engineclient

Documentation

Overview

Package engineclient defines the EngineClient interface between concrete container engine adaptor implementations and the engine-neutral watcher core.

Sub-packages implement specific container engines adaptors.

Index

• Constants
• func IsProcesslessContainer(err error) bool
• func NewProcesslessContainerError(nameorid string, typ string) error
• type ContainerEvent
• type ContainerEventType
• type EngineClient
• type ErrProcesslessContainer
  • func (err ErrProcesslessContainer) Error() string

Constants

const ProjectUnknown = "\000"

ProjectUnknown signals that the project name for a container event is unknown, as opposed to the zero project name.

Functions

func IsProcesslessContainer

func IsProcesslessContainer(err error) bool

IsProcesslessContainer returns true if the specified error is an ProcesslessContainerErr.

func NewProcesslessContainerError

func NewProcesslessContainerError(nameorid string, typ string) error

NewProcesslessContainerError returns a new ErrProcesslessContainer, stating the type of container and its name or ID.

Types

type ContainerEvent

type ContainerEvent struct {
	Type    ContainerEventType // type of lifecycle event.
	ID      string             // ID (or name) of container.
	Project string             // optional composer project name, or zero.
}

ContainerEvent is either a container lifecycle event of a container becoming alive, having died (more precise: its process exited), paused or unpaused.

type ContainerEventType

type ContainerEventType byte

ContainerEventType identifies and enumerates the (few) container lifecycle events we're interested in, regardless of a particular container engine.

const (
	ContainerStarted ContainerEventType = iota
	ContainerExited
	ContainerPaused
	ContainerUnpaused
)

Container lifecycle events, covering only "alive" containers.

type EngineClient

type EngineClient interface {
	// List all the currently alive and kicking containers. Return errors (only)
	// in case of (severe) conntection and daemon failures that aren't
	// transparent.
	List(ctx context.Context) ([]*whalewatcher.Container, error)
	// Query (only) the subset of container details of interest to us, given the
	// name or ID of a particular container.
	Inspect(ctx context.Context, nameorid string) (*whalewatcher.Container, error)
	// Stream container lifecycle events, limited to those events in the
	// lifecycle of containers getting born (=alive, as opposed to, say,
	// "conceived", dead/gone/"sleeping") and die.
	LifecycleEvents(ctx context.Context) (<-chan ContainerEvent, <-chan error)

	// (More or less) unique engine identifier; the exact format is
	// engine-specific.
	ID(ctx context.Context) string
	// Identifier of the type of container engine, such as "docker.com",
	// "containerd.io", et cetera.
	Type() string
	// Version information about the engine.
	Version(ctx context.Context) string
	// Container engine API path.
	API() string
	// Container engine PID, when known. Otherwise zero.
	PID() int

	// Underlying engine client (engine-specific).
	Client() interface{}

	// Clean up and release any engine client resources, if necessary.
	Close()
}

EngineClient defines the generic methods needed in order to watch the containers of a container engine, regardless of the specific type of engine.

type ErrProcesslessContainer

type ErrProcesslessContainer string

ErrProcesslessContainer is a custom error indicating that inspecting container details failed because it was a container without any process (yet or anymore), such as a container freshly created, and yet not started.

This usually happens due to transient changes between listing containers or processing lifecycle-related events and inspecting them, because there are no atomic operations available (and strictly necessary). There are already checks in place that usually avoid this error in static situations, but they can never give one hundred percent garantuees.

func (ErrProcesslessContainer) Error

func (err ErrProcesslessContainer) Error() string

Error returns the error message.