$ cat ~/.local/share/lxc/stretch_default_1571630615861_44975/config
# Template used to create this container: /usr/share/rubygems-integration/all/gems/vagrant-lxc-1.4.3/scripts/lxc-template
# Parameters passed to the template: --tarball /home/boltronics/.vagrant.d/boxes/sitepoint-VAGRANTSLASH-debian-stretch-amd64/1.0.2/lxc/rootfs.tar.gz --config /home/boltronics/.vagrant.d/boxes/sitepoint-VAGRANTSLASH-debian-stretch-amd64/1.0.2/lxc/lxc-config
# Template script checksum (SHA-1): eae122a2d6cd572c26668257efa7963c2258186e
# For additional config options, please look at lxc.container.conf(5)

# Uncomment the following line to support nesting containers:
#lxc.include = /usr/share/lxc/config/nesting.conf
# (Be aware this has security implications)


##############################################
# Container specific configuration (automatically set)
lxc.include = /etc/lxc/default.conf
lxc.idmap = u 0 100000 65536
lxc.idmap = g 0 100000 65536
lxc.mount.auto = proc:mixed sys:ro cgroup:mixed
lxc.rootfs.path = dir:/home/boltronics/.local/share/lxc/stretch_default_1571630615861_44975/rootfs
lxc.uts.name = stretch_default_1571630615861_44975

##############################################
# Network configuration (automatically set)

##############################################
# vagrant-lxc base box specific configuration
# Default mount entries
lxc.mount.auto = cgroup:mixed proc:mixed sys:mixed
lxc.mount.entry = /sys/fs/fuse/connections sys/fs/fuse/connections none bind,optional 0 0

# Default console settings
lxc.tty.max = 4
lxc.pty.max = 1024

# Default capabilities
lxc.cap.drop = sys_module mac_admin mac_override sys_time sys_rawio

# When using LXC with apparmor, the container will be confined by default.
# If you wish for it to instead run unconfined, copy the following line
# (uncommented) to the container's configuration file.
#lxc.apparmor.profile = unconfined

# To support container nesting on an Ubuntu host while retaining most of
# apparmor's added security, use the following two lines instead.
#lxc.apparmor.profile = lxc-container-default-with-nesting
#lxc.hook.mount = /usr/share/lxc/hooks/mountcgroups

# If you wish to allow mounting block filesystems, then use the following
# line instead, and make sure to grant access to the block device and/or loop
# devices below in lxc.cgroup.devices.allow.
#lxc.apparmor.profile = lxc-container-default-with-mounting

##############################################
# vagrant-lxc container specific configuration
# VAGRANT-BEGIN
lxc.uts.name=stretch_default_1571630615861_44975
lxc.mount.entry=/sys/fs/pstore sys/fs/pstore none bind,optional 0 0
lxc.mount.entry=tmpfs tmp tmpfs nodev,nosuid,size=2G 0 0
lxc.mount.entry=/home/boltronics/Development/github.com/sitepoint/vmconfig/images/stretch vagrant none bind,create=dir 0 0
# VAGRANT-END
# VAGRANT-BEGIN
lxc.uts.name=stretch_default_1571630615861_44975
lxc.mount.entry=/sys/fs/pstore sys/fs/pstore none bind,optional 0 0
lxc.mount.entry=tmpfs tmp tmpfs nodev,nosuid,size=2G 0 0
lxc.mount.entry=/home/boltronics/Development/github.com/sitepoint/vmconfig/images/stretch vagrant none bind,create=dir 0 0
# VAGRANT-END
# VAGRANT-BEGIN
lxc.uts.name=stretch_default_1571630615861_44975
lxc.mount.entry=/sys/fs/pstore sys/fs/pstore none bind,optional 0 0
lxc.mount.entry=tmpfs tmp tmpfs nodev,nosuid,size=2G 0 0
lxc.mount.entry=/home/boltronics/Development/github.com/sitepoint/vmconfig/images/stretch vagrant none bind,create=dir 0 0
# VAGRANT-END

