containerd

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 Go to latest Published: Jul 19, 2017 License: Apache-2.0, CC-BY-SA-4.0 Imports: 57 Imported by: 0

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containerd is an industry-standard container runtime with an emphasis on simplicity, robustness and portability. It is available as a daemon for Linux and Windows, which can manage the complete container lifecycle of its host system: image transfer and storage, container execution and supervision, low-level storage and network attachments, etc.

containerd is designed to be embedded into a larger system, rather than being used directly by developers or end-users.

Features

Client

containerd offers a full client package to help you integrate containerd into your platform.


import "github.com/containerd/containerd"

func main() {
	client, err := containerd.New("/run/containerd/containerd.sock")
	defer client.Close()
}

Namespaces

Namespaces allow multiple consumers to use the same containerd without conflicting with each other. It has the benefit of sharing content but still having separation with containers and images.

To set a namespace for requests to the API:

context    = context.Background()
// create a context for docker
docker = namespaces.WithNamespace(context, "docker")

containerd, err := client.NewContainer(docker, "id")

To set a default namespace on the client:

client, err := containerd.New(address, containerd.WithDefaultNamespace("docker"))

Distribution

// pull an image
image, err := client.Pull(context, "docker.io/library/redis:latest")

// push an image
err := client.Push(context, "docker.io/library/redis:latest", image.Target())

OCI Runtime Specification

containerd fully supports the OCI runtime specification for running containers. We have built in functions to help you generate runtime specifications based on images as well as custom parameters.

spec, err := containerd.GenerateSpec(containerd.WithImageConfig(context, image))

Containers

In containerd, a container is a metadata object. Resources such as an OCI runtime specification, image, root filesystem, and other metadata can be attached to a container.

redis, err := client.NewContainer(context, "redis-master",
	containerd.WithSpec(spec),
)
defer redis.Delete(context)

Root Filesystems

containerd allows you to use overlay or snapshot filesystems with your containers. It comes with builtin support for overlayfs and btrfs.

// pull an image and unpack it into the configured snapshotter
image, err := client.Pull(context, "docker.io/library/redis:latest", containerd.WithPullUnpack)

// allocate a new RW root filesystem for a container based on the image
redis, err := client.NewContainer(context, "redis-master",
	containerd.WithSpec(spec),
	containerd.WithNewRootFS("redis-rootfs", image),
)

// use a readonly filesystem with multiple containers
for i := 0; i < 10; i++ {
	id := fmt.Sprintf("id-%s", i)
	container, err := client.NewContainer(ctx, id,
		containerd.WithSpec(spec),
		containerd.WithNewReadonlyRootFS(id, image),
	)
}

Tasks

Taking a container object and turning it into a runnable process on a system is done by creating a new Task from the container. A task represents the runnable object within containerd.

// create a new task
task, err := redis.NewTask(context, containerd.Stdio)
defer task.Delete(context)

// the task is now running and has a pid that can be use to setup networking
// or other runtime settings outside of containerd
pid := task.Pid()

// start the redis-server process inside the container
err := task.Start(context)

// wait for the task to exit and get the exit status
status, err := task.Wait(context)

Checkpoint and Restore

If you have criu installed on your machine you can checkpoint and restore containers and their tasks. This allow you to clone and/or live migrate containers to other machines.

// checkpoint the task then push it to a registry
checkpoint, err := task.Checkpoint(context, containerd.WithExit)

err := client.Push(context, "myregistry/checkpoints/redis:master", checkpoint)

// on a new machine pull the checkpoint and restore the redis container
image, err := client.Pull(context, "myregistry/checkpoints/redis:master")

checkpoint := image.Target()

redis, err = client.NewContainer(context, "redis-master", containerd.WithCheckpoint(checkpoint, "redis-rootfs"))
defer container.Delete(context)

task, err = redis.NewTask(context, containerd.Stdio, containerd.WithTaskCheckpoint(checkpoint))
defer task.Delete(context)

err := task.Start(context)

Developer Quick-Start

To build the daemon and ctr simple test client, the following build system dependencies are required:

  • Go 1.8.x or above (requires 1.8 due to use of golang plugin(s))
  • Protoc 3.x compiler and headers (download at the Google protobuf releases page)
  • Btrfs headers and libraries for your distribution. Note that building the btrfs driver can be disabled via build tag removing this dependency.

