To attach a virtual private gateway to your VPC

The following attach-vpn-gateway example attaches the specified virtual private gateway to the specified VPC.

aws ec2 attach-vpn-gateway \
    --vpn-gateway-id vgw-9a4cacf3 \
    --vpc-id vpc-a01106c2

Output:

{
    "VpcAttachment": {
        "State": "attaching",
        "VpcId": "vpc-a01106c2"
    }
}