libkrun virtio-net driver enables TSO offloading and checksum
offloading by default, so we must use vment-helper --enable-tso and
--enable-checksum-offload with krunkit. These options do not work with
vfkit.
* vmnet: Improve --network vmnet-shared validation
Previously we did not check that the helper can run with the
--close-from=4 option, so the command could succeed when incorrect
sudoers configuration. For example a user with liberal NOPASSWD rule,
but without the closefrom_override option.
When the check failed, we log unhelpful log:
libmachine: Failed to run vmnet-helper:
%!w(*exec.ExitError=&{0x14000135e30 [115 117 100 111 58 32 97 ... 101 100 10]})
And we returned a bool, so the caller could not provide a suggestion how
to resolve the issue.
Fix by:
- Rename vment.HelperAvaialble to vment.ValidateHelper
- Return an error describing the issue, including a reason.Kind that can
be used to provide a suggestion for resolving the issue.
- Include the ExitError.Stderr int the error. This includes helpful
error messages from sudo.
- Add new reason.NotConfiguredVmnetHelper error
- Improve log when vment.ValidateHelper() succeeded
Example error flow - vment-helper not installed:
% minikube start --driver vfkit --network vmnet-shared
😄 minikube v1.35.0 on Darwin 15.4.1 (arm64)
✨ Using the vfkit (experimental) driver based on user configuration
🙈 Exiting due to NOT_FOUND_VMNET_HELPER: failed to validate vmnet-shared network:
stat /opt/vmnet-helper/bin/vmnet-helper: no such file or directory
💡 Suggestion:
vmnet-helper was not found on the system, resolve by:
Option 1) Installing vmnet-helper:
https://github.com/nirs/vmnet-helper#installation
Option 2) Using the nat network:
minikube start<no value> --driver vfkit --network nat
I resolved the issue by installing vmnet-helper but I did not configured
the sudoers rule:
% minikube start --driver vfkit --network vmnet-shared
😄 minikube v1.35.0 on Darwin 15.4.1 (arm64)
✨ Using the vfkit (experimental) driver based on user configuration
🙈 Exiting due to NOT_CONFIGURED_VMNET_HELPER: failed to validate vmnet-shared network:
exit status 1: sudo: you are not permitted to use the -C option
💡 Suggestion:
Configure vmnet-helper to run without a password.
Please install a vmnet-helper sudoers rule using these instructions:
https://github.com/nirs/vmnet-helper#granting-permission-to-run-vmnet-helper
After installing the sudoers rule minikube could start.
* vfkit: Use helper --socket instead of --fd
The --fd option avoids the need to manage a bound unix sockets, in
particular the limit on unix socket length. It is also more secure;
only the process inheriting the socket can access the helper. However it
requires the sudo --close-from= option, which may not work for some
users. We don't understand why it does not work, and debugging it is
hard since users are not happy to share their local sudoers
configuration.
Avoid the trouble by switching to the --socket option. In this case we
pass a unix socket path to the helper and vfkit. The helper creates a
bound unix datagram socket in the specified path, and waits until vfkit
connects to the socket. When vfkit connects to the unix socket the
programs are connected in the same way they are connected by passing
file descriptors.
When running minikube we will see 3 new files in the machine directory:
- `vfkit-fb64-7802.sock`: vfkit unix datagram socket
- `vmnet-helper.sock`: vmnet-helper unix datagram socket
- `vmnet-helper.sock.lock`: lockfile for vment-helper socket
The files are deleted when vmnet-helper and vfkit are terminated
gracefully. If they are killed the stale files are replaced on the next
start.
Issues:
- If the path exceeds the limit (104 characters), opening the socket
will fail. We have the sames issue with vfkit management socket.
* vment: Fallback to interactive sudo
If vmnet-helper sudoers rule is not configured or does not work for the
user, maybe because the user has disabled the NOPASSWD option, we used
to fail, recommending to configure vmnet sudoers rule. This does not
help a user that cannot fix the sudoers configuration.
Since we switched to --socket mode, we can work without a sudoers rule.
If we can interact with the user, we fall back to interactive sudo. The
user can enter a password to start the machine.
Example run with --interactive=false:
% minikube start --driver vfkit --network vmnet-shared --interactive=false
😄 minikube v1.35.0 on Darwin 15.4.1 (arm64)
✨ Using the vfkit (experimental) driver based on user configuration
🙈 Exiting due to NOT_CONFIGURED_VMNET_HELPER: failed to validate vmnet-shared network:
exit status 1: sudo: a password is required
💡 Suggestion:
Configure vmnet-helper to run without a password.
Please install a vmnet-helper sudoers rule using these instructions:
https://github.com/nirs/vmnet-helper#granting-permission-to-run-vmnet-helper
Example run with --interactive (default):
% minikube start --driver vfkit --network vmnet-shared
😄 minikube v1.35.0 on Darwin 15.4.1 (arm64)
✨ Using the vfkit (experimental) driver based on user configuration
💡 Unable to run vmnet-helper without a password
To configure vment-helper to run without a password, please check the documentation:
https://github.com/nirs/vmnet-helper/#granting-permission-to-run-vmnet-helper
Password:
👍 Starting "minikube" primary control-plane node in "minikube" cluster
🔥 Creating vfkit VM (CPUs=2, Memory=6000MB, Disk=20000MB) ...