For proper results, install the protoc release into /usr/local on your build system. For example, the following commands will download and install the 3.1.0 release for a 64-bit Linux host:

$ wget -c https://github.com/google/protobuf/releases/download/v3.1.0/protoc-3.1.0-linux-x86_64.zip
$ sudo unzip protoc-3.1.0-linux-x86_64.zip -d /usr/local

With the required dependencies installed, the Makefile target named binaries will compile the ctr and containerd binaries and place them in the bin/ directory. Using sudo make install will place the binaries in /usr/local/bin. When making any changes to the gRPC API, make generate will use the installed protoc compiler to regenerate the API generated code packages.

Note: A build tag is currently available to disable building the btrfs snapshot driver. Adding BUILDTAGS=no_btrfs to your environment before calling the binaries Makefile target will disable the btrfs driver within the containerd Go build.

Vendoring of external imports uses the vndr tool which uses a simple config file, vendor.conf, to provide the URL and version or hash details for each vendored import. After modifying vendor.conf run the vndr tool to update the vendor/ directory contents. Combining the vendor.conf update with the changeset in vendor/ after running vndr should become a single commit for a PR which relies on vendored updates.

Please refer to RUNC.md for the currently supported version of runc that is used by containerd.

Releases

containerd will be released with a 1.0 when feature complete and this version will be supported for 1 year with security and bug fixes applied and released.

The upgrade path for containerd is that the 0.0.x patch releases are always backward compatible with its major and minor version. Minor (0.x.0) version will always be compatible with the previous minor release. i.e. 1.2.0 is backwards compatible with 1.1.0 and 1.1.0 is compatible with 1.0.0. There is no compatibility guarantees with upgrades from two minor releases. i.e. 1.0.0 to 1.2.0.

There are not backwards compatibility guarantees with upgrades to major versions. i.e 1.0.0 to 2.0.0. Each major version will be supported for 1 year with bug fixes and security patches.

Development reports.

Weekly summary on the progress and what is being worked on. https://github.com/containerd/containerd/tree/master/reports

Communication

For async communication and long running discussions please use issues and pull requests on the github repo. This will be the best place to discuss design and implementation.

For sync communication we have a community slack with a #containerd channel that everyone is welcome to join and chat about development.

Slack: https://dockr.ly/community

Copyright ©2016-2017 Docker, Inc. All rights reserved, except as follows. Code is released under the Apache 2.0 license. The README.md file, and files in the "docs" folder are licensed under the Creative Commons Attribution 4.0 International License under the terms and conditions set forth in the file "LICENSE.docs". You may obtain a duplicate copy of the same license, titled CC-BY-SA-4.0, at http://creativecommons.org/licenses/by/4.0/.

Documentation

Index

Constants

View Source 
const DefaultAddress = "/run/containerd/containerd.sock"

DefaultAddress is the default unix socket address

View Source 
const UnknownExitStatus = 255

Variables

This section is empty.

Functions

func GenerateSpec 

func GenerateSpec(opts ...SpecOpts) (*specs.Spec, error)

GenerateSpec will generate a default spec from the provided image for use as a containerd container

func NewRemoteContainerStore 

func NewRemoteContainerStore(client containersapi.ContainersClient) containers.Store

func WithExit 

func WithExit(r *CheckpointTaskInfo) error

func WithPullUnpack 

func WithPullUnpack(client *Client, c *RemoteContext) error

WithPullUnpack is used to unpack an image after pull. This uses the snapshotter, content store, and diff service configured for the client.

func WithRootFSDeletion 

func WithRootFSDeletion(ctx context.Context, client *Client, c containers.Container) error

