checks every 3 seconds after a 5-second delay.
+
+Resource limits rationale
+
+- We have a fairly simple application, I allocate 100m for cpu usage and limit 200m, I also allocate 128 MB of memory with a limit of 256 MB.
+- Limits protect cluster stability.
+
+How would you improve this for production?
+
+- If we talking deployment overall, for production I may add HorizontalPodAutoscaler to scale based on container metrics.
+- Also, for production environment it's better to switch from NodePort to ClusterIP + Ingress for production (more flexible routing, TLS termination)
+
+Monitoring and observability strategy
+
+- We may reuse grafana & prometheus from previous labs in kubernetes, also connect kubernetes metrics to prometheus.
diff --git a/k8s/deployment.yml b/k8s/deployment.yml
@@ -0,0 +1,46 @@
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: python-app
+  labels:
+    app: python-app
+spec:
+  replicas: 3
+  strategy:
+    type: RollingUpdate
+    rollingUpdate:
+      maxSurge: 1        # Extra pods during update
+      maxUnavailable: 0
+  selector:
+    matchLabels:
+      app: python-app
+  template:
+    metadata:
+      labels:
+        app: python-app
+    spec:
+      containers:
+      - name: python-app
+        image: bulatgazizov/python_app:1.0.1
+        ports: 
+        - containerPort: 5000
+        resources:
+          requests:
+            memory: "128Mi"
+            cpu: "100m"
+          limits:
+            memory: "256Mi"
+            cpu: "200m"
+        livenessProbe:
+          httpGet:
+            path: /health
+            port: 5000
+          initialDelaySeconds: 10
+          periodSeconds: 5
+
+        readinessProbe:
+          httpGet:
+            path: /
+            port: 5000
+          initialDelaySeconds: 5
+          periodSeconds: 3
diff --git a/k8s/images/image.png b/k8s/images/image.png
diff --git a/k8s/service.yml b/k8s/service.yml
@@ -0,0 +1,12 @@
+apiVersion: v1
+kind: Service
+metadata:
+  name: python-app-service
+spec:
+  type: NodePort
+  ports:
+  - port: 80
+    protocol: TCP
+    targetPort: 5000
+  selector:
+    app: python-app