[Output Only] The status of the VPN tunnel, which can be one of the
following:
PROVISIONING: Resource is being allocated for the VPN tunnel.
WAITING_FOR_FULL_CONFIG: Waiting to receive all VPN-related
configs from the user. Network, TargetVpnGateway, VpnTunnel,
ForwardingRule, and Route resources are needed to setup the VPN
tunnel.
FIRST_HANDSHAKE: Successful first handshake with the peer VPN.
ESTABLISHED: Secure session is successfully established with the
peer VPN.
NETWORK_ERROR: Deprecated, replaced by NO_INCOMING_PACKETS
AUTHORIZATION_ERROR: Auth error (for example, bad shared secret).
NEGOTIATION_FAILURE: Handshake failed.
DEPROVISIONING: Resources are being deallocated for the VPN
tunnel.
FAILED: Tunnel creation has failed and the tunnel is not ready to
be used.
NO_INCOMING_PACKETS: No incoming packets from peer.
REJECTED: Tunnel configuration was rejected, can be result of
being denied access.
ALLOCATING_RESOURCES: Cloud VPN is in the process of allocating
all required resources.
STOPPED: Tunnel is stopped due to its Forwarding Rules being
deleted for Classic VPN tunnels or the project is in frozen
state.
PEER_IDENTITY_MISMATCH: Peer identity does not match peer IP,
probably behind NAT.
TS_NARROWING_NOT_ALLOWED: Traffic selector narrowing not allowed
for an HA-VPN tunnel.