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Flintlock

Understanding common flintlockd errors.

If you create a MicroVM but find that the firecracker.stdout or stderr or log files for it are empty, it means that flintlockd was not able to start the MicroVM at all.

Flintlock logs can be watched by running:

journalctl -fu flintlockd.service

Snapshotter not loaded​

"failed to reconcile vmid FOO/BAR/ID: executing plan: executing plan steps: executing steps: executing step runtime_volume_mount: mount images docker.io/claudiaberesford/capmvm-kubernetes-arm:1.21.8 for volume use: checking if image docker.io/claudiaberesford/capmvm-kubernetes-arm:1.21.8 has been unpacked with snapshotter devmapper: snapshotter not loaded: devmapper: invalid argument"

Your containerd storage is not provisioned.

You can check this with dmsetup ls. It should return at least one line:

flintlock-dev-thinpool  (253:0)

The loop-backed thinpool will not survive restarts, so you'll need to recreate this whenever you reboot.

To remedy:

  • Recreate the thinpool: sudo ./provision.sh devpool
  • Restart containerd: systemctl restart containerd-dev.service
  • Restart flintlock: systemctl restart flintlockd.service

Operation not supported (network, macvtap)​

I wish I had grabbed the error when I saw it, but alas I did not have the foresight that I would be writing this page.

It was something along the lines of:

"failed to reconcile vmid <FOO/BAR/ID>: executing plan: executing plan steps: executing steps: executing step network_iface_create: creating network interface: Operation not supported"
# or
"failed to reconcile vmid <FOO/BAR/ID>: executing plan: executing plan steps: executing steps: executing step network_iface_create: creating network interface: Operation not permitted"

This means that your device does not have the module to create macvtap or macvlan devices.

You may also see:

RTNETLINK answers: Operation not supported

if you try to create a device yourself.

To remedy, follow the instructions in the build guide to install the extra kernel modules.

A parent network device name is required for attaching a TAP interface​

"failed to reconcile vmid <FOO/BAR/ID>: executing plan: executing plan steps: executing steps: executing step network_iface_create: creating network interface: a parent network device name is required for attaching a TAP interface"

This means that you are trying to create a MicroVM in "bridge mode", ie: you have set the eth1 interface type to 1 in a flintlock spec or have set spec.template.spec.networkInterfaces[0].type to tap, but have not set a bridge-name in either the spec or the flintlockd config.

Option A: Set the MicroVM to be created with macvtap instead, by setting the eth1 interface type to 0 (if just using flintlock), or by setting spec.template.spec.networkInterfaces[0].type to macvtap.

Option B: Open /etc/opt/flintlockd/config.yaml and set bridge-name to the name of a bridge you have created. Save the file and restart the service: systemctl restart flintlockd.service. This bridge will be used as a parent for all MicroVM tap devices.

Option C: Edit the flintlock or capmvm spec to use a specific bridge for that MicroVM.

// flintlock spec
...
"interfaces": [
    {
        "device_id": "eth1",
        "type": 1,
        "overrides": {
            "bridge_name": "foo"
        }
    }
],
...
# capmvm spec
...
networkInterfaces:
- guestDeviceName: eth1
  type: tap
    overrides:
        bridgeName: foobar
...

A parent network device name is required for macvtap interfaces​

"failed to reconcile vmid FOO/BAR/ID: executing plan: executing plan steps: executing steps: executing step network_iface_create: creating network interface: a parent network device name is required for macvtap interfaces"

This means that you are trying to create a MicroVM in "macvtap mode", ie: you have set the eth1 interface type to 0 in a flintlock spec or have set spec.template.spec.networkInterfaces[0].type to macvtap, but have not set a parent-iface in the flintlockd config.

Option A: Set the MicroVM to be created with tap (bridge mode) instead, by setting the eth1 interface type to 1 (if just using flintlock), or by setting spec.template.spec.networkInterfaces[0].type to tap. Requires creating a bridge and configuring it in /etc/opt/flintlockd/config.yaml under bridge-name.

Option B: Open /etc/opt/flintlockd/config.yaml and set parent-iface to the name of your device's default wired interface (eg eth0). Save the file and restart the service: systemctl restart flintlockd.service. This interface will be used as a parent for all MicroVM macvtap devices.