WithRootFSDeletion deletes the rootfs allocated for the container

func WithSchema1Conversion 

func WithSchema1Conversion(client *Client, c *RemoteContext) error

WithSchema1Conversion is used to convert Docker registry schema 1 manifests to oci manifests on pull. Without this option schema 1 manifests will return a not supported error.

func WithStdinCloser 

func WithStdinCloser(r *IOCloseInfo)

func WithTTY 

func WithTTY(s *specs.Spec) error

Types

type CheckpointTaskInfo 

type CheckpointTaskInfo struct {
	ParentCheckpoint digest.Digest
	Options          interface{}
}

type CheckpointTaskOpts 

type CheckpointTaskOpts func(*CheckpointTaskInfo) error

type Client 

type Client struct {
	// contains filtered or unexported fields
}

Client is the client to interact with containerd and its various services using a uniform interface

func New 

func New(address string, opts ...ClientOpt) (*Client, error)

New returns a new containerd client that is connected to the containerd instance provided by address

func NewWithConn 

func NewWithConn(conn *grpc.ClientConn, opts ...ClientOpt) (*Client, error)

NewWithConn returns a new containerd client that is connected to the containerd instance provided by the connection

func (*Client) Close 

func (c *Client) Close() error

Close closes the clients connection to containerd

func (*Client) ContainerService 

func (c *Client) ContainerService() containers.Store

func (*Client) Containers 

func (c *Client) Containers(ctx context.Context, filters ...string) ([]Container, error)

Containers returns all containers created in containerd

func (*Client) ContentStore 

func (c *Client) ContentStore() content.Store

func (*Client) DiffService 

func (c *Client) DiffService() diff.DiffService

func (*Client) EventService 

func (c *Client) EventService() eventsapi.EventsClient

func (*Client) GetImage 

func (c *Client) GetImage(ctx context.Context, ref string) (Image, error)

GetImage returns an existing image

func (*Client) HealthService 

func (c *Client) HealthService() grpc_health_v1.HealthClient

func (*Client) ImageService 

func (c *Client) ImageService() images.Store

func (*Client) IsServing 

func (c *Client) IsServing(ctx context.Context) (bool, error)

func (*Client) ListImages 

func (c *Client) ListImages(ctx context.Context) ([]Image, error)

ListImages returns all existing images

func (*Client) LoadContainer 

func (c *Client) LoadContainer(ctx context.Context, id string) (Container, error)

func (*Client) NamespaceService 

func (c *Client) NamespaceService() namespacesapi.NamespacesClient

func (*Client) NewContainer 

func (c *Client) NewContainer(ctx context.Context, id string, opts ...NewContainerOpts) (Container, error)

NewContainer will create a new container in container with the provided id the id must be unique within the namespace

func (*Client) Pull 

func (c *Client) Pull(ctx context.Context, ref string, opts ...RemoteOpts) (Image, error)

func (*Client) Push 

func (c *Client) Push(ctx context.Context, ref string, desc ocispec.Descriptor, opts ...RemoteOpts) error

func (*Client) SnapshotService 

func (c *Client) SnapshotService(snapshotterName string) snapshot.Snapshotter

func (*Client) TaskService 

func (c *Client) TaskService() tasks.TasksClient

func (*Client) Version 

func (c *Client) Version(ctx context.Context) (Version, error)

func (*Client) VersionService 

func (c *Client) VersionService() versionservice.VersionClient

type ClientOpt 

type ClientOpt func(c *clientOpts) error

func WithDefaultNamespace 

func WithDefaultNamespace(ns string) ClientOpt

func WithDialOpts 

func WithDialOpts(opts []grpc.DialOption) ClientOpt

WithDialOpts allows grpc.DialOptions to be set on the connection

type Container 

type Container interface {
	ID() string
	Info() containers.Container
	Delete(context.Context, ...DeleteOpts) error
	NewTask(context.Context, IOCreation, ...NewTaskOpts) (Task, error)
	Spec() (*specs.Spec, error)
	Task(context.Context, IOAttach) (Task, error)
	Image(context.Context) (Image, error)
	Labels(context.Context) (map[string]string, error)
	SetLabels(context.Context, map[string]string) (map[string]string, error)
}

type DeleteOpts 

type DeleteOpts func(context.Context, *Client, containers.Container) error

type FIFOSet 

type FIFOSet struct {
	// Dir is the directory holding the task fifos
	Dir          string
	In, Out, Err string
	Terminal     bool
}

func NewFifos 

func NewFifos() (*FIFOSet, error)

