Feature/lab7

.github/pull_request_template.md

@@ -0,0 +1,6 @@
+## Goal
+## Changes
+## Testing
+- [ ] Clear, descriptive PR title
+- [ ] Documentation updated
+- [ ] No secrets committed

healthcheck.sh

@@ -0,0 +1,13 @@
+#!/bin/bash
+# healthcheck.sh - Monitor GitOps sync health
+
+DESIRED_MD5=$(md5sum desired-state.txt | awk '{print $1}')
+CURRENT_MD5=$(md5sum current-state.txt | awk '{print $1}')
+
+if [ "$DESIRED_MD5" != "$CURRENT_MD5" ]; then
+    echo "$(date) - ❌ CRITICAL: State mismatch detected!" | tee -a health.log
+    echo "  Desired MD5: $DESIRED_MD5" | tee -a health.log
+    echo "  Current MD5: $CURRENT_MD5" | tee -a health.log
+else
+    echo "$(date) - ✅ OK: States synchronized" | tee -a health.log
+fi

labs/submission7.md

@@ -0,0 +1,259 @@
+### Task 1
+
+#### 1.1: Setup Desired State Configuration
+
+```bash
+$ echo "version: 1.0" > desired-state.txt
+$ echo "app: myapp" >> desired-state.txt
+$ echo "replicas: 3" >> desired-state.txt
+
+$ cp desired-state.txt current-state.txt
+$ echo "Initial state synchronized"
+Initial state synchronized
+```
+
+Initial `desired-state.txt`:
+
+```bash
+version: 1.0
+app: myapp
+replicas: 3
+```
+
+Initial `current-state.txt`:
+
+```bash
+version: 1.0
+app: myapp
+replicas: 3
+```
+
+#### 1.2: Create Reconciliation Loop
+
+Created `reconcile.sh` and made it executable:
+
+```bash
+$ chmod +x reconcile.sh
+```
+
+#### 1.3: Test Manual Drift Detection
+
+I changed the current state manually:
+
+```bash
+$ echo "version: 2.0" > current-state.txt
+$ echo "app: myapp" >> current-state.txt
+$ echo "replicas: 5" >> current-state.txt
+```
+
+Then ran reconciliation:
+
+```bash
+$ ./reconcile.sh
+Sun May 10 12:55:01 MSK 2026 - ⚠️  DRIFT DETECTED!
+Reconciling current state with desired state...
+Sun May 10 12:55:01 MSK 2026 - ✅ Reconciliation complete
+```
+
+After reconciliation:
+
+```bash
+$ diff desired-state.txt current-state.txt
+```
+
+```bash
+$ cat current-state.txt
+version: 1.0
+app: myapp
+replicas: 3
+```
+
+#### 1.4: Automated Continuous Reconciliation
+
+Initially `watch` was not installed, so I installed it with Homebrew and then started the loop:
+
+```bash
+$ watch -n 5 ./reconcile.sh
+```
+
+Output from continuous reconciliation loop after triggering drift:
+
+```bash
+Every 5.0s: ./reconcile.sh                                                            TomatoComputer.local: Sun May 10 12:57:52 2026
+
+Sun May 10 12:57:52 MSK 2026 - ⚠️  DRIFT DETECTED!
+Reconciling current state with desired state...
+Sun May 10 12:57:52 MSK 2026 - ✅ Reconciliation complete
+```
+
+This shows that the loop detected drift and automatically restored the desired state.
+
+### Observations and Analysis
+
+The GitOps reconciliation loop continuously compares the current state with the desired state stored in Git. If drift appears, the loop detects it and replaces the current state with the desired one. This prevents configuration drift because any manual or unintended change is overwritten during the next reconciliation cycle.
+
