Added container disk usage

src/collectors/container_collector.py

@@ -59,6 +59,18 @@ class ContainerCollector(BaseCollector):
                     'timestamp': timestamp
                 })
                 
+                # Disk usage metrics (available for all containers)
+                try:
+                    disk_usage = self._get_container_disk_usage(container)
+                    if disk_usage is not None:
+                        metrics.append({
+                            'name': f'containers.{container_name}.disk_usage_bytes',
+                            'value': disk_usage,
+                            'timestamp': timestamp
+                        })
+                except Exception as e:
+                    print(f"Warning: Could not collect disk usage for {container_name}: {e}")
+                
                 # Only collect resource metrics for running containers
                 if state == 'running':
                     try:
@@ -226,3 +238,27 @@ class ContainerCollector(BaseCollector):
             print(f"Warning: Error getting I/O metrics: {e}")
         
         return metrics
+    
+    def _get_container_disk_usage(self, container) -> int:
+        """
+        Get the disk usage for a container in bytes.
+        This includes the writable layer size (SizeRw) and root filesystem size (SizeRootFs).
+        """
+        try:
+            # Reload container to get latest attributes with size information
+            container.reload()
+            attrs = container.attrs
+            
+            # SizeRw: Size of files that have been created or changed
+            size_rw = attrs.get('SizeRw', 0)
+            
+            # SizeRootFs: Total size of container filesystem (read-only + writable layers)
+            size_rootfs = attrs.get('SizeRootFs', 0)
+            
+            # Return the total size (SizeRootFs includes SizeRw)
+            # If SizeRootFs is not available, fall back to SizeRw
+            return size_rootfs if size_rootfs > 0 else size_rw
+            
+        except Exception as e:
+            print(f"Warning: Error getting disk usage: {e}")
+            return None