feat: [#12] complete VM integration testing with MySQL x86-64-v2 CPU fix

- Updated VM CPU model to host-model for x86-64-v2 instruction set support
- Completed VM integration testing phase of MySQL migration
- Fixed bash quoting in integration testing guide to avoid history expansion
- Documented MySQL CPU requirement issue and technical solution
- Verified all services running and healthy on VM with MySQL backend
- Smoke tested tracker API endpoints successfully

Author: josecelano

docs/guides/integration-testing-guide.md

@@ -93,15 +93,15 @@ echo "=== Verifying Clean State ==="
 
 # Check VMs
 virsh list --all | grep torrust-tracker-demo && \
-  echo "❌ VM still exists!" || echo "✅ No VM conflicts"
+  echo '❌ VM still exists!' || echo '✅ No VM conflicts'
 
 # Check volumes in user-default pool
 virsh vol-list user-default 2>/dev/null | grep torrust-tracker-demo && \
-  echo "❌ Volumes still exist!" || echo "✅ No volume conflicts"
+  echo '❌ Volumes still exist!' || echo '✅ No volume conflicts'
 
 # Check OpenTofu state
 ls infrastructure/terraform/terraform.tfstate* 2>/dev/null && \
-  echo "❌ State files still exist!" || echo "✅ No state file conflicts"
+  echo '❌ State files still exist!' || echo '✅ No state file conflicts'
 ```
 
 **Expected Output**: All checks should show "✅" (no conflicts).
@@ -120,7 +120,7 @@ virsh vol-delete torrust-tracker-demo.qcow2 user-default
 
 # Verify cleanup
 virsh vol-list user-default 2>/dev/null | grep torrust-tracker-demo && \
-  echo "❌ Volumes still exist!" || echo "✅ No volume conflicts"
+  echo '❌ Volumes still exist!' || echo '✅ No volume conflicts'
 ```
 
 **Expected Output**: Should show "✅ No volume conflicts" after manual cleanup.
@@ -392,8 +392,8 @@ while true; do
     echo "$(date): Testing SSH to $VM_IP..."
     if timeout 10 ssh -o StrictHostKeyChecking=no \
        -o ConnectTimeout=10 torrust@$VM_IP \
-       "echo 'SSH works!'" 2>/dev/null; then
-        echo "✅ SSH connection successful!"
+       'echo "SSH works!"' 2>/dev/null; then
+        echo '✅ SSH connection successful!'
         break
     fi
     echo "⏳ Cloud-init still running... waiting 30 seconds"

docs/issues/12-use-mysql-instead-of-sqlite-by-default.md

@@ -235,9 +235,11 @@ cd application/
 
 4. **VM Integration Testing**:
 
-   - **Status**: ⬜ **Pending**
+   - **Status**: ✅ **Completed** (2025-07-08)
    - **Description**: Deploy the complete stack on a local VM to test the full
      infrastructure integration.
+   - **Solution**: MySQL 8.0 x86-64-v2 CPU requirement resolved by configuring VM with
+     `host-model` CPU mode to enable modern instruction sets.
 
    ```bash
    # From the repository root
@@ -246,6 +248,19 @@ cd application/
    # Run smoke tests from the smoke testing guide
    ```
 
+   **Results**:
+
+   - ✅ All Docker containers running successfully
+   - ✅ MySQL container: `Up 48 minutes (healthy)` - no more restart loops
+   - ✅ Tracker container: `Up 48 minutes (healthy)` - connected to MySQL
+   - ✅ All services responding to health checks
+
+   **Technical Solution**:
+
+   - **Issue**: MySQL 8.0 Docker image requires x86-64-v2 CPU instruction set
+   - **Fix**: Updated `infrastructure/terraform/main.tf` to use `host-model` CPU mode
+   - **Result**: VM CPU now supports x86-64-v2 instructions required by MySQL 8.0
+
 ### Phase 2: Documentation and Cleanup
 
 **Status**: ⬜ **Pending**
@@ -269,7 +284,7 @@ remove any outdated SQLite references.
 - [x] Docker Compose service dependencies updated
 - [x] Local functionality testing passed
 - [x] Local data persistence testing passed
-- [ ] VM integration testing passed
+- [x] VM integration testing passed
 - [ ] All documentation updated
 - [ ] Old SQLite configurations removed or documented as legacy
 - [ ] Final PR reviewed and approved

infrastructure/terraform/main.tf

@@ -106,7 +106,12 @@ resource "libvirt_domain" "vm" {
 
   cloudinit = libvirt_cloudinit_disk.commoninit.id
 
-
+  # CPU configuration - use a modern CPU model that supports x86-64-v2
+  # Enable modern CPU model for x86-64-v2 instruction set support (required by MySQL 8.0)
+  # Reference: https://github.com/docker-library/mysql/issues/1055
+  cpu {
+    mode = "host-model"
+  }
 
   disk {
     volume_id = libvirt_volume.vm_disk.id