+Declarative configuration is better than imperative commands in production because it defines the final expected state instead of a sequence of manual actions. This makes changes easier to review, version, repeat, and recover.
+
+### Task 2
+
+#### 2.1: Create Health Check Script
+
+Contents of `healthcheck.sh`:
+
+```bash
+#!/bin/bash
+# healthcheck.sh - Monitor GitOps sync health
+
+DESIRED_MD5=$(md5sum desired-state.txt | awk '{print $1}')
+CURRENT_MD5=$(md5sum current-state.txt | awk '{print $1}')
+
+if [ "$DESIRED_MD5" != "$CURRENT_MD5" ]; then
+    echo "$(date) - ❌ CRITICAL: State mismatch detected!" | tee -a health.log
+    echo "  Desired MD5: $DESIRED_MD5" | tee -a health.log
+    echo "  Current MD5: $CURRENT_MD5" | tee -a health.log
+else
+    echo "$(date) - ✅ OK: States synchronized" | tee -a health.log
+fi
+```
+
+Made it executable:
+
+```bash
+$ chmod +x healthcheck.sh
+```
+
+#### 2.2: Test Health Monitoring
+
+Healthy state:
+
+```bash
+$ ./healthcheck.sh
+$ cat health.log
+Sun May 10 13:02:36 MSK 2026 - ✅ OK: States synchronized
+Sun May 10 13:02:36 MSK 2026 - ✅ OK: States synchronized
+```
+
+Then I simulated configuration drift:
+
+```bash
+$ echo "unapproved-change: true" >> current-state.txt
+```
+
+Health check on drifted state:
+
+```bash
+$ ./healthcheck.sh
+$ cat health.log
+Sun May 10 13:02:46 MSK 2026 - ❌ CRITICAL: State mismatch detected!
+  Desired MD5: a15a1a4f965ecd8f9e23a33a6b543155
+  Current MD5: 48168ff3ab5ffc0214e81c7e2ee356f5
+Sun May 10 13:02:36 MSK 2026 - ✅ OK: States synchronized
+Sun May 10 13:02:46 MSK 2026 - ❌ CRITICAL: State mismatch detected!
+  Desired MD5: a15a1a4f965ecd8f9e23a33a6b543155
+  Current MD5: 48168ff3ab5ffc0214e81c7e2ee356f5
+```
+
+Fix drift and verify:
+
+```bash
+$ ./reconcile.sh
+$ ./healthcheck.sh
+$ cat health.log
+Sun May 10 13:02:52 MSK 2026 - ⚠️  DRIFT DETECTED!
+Reconciling current state with desired state...
+Sun May 10 13:02:52 MSK 2026 - ✅ Reconciliation complete
+Sun May 10 13:02:52 MSK 2026 - ✅ OK: States synchronized
+Sun May 10 13:02:36 MSK 2026 - ✅ OK: States synchronized
+Sun May 10 13:02:46 MSK 2026 - ❌ CRITICAL: State mismatch detected!
+  Desired MD5: a15a1a4f965ecd8f9e23a33a6b543155
+  Current MD5: 48168ff3ab5ffc0214e81c7e2ee356f5
+Sun May 10 13:02:52 MSK 2026 - ✅ OK: States synchronized
+```
+
+#### 2.3: Continuous Health Monitoring
+
+Contents of `monitor.sh`:
+
+```bash
+#!/bin/bash
+# monitor.sh - Combined reconciliation and health monitoring
+
+echo "Starting GitOps monitoring..."
+for i in {1..10}; do
+    echo "\n--- Check #$i ---"
+    ./healthcheck.sh
+    ./reconcile.sh
+    sleep 3
+done
+```
+
+Made it executable:
+
+```bash
+$ chmod +x monitor.sh
+```
+
+Output from `monitor.sh`:
+
+```bash
+$ ./monitor.sh
+Starting GitOps monitoring...
+\n--- Check #1 ---
+Sun May 10 13:03:14 MSK 2026 - ✅ OK: States synchronized
+Sun May 10 13:03:14 MSK 2026 - ✅ States synchronized
+\n--- Check #2 ---
+Sun May 10 13:03:17 MSK 2026 - ✅ OK: States synchronized
+Sun May 10 13:03:17 MSK 2026 - ✅ States synchronized
+\n--- Check #3 ---
+Sun May 10 13:03:20 MSK 2026 - ✅ OK: States synchronized
+Sun May 10 13:03:20 MSK 2026 - ✅ States synchronized
