isolation

type Backend interface {
	Mode() Mode

	// Requirements declares host requirements checked by preflight before
	// anything is mutated, and ordering dependencies on host-global units.
	Requirements() Requirements

	// Prepare materializes a node root for a slot: it unpacks or installs
	// artifacts and renders backend configuration.
	Prepare(ctx context.Context, n NodeSpec) (NodeRoot, error)

	Start(ctx context.Context, r SlotRef) error
	Stop(ctx context.Context, r SlotRef) error
	// Restart restarts the node stack only, never the host (soft reboot).
	Restart(ctx context.Context, r SlotRef) error
	// Destroy removes the node root and backend configuration for a slot.
	Destroy(ctx context.Context, r SlotRef) error

	Status(ctx context.Context, r SlotRef) (Status, error)

	// Exec runs a command in the node stack.
	Exec(ctx context.Context, r SlotRef, cmd ExecSpec) (ExecResult, error)
	// Logs streams logs for a unit in the node stack.
	Logs(ctx context.Context, r SlotRef, opts LogOptions) (io.ReadCloser, error)
}

type DirRoot struct {
	SlotName string
	Dir      string
}

type ExecResult struct {
	// Stdout is the captured standard output with trailing newlines trimmed.
	Stdout string
}

type ExecSpec struct {
	// Args is the command and its arguments.
	Args []string
}

type FakeBackend struct {
	FakeMode Mode
	// Dir is the directory the roots Prepare returns resolve under. It must be
	// an absolute directory other than the host root; see DirRoot.
	Dir string

	PrepareErr, StartErr, StopErr, RestartErr, DestroyErr, StatusErr, ExecErr error

	// FakeStatus is what Status reports when StatusErr is nil.
	FakeStatus Status

	// ExecFunc, when set, produces the result of Exec.
	ExecFunc func(ExecSpec) (ExecResult, error)
	// contains filtered or unexported fields
}

type Grant struct {
	Kind    GrantKind
	Purpose GrantPurpose
	// Source is the host path (or device node). It is empty for a GrantDevice
	// that only names a device class and has no node to expose.
	Source string
	// Target is the in-node path. Empty means the same as Source.
	Target   string
	ReadOnly bool
	// DeviceClass is a cgroup device class selector such as char-input, for a
	// GrantDevice that has no Source.
	DeviceClass string
	// DeviceAllow lists the device node paths or device group specifiers (for
	// example char-infiniband_verbs) a GrantMount of a device directory needs,
	// so nodes created in the directory after the node stack starts are usable.
	DeviceAllow []string `json:",omitempty"`
}

type GrantKind string

type GrantPurpose string

type LibDirMount struct {
	Index        int
	HostDir      string
	ContainerDir string
}

type LogOptions struct {
	// Unit is the systemd unit inside the node stack. Empty means all units.
	Unit string
	// Follow keeps the stream open for new entries.
	Follow bool
	// Lines limits output to the last N entries when positive.
	Lines int
}

type Mode string

type NodeRoot interface {
	SlotRef
	// Path maps an in-node absolute path to its path as seen by the agent.
	Path(inNode string) string
}

type NodeSpec struct {
	// Slot is the blue/green slot, for example kube1 or kube2.
	Slot string
	// Version is the Kubernetes version the node runs. It is informational:
	// no backend selects behavior from it.
	Version string
	// Grants are device, mount and library requests the node stack needs.
	Grants []Grant
}

type Requirements struct {
	// HostPackages are packages that must be present on the host.
	HostPackages []string
	// HostCommands are executables that must be resolvable on the host.
	HostCommands []string
	// WritablePaths are host paths that must be writable.
	WritablePaths []string
	// After lists host-global units the node stack must start after.
	After []string
}

type SlotName string

type SlotRef interface {
	Slot() string
}

type Status struct {
	// Running reports whether the node stack is up.
	Running bool
	// Detail is a human readable explanation.
	Detail string
}