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The containerd client is very chatty at the best of times. Because the libcontained API is stateless and references containers and processes by string ID for every method call, the implementation is essentially forced to use the containerd client in a way which amplifies the number of redundant RPCs invoked to perform any operation. The libcontainerd remote implementation has to reload the containerd container, task and/or process metadata for nearly every operation. This in turn amplifies the number of context switches between dockerd and containerd to perform any container operation or handle a containerd event, increasing the load on the system which could otherwise be allocated to workloads. Overhaul the libcontainerd interface to reduce the impedance mismatch with the containerd client so that the containerd client can be used more efficiently. Split the API out into container, task and process interfaces which the consumer is expected to retain so that libcontainerd can retain state---especially the analogous containerd client objects---without having to manage any state-store inside the libcontainerd client. Signed-off-by: Cory Snider <csnider@mirantis.com>
104 lines
3.9 KiB
Go
104 lines
3.9 KiB
Go
package types // import "github.com/docker/docker/libcontainerd/types"
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import (
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"context"
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"syscall"
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"time"
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"github.com/containerd/containerd"
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"github.com/containerd/containerd/cio"
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specs "github.com/opencontainers/runtime-spec/specs-go"
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)
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// EventType represents a possible event from libcontainerd
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type EventType string
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// Event constants used when reporting events
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const (
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EventUnknown EventType = "unknown"
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EventExit EventType = "exit"
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EventOOM EventType = "oom"
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EventCreate EventType = "create"
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EventStart EventType = "start"
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EventExecAdded EventType = "exec-added"
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EventExecStarted EventType = "exec-started"
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EventPaused EventType = "paused"
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EventResumed EventType = "resumed"
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)
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// EventInfo contains the event info
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type EventInfo struct {
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ContainerID string
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ProcessID string
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Pid uint32
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ExitCode uint32
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ExitedAt time.Time
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Error error
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}
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// Backend defines callbacks that the client of the library needs to implement.
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type Backend interface {
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ProcessEvent(containerID string, event EventType, ei EventInfo) error
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}
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// Process of a container
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type Process interface {
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// Pid is the system specific process id
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Pid() uint32
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// Kill sends the provided signal to the process
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Kill(ctx context.Context, signal syscall.Signal) error
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// Resize changes the width and height of the process's terminal
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Resize(ctx context.Context, width, height uint32) error
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// Delete removes the process and any resources allocated returning the exit status
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Delete(context.Context) (*containerd.ExitStatus, error)
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}
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// Client provides access to containerd features.
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type Client interface {
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Version(ctx context.Context) (containerd.Version, error)
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// LoadContainer loads the metadata for a container from containerd.
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LoadContainer(ctx context.Context, containerID string) (Container, error)
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// NewContainer creates a new containerd container.
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NewContainer(ctx context.Context, containerID string, spec *specs.Spec, shim string, runtimeOptions interface{}, opts ...containerd.NewContainerOpts) (Container, error)
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}
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// Container provides access to a containerd container.
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type Container interface {
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Start(ctx context.Context, checkpointDir string, withStdin bool, attachStdio StdioCallback) (Task, error)
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Task(ctx context.Context) (Task, error)
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// AttachTask returns the current task for the container and reattaches
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// to the IO for the running task. If no task exists for the container
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// a NotFound error is returned.
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//
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// Clients must make sure that only one reader is attached to the task.
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AttachTask(ctx context.Context, attachStdio StdioCallback) (Task, error)
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// Delete removes the container and associated resources
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Delete(context.Context) error
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}
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// Task provides access to a running containerd container.
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type Task interface {
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Process
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// Pause suspends the execution of the task
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Pause(context.Context) error
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// Resume the execution of the task
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Resume(context.Context) error
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Stats(ctx context.Context) (*Stats, error)
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// Pids returns a list of system specific process ids inside the task
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Pids(context.Context) ([]containerd.ProcessInfo, error)
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Summary(ctx context.Context) ([]Summary, error)
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// ForceDelete forcefully kills the task's processes and deletes the task
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ForceDelete(context.Context) error
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// Status returns the executing status of the task
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Status(ctx context.Context) (containerd.Status, error)
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// Exec creates and starts a new process inside the task
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Exec(ctx context.Context, processID string, spec *specs.Process, withStdin bool, attachStdio StdioCallback) (Process, error)
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UpdateResources(ctx context.Context, resources *Resources) error
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CreateCheckpoint(ctx context.Context, checkpointDir string, exit bool) error
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}
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// StdioCallback is called to connect a container or process stdio.
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type StdioCallback func(io *cio.DirectIO) (cio.IO, error)
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// InitProcessName is the name given to the first process of a container
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const InitProcessName = "init"
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