Based on debian:jessie.
I use it on CoreOS for a site-to-site VPN connecting a local VLAN (on eth1) in the cloud to a remote on-premise network.
Examples can be found here: https://wiki.strongswan.org/projects/strongswan/wiki/IKEv2Examples
Example how to run:
docker run --name strongswan --name strongswan -d --privileged --net=host -v /etc/ipsec.d:/etc/ipsec.d mberner/strongswan:v2
Afterwards, you will also have to set up a route for your Docker containers to be able to reach the remote LAN by having the correct source IP addr (the one from eth1):
sudo iptables -t nat -I POSTROUTING -p all -s <Docker Subnet> -d <Remote Subnet> -j SNAT --to-source <Host Addr (eth1)>