Hello I wanted to do some advertising 
I adapted a lxd exporter to work with the newest lxd version (container+vms)
I use this one with us on the approx. 20 container/vms run.
i have built a docker image for it, if desired i can also provide the binary.
Do you have any ideas which metrics are still interesting?
current output:
# HELP lxd_instance_cpu_usage instanceCPU Usage in Seconds
# TYPE lxd_instance_cpu_usage gauge
lxd_instance_cpu_usage{instance_name="c1",instance_type="container"} 1.814131565e+10
lxd_instance_cpu_usage{instance_name="v1",instance_type="virtual-machine"} 6.695872399e+09
# HELP lxd_instance_mem_usage instanceMemory Usage
# TYPE lxd_instance_mem_usage gauge
lxd_instance_mem_usage{instance_name="c1",instance_type="container"} 3.48270592e+08
lxd_instance_mem_usage{instance_name="v1",instance_type="virtual-machine"} 2.99933696e+08
# HELP lxd_instance_mem_usage_peak instanceMemory Usage Peak
# TYPE lxd_instance_mem_usage_peak gauge
lxd_instance_mem_usage_peak{instance_name="c1",instance_type="container"} 5.81820416e+08
lxd_instance_mem_usage_peak{instance_name="v1",instance_type="virtual-machine"} 2.9556736e+08
# HELP lxd_instance_network_usage instanceNetwork Usage
# TYPE lxd_instance_network_usage gauge
lxd_instance_network_usage{instance_name="c1",instance_type="container",interface="eth0",operation="BytesReceived"} 767411
lxd_instance_network_usage{instance_name="c1",instance_type="container",interface="eth0",operation="BytesSent"} 22734
lxd_instance_network_usage{instance_name="c1",instance_type="container",interface="eth0",operation="PacketsReceived"} 418
lxd_instance_network_usage{instance_name="c1",instance_type="container",interface="eth0",operation="PacketsSent"} 231
lxd_instance_network_usage{instance_name="c1",instance_type="container",interface="lo",operation="BytesReceived"} 1848
lxd_instance_network_usage{instance_name="c1",instance_type="container",interface="lo",operation="BytesSent"} 1848
lxd_instance_network_usage{instance_name="c1",instance_type="container",interface="lo",operation="PacketsReceived"} 20
lxd_instance_network_usage{instance_name="c1",instance_type="container",interface="lo",operation="PacketsSent"} 20
lxd_instance_network_usage{instance_name="v1",instance_type="virtual-machine",interface="enp5s0",operation="BytesReceived"} 4237
lxd_instance_network_usage{instance_name="v1",instance_type="virtual-machine",interface="enp5s0",operation="BytesSent"} 4635
lxd_instance_network_usage{instance_name="v1",instance_type="virtual-machine",interface="enp5s0",operation="PacketsReceived"} 48
lxd_instance_network_usage{instance_name="v1",instance_type="virtual-machine",interface="enp5s0",operation="PacketsSent"} 53
# HELP lxd_instance_pid instancePID
# TYPE lxd_instance_pid gauge
lxd_instance_pid{instance_name="c1",instance_type="container"} 2.63507e+06
lxd_instance_pid{instance_name="v1",instance_type="virtual-machine"} 2.639881e+06
# HELP lxd_instance_process_count instancenumber of process Running
# TYPE lxd_instance_process_count gauge
lxd_instance_process_count{instance_name="c1",instance_type="container"} 51
lxd_instance_process_count{instance_name="v1",instance_type="virtual-machine"} 20
# HELP lxd_instance_running_status instanceRunning Status
# TYPE lxd_instance_running_status gauge
lxd_instance_running_status{instance_name="c1",instance_type="container"} 1
lxd_instance_running_status{instance_name="v1",instance_type="virtual-machine"} 1
# HELP lxd_instance_swap_usage instanceSwap Usage
# TYPE lxd_instance_swap_usage gauge
lxd_instance_swap_usage{instance_name="c1",instance_type="container"} 0
lxd_instance_swap_usage{instance_name="v1",instance_type="virtual-machine"} 0
# HELP lxd_instance_swap_usage_peak instanceSwap Usage Peak
# TYPE lxd_instance_swap_usage_peak gauge
lxd_instance_swap_usage_peak{instance_name="c1",instance_type="container"} 0
lxd_instance_swap_usage_peak{instance_name="v1",instance_type="virtual-machine"} 0