Implement Docker monitoring system to address isolation level visibility gaps

[Copilot]

This PR implements a comprehensive monitoring system that addresses the "Docker monitoring problem" by providing visibility across process, container, and host isolation levels, bridging the monitoring gap identified in containerized environments.

Problem

The Docker monitoring problem occurs due to isolation between different abstraction levels in containerized environments. As shown in the monitoring architecture, there's a critical "Gap" between monitoring capabilities at different isolation levels:

• Process Level: Limited visibility into individual processes within containers
• Container Level: Isolated view of container metrics without host context
• Host Level: System-wide metrics without container-specific correlation

This creates blind spots where issues can occur across isolation boundaries without proper visibility.

Solution

The implementation provides multi-level monitoring that maps directly to the isolation characteristics:

Aspect	Process	Container	Host
Spec	Source	Dockerfile	Kickstart
On disk	.TEXT	/var/lib/docker	/
In memory	PID	Container ID	Hostname
In network	Socket	veth*	eth*
Runtime context	server core	host	data center
Isolation	moderate	private OS view	full

Key Features

Multi-Level Monitoring

• ProcessMonitor: Tracks individual processes with PID, memory usage, CPU stats, and socket information
• ContainerMonitor: Monitors containers with namespace info, veth interfaces, and Docker storage paths
• HostMonitor: System-wide metrics including hostname, memory, CPU, disk, and network interfaces

CLI Commands

# Monitor different isolation levels
./basic-docker monitor host                    # Host-level system metrics
./basic-docker monitor process <pid>           # Process-specific monitoring  
./basic-docker monitor container <container-id> # Container metrics and isolation
./basic-docker monitor all                     # Aggregated multi-level view

# Gap analysis and correlation
./basic-docker monitor gap                     # Identify monitoring gaps
./basic-docker monitor correlation <container-id> # Show level correlations

Gap Analysis

The system identifies and addresses three categories of monitoring gaps:

• Process to Container: PID mapping, namespace isolation visibility, resource enforcement
• Container to Host: Network isolation vs visibility, filesystem overlays, resource allocation
• Cross-Level: Transaction tracing, performance correlation, security events

Example Usage

$ ./basic-docker monitor correlation container-1234
Level Correlation Table (Based on Docker Monitoring Problem):
-------------------------------------------------------------
Aspect          | Process              | Container            | Host                
--------------------------------------------------------------------------------
Spec            | Source               | Dockerfile           | Kickstart           
On disk         | .TEXT                | /var/lib/docker/...  | /                   
In memory       | PID 1234             | container-1234       | hostname             
In network      | Socket               | veth0a1b2c3d         | eth0                
Runtime context | server core          | host                 | data center         
Isolation       | moderate             | private OS view      | full                

Implementation Details

• Metrics Collection: Reads from /proc/ filesystem for process/host metrics, combines with container metadata
• Cross-Level Correlation: Maps PIDs to container IDs, correlates network interfaces across isolation boundaries
• Minimal Impact: Surgical changes with comprehensive test coverage, no disruption to existing functionality
• Performance: Efficient metrics collection with benchmark tests for monitoring overhead

This implementation directly solves the monitoring visibility problem by providing comprehensive observability across all isolation levels while identifying and bridging the gaps between them.

Fixes the Docker monitoring problem referenced in: https://www.datadoghq.com/blog/the-docker-monitoring-problem/

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