🐳 Preparing Kubernetes v1.33.0 on Docker 27.4.0 ...
▪ Generating certificates and keys ...
▪ Booting up control plane ...
▪ Configuring RBAC rules ...
🔗 Configuring bridge CNI (Container Networking Interface) ...
🔎 Verifying Kubernetes components...
▪ Using image gcr.io/k8s-minikube/storage-provisioner:v5
🌟 Enabled addons: storage-provisioner, default-storageclass
🏄 Done! kubectl is now configured to use "minikube" cluster and "default" namespace by default
* vfkit: Remove temporary variable
Remove temporary and unneeded mac variable. It is easier to follow the
code when we use d.MACAddress.
* vfkit: Promote state change to INFO level
System state changes should be more visible to make debugging easier.
* vmnet: Add vmnet package
The package manages the vmnet-helper[1] child process, providing
connection to the vmnet network without running the guest as root.
We will use vmnet-helper for the vfkit driver, which does not have a way
to use shared network, when guests can access other guest in the
network. We can use it later with the qemu driver as alternative to
socket_vmnet.
[1] https://github.com/nirs/vmnet-helper
* vfkit: add vmnet-shared network
Add new network option for vfkit "vmnet-shared", connecting vfkit to the
vmnet shared network. Clusters using this network can access other
clusters in the same network, similar to socket_vmnet with QEMU driver.
If network is not specified, we default to the "nat" network, keeping
the previous behavior. If network is "vmnet-shared", the vfkit driver
manages 2 processes: vfkit and vmnet-helper.
Like vfkit, vmnet-helper is started in the background, in a new process
group, so it not terminated if the minikube process group is terminate.
Since vmnet-helper requires root to start the vmnet interface, we start
it with sudo, creating 2 child processes. vmnet-helper drops privileges
immediately after starting the vmnet interface, and run as the user and
group running minikube.
Stopping the cluster will stop sudo, which will stop the vmnet-helper
process. Deleting the cluster kill both sudo and vmnet-helper by killing
the process group.
This change is not complete, but it is good enough to play with the new
shared network.
Example usage:
1. Install vmnet-helper:
https://github.com/nirs/vmnet-helper?tab=readme-ov-file#installation
2. Setup vmnet-helper sudoers rule:
https://github.com/nirs/vmnet-helper?tab=readme-ov-file#granting-permission-to-run-vmnet-helper
3. Start 2 clusters with vmnet-shared network:
% minikube start -p c1 --driver vfkit --network vmnet-shared
...
% minikube start -p c2 --driver vfkit --network vmnet-shared
...
% minikube ip -p c1
192.168.105.18
% minikube ip -p c2
192.168.105.19
4. Both cluster can access the other cluster:
% minikube -p c1 ssh -- ping -c 3 192.168.105.19
PING 192.168.105.19 (192.168.105.19): 56 data bytes
64 bytes from 192.168.105.19: seq=0 ttl=64 time=0.621 ms
64 bytes from 192.168.105.19: seq=1 ttl=64 time=0.989 ms
64 bytes from 192.168.105.19: seq=2 ttl=64 time=0.490 ms
--- 192.168.105.19 ping statistics ---
3 packets transmitted, 3 packets received, 0% packet loss
round-trip min/avg/max = 0.490/0.700/0.989 ms
% minikube -p c2 ssh -- ping -c 3 192.168.105.18
PING 192.168.105.18 (192.168.105.18): 56 data bytes
64 bytes from 192.168.105.18: seq=0 ttl=64 time=0.289 ms
64 bytes from 192.168.105.18: seq=1 ttl=64 time=0.798 ms
64 bytes from 192.168.105.18: seq=2 ttl=64 time=0.993 ms
--- 192.168.105.18 ping statistics ---
3 packets transmitted, 3 packets received, 0% packet loss
round-trip min/avg/max = 0.289/0.693/0.993 ms
* reason: Remove trailing whitepsace
Trailing whitespace is removed by some editors or displayed as a
warning. Clean up to make it easy to make maintain this file.
* start: Validate vfkit --network option
The vfkit driver supports now `nat` and `vmnet-shared` network options.
The `nat` option provides the best performance and is always available,
so it is the default network option. The `vmnet-shared` option provides
access between machines with lower performance compared to `nat`.
If `vment-shared` option is selected, we verify that vmnet-helper is
available. The check ensure that vmnet-helper is installed and sudoers
configuration allows the current user to run vment-helper without a
password.
If validating vment-helper failed, we return a new NotFoundVmnetHelper
reason pointing to vment-helper installation docs or recommending to use
`nat`. This is based on how we treat missing socket_vmnet for QEMU
driver.
* site: Document vfkit network options
Nir Soffer