vmconf

Documentation

Overview

Package vmconf defines an interface for converting particular CNI invocation results to networking configuration usable by a VM. It expects the CNI result to have the following properties:

• The results should contain an interface for a tap device, which will be used as the VM's tap device.
• The results should contain an interface with the same name as the tap device but with sandbox ID set to the containerID provided during CNI invocation. This should be a "pseudo-interface", not one that has actually been created. It represents the configuration that should be applied to the VM internally. The CNI "containerID" is, in this case, used more as a "vmID" to represent the VM's internal network interface.
• If the CNI results specify an IP associated with this interface, that IP should be used to statically configure the VM's internal network interface.

Index

• type StaticNetworkConf
  • func StaticNetworkConfFrom(result types.Result, containerID string) (*StaticNetworkConf, error)
  • func (c StaticNetworkConf) IPBootParam() string

Types

type StaticNetworkConf

type StaticNetworkConf struct {
	// TapName is the name of the tap device that the VM should use as its
	// network interface
	TapName string
	// NetNSPath is the path to the bind-mounted network namespace in which the VM's
	// tap device was created and thus where the VM should execute.
	NetNSPath string
	// VMIfName (optional) is interface name to configure. If left blank, config
	// is applied to the first (default) interface.
	VMIfName string

	// VMMacAddr is the mac address that callers should configure their VM to use internally.
	VMMacAddr string
	// VMMTU is the MTU that callers should configure their VM to use internally.
	VMMTU int
	// VMIPConfig is the ip configuration that callers should configure their VM's internal
	// primary interface to use.
	VMIPConfig *current.IPConfig
	// VMRoutes are the routes that callers should configure their VM's internal route table
	// to have
	VMRoutes []*types.Route

	// VMNameservers are the nameservers that callers should configure their VM to use internally
	VMNameservers []string
	// VMDomain is the resolver domain that callers should configure VM to use internally.
	VMDomain string
	// VMSearchDomans are the resolver search domains that callers should configure their VM to
	// use internally
	VMSearchDomains []string
	// VMResolverOptions are the resolve options that callers should configure their VM to use
	// internally
	VMResolverOptions []string
}

StaticNetworkConf holds the configuration needed to configure a VM's networking stack. It is generally parsed from a CNI result object via the StaticNetworkConfFrom function.

Fields beginning with "VM" are references to entities that need to be setup to exist *within* the VM once the VM is started.

func StaticNetworkConfFrom

func StaticNetworkConfFrom(result types.Result, containerID string) (*StaticNetworkConf, error)

StaticNetworkConfFrom takes the result of a CNI invocation that conforms to the specification in this package's docstring and converts it to a StaticNetworkConf object that the caller can use to configure their VM with.

func (StaticNetworkConf) IPBootParam

func (c StaticNetworkConf) IPBootParam() string

IPBootParam provides a string that can be used as the argument to "ip=" in a Linux kernel boot parameters in order to boot a machine with network settings matching those in a StaticNetworkConf object.

See "ip=" section of kernel docs here for more details: https://www.kernel.org/doc/Documentation/filesystems/nfs/nfsroot.txt

Due to the limitation of "ip=", not all configuration specified in StaticNetworkConf can be applied automatically. In particular:

• The MacAddr and MTU cannot be applied
• The only routes created will match what's specified in VMIPConfig; VMRoutes will be ignored.
• Only up to two namesevers can be supplied. If VMNameservers is has more than 2 entries, only the first two in the slice will be applied in the VM.
• VMDomain, VMSearchDomains and VMResolverOptions will be ignored
• Nameserver settings are also only set in /proc/net/pnp. Most applications will thus require /etc/resolv.conf to be a symlink to /proc/net/pnp in order to resolve names as expected.