+\n--- Check #4 ---
+Sun May 10 13:03:23 MSK 2026 - ✅ OK: States synchronized
+Sun May 10 13:03:23 MSK 2026 - ✅ States synchronized
+\n--- Check #5 ---
+Sun May 10 13:03:26 MSK 2026 - ✅ OK: States synchronized
+Sun May 10 13:03:26 MSK 2026 - ✅ States synchronized
+\n--- Check #6 ---
+Sun May 10 13:03:29 MSK 2026 - ✅ OK: States synchronized
+Sun May 10 13:03:29 MSK 2026 - ✅ States synchronized
+\n--- Check #7 ---
+Sun May 10 13:03:32 MSK 2026 - ✅ OK: States synchronized
+Sun May 10 13:03:32 MSK 2026 - ✅ States synchronized
+\n--- Check #8 ---
+Sun May 10 13:03:35 MSK 2026 - ✅ OK: States synchronized
+Sun May 10 13:03:35 MSK 2026 - ✅ States synchronized
+\n--- Check #9 ---
+Sun May 10 13:03:38 MSK 2026 - ✅ OK: States synchronized
+Sun May 10 13:03:38 MSK 2026 - ✅ States synchronized
+\n--- Check #10 ---
+Sun May 10 13:03:41 MSK 2026 - ✅ OK: States synchronized
+Sun May 10 13:03:41 MSK 2026 - ✅ States synchronized
+```
+
+Complete `health.log`:
+
+```bash
+$ cat health.log
+Sun May 10 13:02:36 MSK 2026 - ✅ OK: States synchronized
+Sun May 10 13:02:46 MSK 2026 - ❌ CRITICAL: State mismatch detected!
+  Desired MD5: a15a1a4f965ecd8f9e23a33a6b543155
+  Current MD5: 48168ff3ab5ffc0214e81c7e2ee356f5
+Sun May 10 13:02:52 MSK 2026 - ✅ OK: States synchronized
+Sun May 10 13:03:14 MSK 2026 - ✅ OK: States synchronized
+Sun May 10 13:03:17 MSK 2026 - ✅ OK: States synchronized
+Sun May 10 13:03:20 MSK 2026 - ✅ OK: States synchronized
+Sun May 10 13:03:23 MSK 2026 - ✅ OK: States synchronized
+Sun May 10 13:03:26 MSK 2026 - ✅ OK: States synchronized
+Sun May 10 13:03:29 MSK 2026 - ✅ OK: States synchronized
+Sun May 10 13:03:32 MSK 2026 - ✅ OK: States synchronized
+Sun May 10 13:03:35 MSK 2026 - ✅ OK: States synchronized
+Sun May 10 13:03:38 MSK 2026 - ✅ OK: States synchronized
+Sun May 10 13:03:41 MSK 2026 - ✅ OK: States synchronized
+```
+
+### Observations and Analysis
+
+Checksums (MD5) help detect configuration changes because they give a compact fingerprint of file contents. If the desired and current files are different, their MD5 values will also be different, so the script can quickly detect drift.
+
+This is similar to GitOps tools like ArgoCD showing sync status. In both cases, the system compares the actual state with the desired state and reports whether they match. My script prints `OK` or `CRITICAL`, while ArgoCD would show synced or out-of-sync status in its UI.
+

monitor.sh

@@ -0,0 +1,10 @@
+#!/bin/bash
+# monitor.sh - Combined reconciliation and health monitoring
+
+echo "Starting GitOps monitoring..."
+for i in {1..10}; do
+    echo "\n--- Check #$i ---"
+    ./healthcheck.sh
+    ./reconcile.sh
+    sleep 3
+done

reconcile.sh

@@ -0,0 +1,15 @@
+#!/bin/bash
+# reconcile.sh - GitOps reconciliation loop
+
+DESIRED=$(cat desired-state.txt)
+CURRENT=$(cat current-state.txt)
+
+if [ "$DESIRED" != "$CURRENT" ]; then
+    echo "$(date) - ⚠️  DRIFT DETECTED!"
+    echo "Reconciling current state with desired state..."
+    cp desired-state.txt current-state.txt
+    echo "$(date) - ✅ Reconciliation complete"
+else
+    echo "$(date) - ✅ States synchronized"
+fi
+