feat: add bonus debugging scenarios and tips for mock exams

Author: sysops-26

mock-exams/MOCK-EXAM-01-SOLUTIONS.md

@@ -5,9 +5,40 @@
 
 ---
 
+## Pro Tips & Time Savers
+
+### Multiple Solution Approaches
+- **Fast path (Imperative)**: Use `kubectl run`, `kubectl create` for quick creation
+- **Flexible path (Declarative)**: Use YAML files for complex configs, can reuse across environments
+- **Cost**: Declarative takes 2-3 minutes longer but reduces errors on complex Deployments
+
+### Debugging Checklist
+When tasks fail, use this sequence:
+1. `kubectl get <resource> -n <namespace>` — Status check
+2. `kubectl describe pod <name> -n <ns>` — See Events section for root cause
+3. `kubectl logs pod <name> -n <ns>` — Check container logs
+4. `kubectl logs pod <name> -n <ns> --previous` — Check crashed container logs
+5. `kubectl get <resource> -o yaml` — Inspect full spec for typos
+
+### Common Exam Mistakes (Avoid These!)
+- ❌ Forgetting `-n <namespace>` in commands (defaults to `default`)
+- ❌ Typos in label selectors (e.g., `app=web` vs `app: web` in YAML)
+- ❌ Not setting `restartPolicy: Never` for Jobs/CronJobs
+- ❌ Missing `selector` field in Deployment YAML (required in v1, not v1beta1)
+- ❌ Using `docker build` instead of `podman build` (exam uses Podman)
+- ❌ Pod `serviceAccountName` is immutable — must delete & recreate if wrong
+
+### Time Management Tips
+- Flag difficult questions (5+ min) and return later
+- Use `kubectl explain <resource>` to verify schema (faster than docs)
+- Copy working YAML blocks and modify rather than typing from scratch
+- Save common templates as local files for paste-and-edit
+
+---
+
 ## Question 1 — Pod with Resources and Labels [3%]
 
-**Solution:**
+### ✅ Fast Approach (Imperative — 30 seconds)
 
 ```bash
 kubectl run web-pod --image=nginx:1.25 \
@@ -17,13 +48,18 @@ kubectl run web-pod --image=nginx:1.25 \
   -n default
 ```
 
-Or via YAML:
+**Why choose this**: Fastest if you already know all parameters. No YAML editing needed.
+
+### ✅ Flexible Approach (Declarative — 1.5 minutes)
+
+Create `web-pod.yaml`:
 
 ```yaml
 apiVersion: v1
 kind: Pod
 metadata:
   name: web-pod
+  namespace: default
   labels:
     app: web
 spec:
@@ -39,10 +75,15 @@ spec:
         memory: 256Mi
 ```
 
-**Verification:**
+Then apply: `kubectl apply -f web-pod.yaml`
+
+**Why choose this**: If unsure about parameters, YAML is self-documenting. Can also export and reuse.
+
+### 🔍 Verification
+
 ```bash
 kubectl get pod web-pod -o yaml | grep -A 5 "resources\|labels"
-# Should show:
+# Expected output:
 # labels:
 #   app: web
 # resources:
@@ -54,6 +95,27 @@ kubectl get pod web-pod -o yaml | grep -A 5 "resources\|labels"
 #     memory: 128Mi
 ```
 
+Or more detailed:
+```bash
+kubectl describe pod web-pod
+# Look for "Limits" and "Requests" sections
+```
+
+### ⚠️ Common Pitfalls & How to Avoid
+
+| Mistake | What Happens | Fix |
+|---------|--------------|-----|
+| Forget `-n default` | Goes to `default` namespace (usually OK) but get habit | Always explicit: `-n default` |
+| Typo in labels `app=web vs app: web` | In YAML only `:` works; CLI uses `=` | CLI: `key=value`, YAML: `key: value` |
+| Set limits lower than requests | Pod creation fails | Always: requests ≤ limits |
+| Image doesn't exist | Pod stuck in `ImagePullBackOff` | Verify image exists in registry first |
+
+### 📝 Exam Notes
+
+- **Score criteria**: Full marks if Pod created with all specs, any approach (imperative/declarative)
+- **Partial credit**: Missing label → -1 point, Resource mismatch → -1 point
+- **Typical time**: 2-3 minutes (including verification)
+
 ---
 
