Pre-Deployment Task Scripts

Pre-Deployment scripts execute before deployment operations begin, providing validation, preparation, and safeguarding measures. These scripts can prevent deployments that don't meet requirements or could cause issues.

Overview

Pre-Deployment tasks ensure: - Readiness Validation: Target environment prepared - Prerequisite Checks: Required conditions met - Backup Creation: Safeguard existing data - Conflict Detection: Identify potential issues - Authorization: Verify deployment approval - Resource Availability: Ensure sufficient resources

Figure: Pre-deployment validation and preparation flow

When to Use

Pre-Deployment scripts are critical for: - Production deployment validation - Creating backup points - Checking maintenance windows - Verifying approvals - Ensuring target compatibility - Preventing conflicting deployments

Key Characteristics

• Blocking: Can prevent deployment
• Synchronous: Deployment waits
• Validation-focused: Check prerequisites
• Safety-oriented: Prevent issues
• Environment-aware: Different per environment

Common Pre-Deployment Patterns

Pattern 1: Complete Environment Validation

DECLARE
  c_script_name CONSTANT VARCHAR2(100) := 'PRE_DEPLOY_VALIDATION';
  l_target_status VARCHAR2(50);
  l_active_users NUMBER;
  l_running_jobs NUMBER;
  l_disk_space NUMBER;

  PROCEDURE log(p_msg VARCHAR2) IS
  BEGIN
    ew_debug.log(p_text      => p_msg,
                 p_source_ref => c_script_name);
  END;

  FUNCTION check_target_readiness RETURN BOOLEAN IS
  BEGIN
    -- Check application status
    SELECT status INTO l_target_status
    FROM ew_applications
    WHERE app_name = ew_lb_api.g_target_app;

    IF l_target_status NOT IN ('ACTIVE', 'MAINTENANCE') THEN
      ew_lb_api.g_message := 'Target application status is ' || 
                              l_target_status || ', expected ACTIVE or MAINTENANCE';
      RETURN FALSE;
    END IF;

    -- Check for active users
    SELECT COUNT(*) INTO l_active_users
    FROM ew_user_sessions
    WHERE app_name = ew_lb_api.g_target_app
    AND last_activity > SYSDATE - 1/24; -- Active in last hour

    IF l_active_users > 0 AND ew_lb_api.g_deployment_type = 'FULL' THEN
      ew_lb_api.g_message := l_active_users || 
                              ' active users detected. Cannot perform FULL deployment';
      RETURN FALSE;
    END IF;

    -- Check running jobs
    SELECT COUNT(*) INTO l_running_jobs
    FROM ew_scheduled_jobs
    WHERE app_name = ew_lb_api.g_target_app
    AND status = 'RUNNING';

    IF l_running_jobs > 0 THEN
      ew_lb_api.g_message := l_running_jobs || 
                              ' jobs are running. Wait for completion before deployment';
      RETURN FALSE;
    END IF;

    -- Check disk space
    l_disk_space := get_available_disk_space();

    IF l_disk_space < 1000 THEN -- Less than 1GB
      ew_lb_api.g_message := 'Insufficient disk space: ' || 
                              l_disk_space || 'MB available';
      RETURN FALSE;
    END IF;

    RETURN TRUE;
  END;

BEGIN
  -- Initialize
  ew_lb_api.g_status := ew_lb_api.g_success;
  ew_lb_api.g_message := NULL;

  log('Starting pre-deployment validation');
  log('Deployment ID: ' || ew_lb_api.g_deployment_id);
  log('Target App: ' || ew_lb_api.g_target_app);
  log('Deployment Type: ' || ew_lb_api.g_deployment_type);

  -- Perform comprehensive validation
  IF NOT check_target_readiness() THEN
    ew_lb_api.g_status := ew_lb_api.g_error;
    log('Validation failed: ' || ew_lb_api.g_message);
    RETURN;
  END IF;

  log('Pre-deployment validation completed successfully');

EXCEPTION
  WHEN OTHERS THEN
    ew_lb_api.g_status := ew_lb_api.g_error;
    ew_lb_api.g_message := 'Pre-deployment validation error: ' || SQLERRM;
    log('Error: ' || SQLERRM);
END;

Pattern 2: Automated Backup Creation

DECLARE
  c_script_name CONSTANT VARCHAR2(100) := 'PRE_DEPLOY_BACKUP';
  l_backup_id NUMBER;
  l_backup_name VARCHAR2(200);
  l_backup_size NUMBER;

  PROCEDURE log(p_msg VARCHAR2) IS
  BEGIN
    ew_debug.log(p_text      => p_msg,
                 p_source_ref => c_script_name);
  END;

  PROCEDURE create_backup IS
  BEGIN
    -- Generate backup name
    l_backup_name := ew_lb_api.g_target_app || '_' || 
                     TO_CHAR(SYSDATE, 'YYYYMMDD_HH24MISS') || '_' ||
                     ew_lb_api.g_deployment_id;

    log('Creating backup: ' || l_backup_name);

