Ubuntu 18 LTS default container image, i.e. ubuntu:18.04.
strongswan 5.6.2-1ubuntu2.4.
$ ipsec --version
Linux strongSwan U5.6.2/K4.15.0-38-generic
Most ipsec commands like
ipsec status
ipsec statusall
ipsec listalgs
do not return any output.
This seems to happen only in LXD containers running Ubuntu 18 LTS and is reproducible in new unconfigured containers running the same Linux distribution.
The problem does not happen, for example, in KVM virtual machine running Ubuntu 18 LTS and same version of strongswan.