 ## Question 2 — Multi-Container Pod [4%]
@@ -703,6 +765,105 @@ kubectl get pvc -n advanced
 
 ---
 
+## Bonus: Question 16B — Debugging Pod Image Pull Error [Debugging Skill]
+
+### Problem Diagnosis
+
+When you see `ImagePullBackOff`, the Pod spec has an invalid or inaccessible image. Check events:
+
+```bash
+kubectl describe pod image-test -n broken-apps
+# Look for Events section:
+# - Type: Warning | Reason: Failed | Message: Error response from daemon...
+```
+
+### Solution
+
+**Approach 1: Patch (Fastest — 30 seconds)**
+
+```bash
+kubectl patch pod image-test -n broken-apps -p \
+  '{"spec":{"containers":[{"name":"app","image":"nginx:1.25"}]}}'
+
+kubectl get pod image-test -n broken-apps
+# Status should change: ImagePullBackOff → Running
+```
+
+**Approach 2: Export, Edit, Recreate** (safer for complex changes)
+
+```bash
+kubectl get pod image-test -n broken-apps -o yaml > image-test.yaml
+# Edit: image: private-registry/app:v2.0 → image: nginx:1.25
+kubectl delete pod image-test -n broken-apps
+kubectl apply -f image-test.yaml
+```
+
+### Verification
+
+```bash
+kubectl logs image-test -n broken-apps
+# No "image not found" errors
+```
+
+⚠️ **Common pitfalls**: Misspelled image names, private registry without secrets
+
+---
+
+## Bonus: Question 17B — Debugging ConfigMap Key Mismatch [Debugging Skill]
+
+### Problem Diagnosis
+
+App logs show: `"ConfigMap key DATABASE_URL not found"` → Mismatch between Pod spec and actual ConfigMap keys.
+
+**Step 1: Check actual ConfigMap**
+
+```bash
+kubectl get configmap app-config -n app-errors -o yaml
+# data:
+#   DB_URL: "postgres://..."  # Key exists, not DATABASE_URL!
+```
+
+**Step 2: Find the Deployment using it**
+
+```bash
+kubectl describe deployment data-processor -n app-errors | grep -A 5 "env:\|valueFrom"
+```
+
+### Solution
+
+**Edit Deployment → Fix Key Name**
+
+```bash
+kubectl edit deployment data-processor -n app-errors
+```
+
+Change:
+```yaml
+# FROM:
+env:
+- name: DATABASE_URL
+  valueFrom:
+    configMapKeyRef:
+      key: DATABASE_URL  # ❌ Doesn't exist
+
+# TO:
+env:
+- name: DATABASE_URL
+  valueFrom:
+    configMapKeyRef:
+      key: DB_URL  # ✅ Matches ConfigMap
+```
+
+### Verification
+
+```bash
+kubectl rollout restart deployment/data-processor -n app-errors
+kubectl logs deployment/data-processor -n app-errors
+# Check: No "key not found" errors
+```
+
+---
+
 ## Weak Area Review
 
 If you scored below 50% in any domain, review:

mock-exams/MOCK-EXAM-01.md

@@ -265,6 +265,32 @@ Create a StatefulSet named `db-app` in namespace `advanced` with:
 
 ---
 
+## Question 16+ (Bonus Debugging Scenarios) — For Practice Beyond Exam
+
+### Question 16B [Debugging] — Broken Pod with Image Pull Error
+
+**Context:** `kubectl config use-context k8s-cluster1`  
+**Namespace:** `broken-apps`
+
+**Task:**  
+A Pod named `image-test` in namespace `broken-apps` is stuck in `ImagePullBackOff` state. The Pod spec references image `private-registry/app:v2.0` but you need to use the public image `nginx:1.25` instead.
+
+Troubleshoot and fix without recreating the Pod. Hint: Check pod events with `kubectl describe pod image-test -n broken-apps`
+
+---
+
+### Question 17B [Debugging] — ConfigMap Key Mismatch
+
+**Context:** `kubectl config use-context k8s-cluster2`  
+**Namespace:** `app-errors`
+
+**Task:**  
+Deployment `data-processor` in namespace `app-errors` is running but logs show: `Error: ConfigMap key DATABASE_URL not found`. The ConfigMap `app-config` exists with key `DB_URL` (not `DATABASE_URL`). Fix the Deployment to use the correct key without recreating pods.
+
+Verification: `kubectl logs -n app-errors <pod> | grep success`
+
+---
+
 ## Scoring Sheet
 
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