I added the device like so,
lxc config device add zmvm webcam0 unix-char mode=0777 path=/dev/webcam0 required=false
but on starting the container i get,
$ lxc start zmvm
Error: not a directory
Try `lxc info --show-log zmvm` for more info
Log shows
$ lxc info --show-log zmvm |tail -30
lxc 20180701132951.748 TRACE lxc_commands - commands.c:lxc_cmd:311 - Connection refused - Command "get_state" failed to connect command socket
lxc 20180701132951.759 INFO lxc_confile - confile.c:set_config_idmaps:1653 - Read uid map: type u nsid 0 hostid 1000000 range 65536
lxc 20180701132951.759 INFO lxc_confile - confile.c:set_config_idmaps:1653 - Read uid map: type g nsid 0 hostid 1000000 range 65536
lxc 20180701132951.761 TRACE lxc_commands - commands.c:lxc_cmd:311 - Connection refused - Command "get_cgroup" failed to connect command socket
lxc 20180701132951.761 TRACE lxc_commands - commands.c:lxc_cmd:311 - Connection refused - Command "get_state" failed to connect command socket
lxc 20180701133035.861 TRACE lxc_commands - commands.c:lxc_cmd:311 - Connection refused - Command "get_cgroup" failed to connect command socket
lxc 20180701133035.861 TRACE lxc_commands - commands.c:lxc_cmd:311 - Connection refused - Command "get_state" failed to connect command socket
lxc 20180701133035.870 INFO lxc_confile - confile.c:set_config_idmaps:1653 - Read uid map: type u nsid 0 hostid 1000000 range 65536
lxc 20180701133035.870 INFO lxc_confile - confile.c:set_config_idmaps:1653 - Read uid map: type g nsid 0 hostid 1000000 range 65536
lxc 20180701133035.871 TRACE lxc_commands - commands.c:lxc_cmd:311 - Connection refused - Command "get_cgroup" failed to connect command socket
lxc 20180701133035.871 TRACE lxc_commands - commands.c:lxc_cmd:311 - Connection refused - Command "get_state" failed to connect command socket
lxc 20180701133051.547 TRACE lxc_commands - commands.c:lxc_cmd:311 - Connection refused - Command "get_cgroup" failed to connect command socket
lxc 20180701133051.547 TRACE lxc_commands - commands.c:lxc_cmd:311 - Connection refused - Command "get_state" failed to connect command socket
lxc 20180701133051.556 TRACE lxc_commands - commands.c:lxc_cmd:311 - Connection refused - Command "get_cgroup" failed to connect command socket
lxc 20180701133051.556 TRACE lxc_commands - commands.c:lxc_cmd:311 - Connection refused - Command "get_state" failed to connect command socket
lxc 20180701133051.556 TRACE lxc_commands - commands.c:lxc_cmd:311 - Connection refused - Command "get_cgroup" failed to connect command socket
lxc 20180701133051.556 TRACE lxc_commands - commands.c:lxc_cmd:311 - Connection refused - Command "get_state" failed to connect command socket
lxc 20180701133127.213 TRACE lxc_commands - commands.c:lxc_cmd:311 - Connection refused - Command "get_cgroup" failed to connect command socket
lxc 20180701133127.213 TRACE lxc_commands - commands.c:lxc_cmd:311 - Connection refused - Command "get_state" failed to connect command socket
lxc 20180701133127.218 TRACE lxc_commands - commands.c:lxc_cmd:311 - Connection refused - Command "get_cgroup" failed to connect command socket
lxc 20180701133127.218 TRACE lxc_commands - commands.c:lxc_cmd:311 - Connection refused - Command "get_state" failed to connect command socket
lxc 20180701133127.218 TRACE lxc_commands - commands.c:lxc_cmd:311 - Connection refused - Command "get_cgroup" failed to connect command socket
lxc 20180701133127.218 TRACE lxc_commands - commands.c:lxc_cmd:311 - Connection refused - Command "get_state" failed to connect command socket
lxc 20180701133132.120 TRACE lxc_commands - commands.c:lxc_cmd:311 - Connection refused - Command "get_cgroup" failed to connect command socket
lxc 20180701133132.120 TRACE lxc_commands - commands.c:lxc_cmd:311 - Connection refused - Command "get_state" failed to connect command socket
lxc 20180701133132.125 TRACE lxc_commands - commands.c:lxc_cmd:311 - Connection refused - Command "get_cgroup" failed to connect command socket
lxc 20180701133132.125 TRACE lxc_commands - commands.c:lxc_cmd:311 - Connection refused - Command "get_state" failed to connect command socket
lxc 20180701133132.125 TRACE lxc_commands - commands.c:lxc_cmd:311 - Connection refused - Command "get_cgroup" failed to connect command socket
lxc 20180701133132.125 TRACE lxc_commands - commands.c:lxc_cmd:311 - Connection refused - Command "get_state" failed to connect command socket