    -- Create metadata backup
    ew_backup.create_metadata_backup(
      p_app_name    => ew_lb_api.g_target_app,
      p_backup_name => l_backup_name,
      p_backup_type => 'PRE_DEPLOYMENT',
      p_include_data => CASE 
                          WHEN ew_lb_api.g_target_app LIKE '%PROD%' 
                          THEN 'Y' 
                          ELSE 'N' 
                        END,
      x_backup_id   => l_backup_id
    );

    -- Verify backup
    SELECT backup_size_mb
    INTO l_backup_size
    FROM ew_backups
    WHERE backup_id = l_backup_id;

    IF l_backup_size = 0 THEN
      RAISE_APPLICATION_ERROR(-20001, 'Backup creation failed - zero size');
    END IF;

    log('Backup created successfully. ID: ' || l_backup_id || 
        ', Size: ' || l_backup_size || 'MB');

    -- Store backup reference for potential rollback
    INSERT INTO deployment_backups (
      deployment_id,
      backup_id,
      backup_name,
      created_date
    ) VALUES (
      ew_lb_api.g_deployment_id,
      l_backup_id,
      l_backup_name,
      SYSDATE
    );

    COMMIT;

  EXCEPTION
    WHEN OTHERS THEN
      log('Backup creation failed: ' || SQLERRM);
      RAISE;
  END;

BEGIN
  ew_lb_api.g_status := ew_lb_api.g_success;
  ew_lb_api.g_message := NULL;

  -- Only create backup for production or if requested
  IF ew_lb_api.g_target_app LIKE '%PROD%' OR
     get_deployment_param('CREATE_BACKUP') = 'Y' THEN

    create_backup();

    ew_lb_api.g_message := 'Backup created: ' || l_backup_name;
  ELSE
    log('Backup skipped for non-production environment');
  END IF;

EXCEPTION
  WHEN OTHERS THEN
    ew_lb_api.g_status := ew_lb_api.g_error;
    ew_lb_api.g_message := 'Backup creation failed: ' || SQLERRM;
    log('Error: ' || SQLERRM);
END;

Pattern 3: Maintenance Window Verification

DECLARE
  c_script_name CONSTANT VARCHAR2(100) := 'CHECK_MAINTENANCE_WINDOW';
  l_current_time DATE := SYSDATE;
  l_window_start DATE;
  l_window_end DATE;
  l_is_emergency VARCHAR2(1);

  PROCEDURE log(p_msg VARCHAR2) IS
  BEGIN
    ew_debug.log(p_text      => p_msg,
                 p_source_ref => c_script_name);
  END;

BEGIN
  ew_lb_api.g_status := ew_lb_api.g_success;

  -- Check if emergency deployment
  l_is_emergency := get_deployment_param('EMERGENCY_DEPLOYMENT');

  IF l_is_emergency = 'Y' THEN
    log('Emergency deployment - bypassing maintenance window check');

    -- Log emergency deployment
    INSERT INTO emergency_deployments_log (
      deployment_id,
      approver,
      reason,
      deployment_date
    ) VALUES (
      ew_lb_api.g_deployment_id,
      ew_lb_api.g_user_id,
      get_deployment_param('EMERGENCY_REASON'),
      SYSDATE
    );

    RETURN;
  END IF;

  -- Get maintenance window for target environment
  BEGIN
    SELECT window_start, window_end
    INTO l_window_start, l_window_end
    FROM maintenance_windows
    WHERE app_name = ew_lb_api.g_target_app
    AND TRUNC(l_current_time) = TRUNC(window_date)
    AND active_flag = 'Y';

    -- Check if current time is within window
    IF l_current_time NOT BETWEEN l_window_start AND l_window_end THEN
      ew_lb_api.g_status := ew_lb_api.g_error;
      ew_lb_api.g_message := 
        'Deployment only allowed during maintenance window: ' ||
        TO_CHAR(l_window_start, 'HH24:MI') || ' - ' ||
        TO_CHAR(l_window_end, 'HH24:MI');
      log('Outside maintenance window');
    ELSE
      log('Within maintenance window');
    END IF;

  EXCEPTION
    WHEN NO_DATA_FOUND THEN
      -- No maintenance window defined
      IF ew_lb_api.g_target_app LIKE '%PROD%' THEN
        ew_lb_api.g_status := ew_lb_api.g_error;
        ew_lb_api.g_message := 
          'No maintenance window defined for production deployment';
        log('No maintenance window found');
      ELSE
        log('No maintenance window required for non-production');
      END IF;
  END;

END;

Pattern 4: Conflict Detection

DECLARE
  c_script_name CONSTANT VARCHAR2(100) := 'DETECT_CONFLICTS';
  l_conflict_count NUMBER;
  l_conflict_details VARCHAR2(4000);

  PROCEDURE log(p_msg VARCHAR2) IS
  BEGIN
    ew_debug.log(p_text      => p_msg,
                 p_source_ref => c_script_name);
  END;

BEGIN
  ew_lb_api.g_status := ew_lb_api.g_success;