$ apt-cache policy vagrant vagrant-lxc | grep -B 1 -A 1 Installed
vagrant:
  Installed: 2.2.3+dfsg-1
  Candidate: 2.2.3+dfsg-1
--
vagrant-lxc:
  Installed: 1.4.3-1
  Candidate: 1.4.3-1
$ lxc-checkconfig 
Kernel configuration not found at /proc/config.gz; searching...
Kernel configuration found at /boot/config-4.19.0-6-amd64
--- Namespaces ---
Namespaces: enabled
Utsname namespace: enabled
Ipc namespace: enabled
Pid namespace: enabled
User namespace: enabled
Network namespace: enabled

--- Control groups ---
Cgroups: enabled

Cgroup v1 mount points: 
/sys/fs/cgroup/systemd
/sys/fs/cgroup/cpuset
/sys/fs/cgroup/pids
/sys/fs/cgroup/devices
/sys/fs/cgroup/cpu,cpuacct
/sys/fs/cgroup/perf_event
/sys/fs/cgroup/net_cls,net_prio
/sys/fs/cgroup/rdma
/sys/fs/cgroup/blkio
/sys/fs/cgroup/freezer
/sys/fs/cgroup/memory

Cgroup v2 mount points: 
/sys/fs/cgroup/unified

Cgroup v1 clone_children flag: enabled
Cgroup device: enabled
Cgroup sched: enabled
Cgroup cpu account: enabled
Cgroup memory controller: enabled
Cgroup cpuset: enabled

--- Misc ---
Veth pair device: enabled, loaded
Macvlan: enabled, not loaded
Vlan: enabled, loaded
Bridges: enabled, loaded
Advanced netfilter: enabled, loaded
CONFIG_NF_NAT_IPV4: enabled, loaded
CONFIG_NF_NAT_IPV6: enabled, not loaded
CONFIG_IP_NF_TARGET_MASQUERADE: enabled, not loaded
CONFIG_IP6_NF_TARGET_MASQUERADE: enabled, not loaded
CONFIG_NETFILTER_XT_TARGET_CHECKSUM: enabled, loaded
CONFIG_NETFILTER_XT_MATCH_COMMENT: enabled, not loaded
FUSE (for use with lxcfs): enabled, loaded

--- Checkpoint/Restore ---
checkpoint restore: enabled
CONFIG_FHANDLE: enabled
CONFIG_EVENTFD: enabled
CONFIG_EPOLL: enabled
CONFIG_UNIX_DIAG: enabled
CONFIG_INET_DIAG: enabled
CONFIG_PACKET_DIAG: enabled
CONFIG_NETLINK_DIAG: enabled
File capabilities: 

Note : Before booting a new kernel, you can check its configuration
usage : CONFIG=/path/to/config /usr/bin/lxc-checkconfig
$ cat ~/.config/lxc/default.conf 
lxc.include = /etc/lxc/default.conf

lxc.idmap = u 0 100000 65536
lxc.idmap = g 0 100000 65536
lxc.mount.auto = proc:mixed sys:ro cgroup:mixed
$ cat /etc/lxc/default.conf
#lxc.apparmor.profile = generated
lxc.apparmor.allow_nesting = 1
lxc.net.0.type = veth
lxc.net.0.flags = up
lxc.net.0.link = lxcbr0
$ cat Vagrantfile
VAGRANTFILE_API_VERSION = "2"

Vagrant.configure(VAGRANTFILE_API_VERSION) do |config|
  config.vm.box = "sitepoint/debian-stretch-amd64"
  config.vm.box_version = "1.0.2"
  config.vm.box_download_checksum_type = "sha256"
  config.vm.box_download_checksum = "c11b28024050ac94457e8b5e746365635a485e08d6c856cf7f2115363807b02d"

  config.vm.provider :lxc do |lxc|
    lxc.privileged = false
  end
end