ECS/VPC Public Network Connectivity Troubleshooting

Automated diagnosis of public network connectivity for Alibaba Cloud ECS instances and VPC cloud services. Two core capabilities only:

ECS public network diagnosis — full-chain check for an ECS instance covering public IP reachability and security-group blocking; the NAT-gateway egress path for instances without a public IP is handled automatically as a sub-path (the script picks Branch A / Branch B by itself).
VPC cloud service public network diagnosis — public egress check for a cloud service (DataWorks / SAE / ACK, etc.) behind a VSwitch (NAT gateway / SNAT / route / EIP).

Execution Principle (script-only, no fallback)

All diagnostic operations MUST be performed by invoking the bundled Python scripts under scripts/. There are exactly three:

Allowed invocation	Purpose
`python3 scripts/sts_create.py`	Obtain/validate credentials (runs first)
`python3 scripts/ecs_public_troubleshoot.py`	ECS public network diagnosis
`python3 scripts/vpc_service_public_troubleshoot.py`	VPC cloud service diagnosis