  -- Check for concurrent deployments
  SELECT COUNT(*)
  INTO l_conflict_count
  FROM active_deployments
  WHERE target_app = ew_lb_api.g_target_app
  AND deployment_id != ew_lb_api.g_deployment_id
  AND status IN ('RUNNING', 'PENDING');

  IF l_conflict_count > 0 THEN
    ew_lb_api.g_status := ew_lb_api.g_error;
    ew_lb_api.g_message := 
      'Another deployment is in progress for ' || ew_lb_api.g_target_app;
    log('Concurrent deployment detected');
    RETURN;
  END IF;

  -- Check for metadata conflicts
  FOR conflict IN (
    SELECT member_name, 
           'Modified in target after export' as conflict_type
    FROM deployment_members dm
    WHERE dm.deployment_id = ew_lb_api.g_deployment_id
    AND EXISTS (
      SELECT 1 FROM ew_members m
      WHERE m.app_name = ew_lb_api.g_target_app
      AND m.member_name = dm.member_name
      AND m.last_modified > dm.export_date
    )
  ) LOOP
    l_conflict_details := l_conflict_details || 
                          conflict.member_name || ': ' || 
                          conflict.conflict_type || '; ';
  END LOOP;

  IF l_conflict_details IS NOT NULL THEN
    ew_lb_api.g_status := ew_lb_api.g_error;
    ew_lb_api.g_message := 
      'Metadata conflicts detected: ' || l_conflict_details;
    log('Conflicts: ' || l_conflict_details);
  END IF;

END;

Pattern 5: Approval Verification

DECLARE
  c_script_name CONSTANT VARCHAR2(100) := 'VERIFY_DEPLOYMENT_APPROVAL';
  l_approval_required VARCHAR2(1);
  l_approval_status VARCHAR2(50);
  l_approver VARCHAR2(100);

BEGIN
  ew_lb_api.g_status := ew_lb_api.g_success;

  -- Determine if approval required
  l_approval_required := CASE
    WHEN ew_lb_api.g_target_app LIKE '%PROD%' THEN 'Y'
    WHEN ew_lb_api.g_deployment_type = 'FULL' THEN 'Y'
    WHEN is_sensitive_metadata() THEN 'Y'
    ELSE 'N'
  END;

  IF l_approval_required = 'Y' THEN
    -- Check for approval
    BEGIN
      SELECT approval_status, approver
      INTO l_approval_status, l_approver
      FROM deployment_approvals
      WHERE deployment_id = ew_lb_api.g_deployment_id;

      IF l_approval_status != 'APPROVED' THEN
        ew_lb_api.g_status := ew_lb_api.g_error;
        ew_lb_api.g_message := 
          'Deployment requires approval. Current status: ' || 
          l_approval_status;
      ELSE
        ew_debug.log('Deployment approved by: ' || l_approver);
      END IF;

    EXCEPTION
      WHEN NO_DATA_FOUND THEN
        ew_lb_api.g_status := ew_lb_api.g_error;
        ew_lb_api.g_message := 
          'Deployment requires approval. No approval record found.';
    END;
  END IF;

END;

Best Practices

1. Fast Fail Validation

-- Check simplest conditions first
IF quick_check_fails THEN
  ew_lb_api.g_status := ew_lb_api.g_error;
  RETURN; -- Don't continue
END IF;

-- Then more complex checks
IF complex_validation_fails THEN
  -- ...
END IF;

2. Comprehensive Logging

-- Log all validation steps
log('=== Pre-Deployment Validation ===');
log('Step 1: Checking application status - ' || l_status);
log('Step 2: Verifying disk space - ' || l_space || 'MB');
log('Step 3: Creating backup - ' || l_backup_name);
log('=== Validation Complete ===');

3. Rollback Preparation

-- Store rollback information
INSERT INTO deployment_rollback_info (
  deployment_id,
  backup_id,
  original_state,
  rollback_script
) VALUES (
  ew_lb_api.g_deployment_id,
  l_backup_id,
  capture_current_state(),
  generate_rollback_script()
);

4. Clear Error Messages

-- Provide actionable feedback
ew_lb_api.g_message := 
  'Cannot deploy: 5 users are actively working in ' || 
  ew_lb_api.g_target_app || '. ' ||
  'Please notify users and retry after they log out, or ' ||
  'schedule deployment for maintenance window (22:00-02:00).';

Testing Pre-Deployment Scripts

Test Scenarios

Scenario	Test Case	Expected Result
Ready Environment	All checks pass	Deployment proceeds
Active Users	Users logged in	Block deployment
No Backup Space	Disk full	Block with space error
Outside Window	Wrong time	Block with window info
No Approval	Missing approval	Block with approval request
Concurrent Deploy	Another running	Block with conflict error

Performance Considerations

• Timeout Handling: Set reasonable timeouts
• Parallel Checks: Run independent validations concurrently
• Cache Results: Cache environment status briefly
• Quick Checks First: Fail fast on simple validations

Next Steps

• Post-Deployment Tasks - After deployment scripts
• Deployment Overview - General deployment concepts
• API Reference - Supporting functions

---

Critical

Pre-deployment scripts are your last line of defense against problematic deployments. Ensure they are comprehensive, especially for production environments.