NewFifos returns a new set of fifos for the task

type IO 

type IO struct {
	Terminal bool
	Stdin    string
	Stdout   string
	Stderr   string
	// contains filtered or unexported fields
}

func Stdio 

func Stdio() (*IO, error)

Stdio returns an IO implementation to be used for a task that outputs the container's IO as the current processes Stdio

func StdioTerminal 

func StdioTerminal() (*IO, error)

StdioTerminal will setup the IO for the task to use a terminal

func (*IO) Cancel 

func (i *IO) Cancel()

func (*IO) Close 

func (i *IO) Close() error

func (*IO) Wait 

func (i *IO) Wait()

type IOAttach 

type IOAttach func(*FIFOSet) (*IO, error)

func WithAttach 

func WithAttach(stdin io.Reader, stdout, stderr io.Writer) IOAttach

type IOCloseInfo 

type IOCloseInfo struct {
	Stdin bool
}

type IOCloserOpts 

type IOCloserOpts func(*IOCloseInfo)

type IOCreation 

type IOCreation func() (*IO, error)

func NewIO 

func NewIO(stdin io.Reader, stdout, stderr io.Writer) IOCreation

func NewIOWithTerminal 

func NewIOWithTerminal(stdin io.Reader, stdout, stderr io.Writer, terminal bool) IOCreation

type Image 

type Image interface {
	Name() string
	Target() ocispec.Descriptor

	Unpack(context.Context, string) error
}

type NewContainerOpts 

type NewContainerOpts func(ctx context.Context, client *Client, c *containers.Container) error

func WithCheckpoint 

func WithCheckpoint(desc v1.Descriptor, rootfsID string) NewContainerOpts

func WithContainerLabels 

func WithContainerLabels(labels map[string]string) NewContainerOpts

WithContainerLabels adds the provided labels to the container

func WithExistingRootFS 

func WithExistingRootFS(id string) NewContainerOpts

WithExistingRootFS uses an existing root filesystem for the container

func WithImage 

func WithImage(i Image) NewContainerOpts

func WithNewReadonlyRootFS 

func WithNewReadonlyRootFS(id string, i Image) NewContainerOpts

WithNewReadonlyRootFS allocates a new snapshot to be used by the container as the root filesystem in read-only mode

func WithNewRootFS 

func WithNewRootFS(id string, i Image) NewContainerOpts

WithNewRootFS allocates a new snapshot to be used by the container as the root filesystem in read-write mode

func WithRuntime 

func WithRuntime(name string) NewContainerOpts

WithRuntime allows a user to specify the runtime name and additional options that should be used to create tasks for the container

func WithSnapshotter 

func WithSnapshotter(name string) NewContainerOpts

func WithSpec 

func WithSpec(spec *specs.Spec) NewContainerOpts

type NewTaskOpts 

type NewTaskOpts func(context.Context, *Client, *TaskInfo) error

func WithTaskCheckpoint 

func WithTaskCheckpoint(desc v1.Descriptor) NewTaskOpts

type Process 

type Process interface {
	Pid() uint32
	Start(context.Context) error
	Delete(context.Context) (uint32, error)
	Kill(context.Context, syscall.Signal) error
	Wait(context.Context) (uint32, error)
	CloseIO(context.Context, ...IOCloserOpts) error
	Resize(ctx context.Context, w, h uint32) error
	IO() *IO
}

type RemoteContext 

type RemoteContext struct {
	// Resolver is used to resolve names to objects, fetchers, and pushers.
	// If no resolver is provided, defaults to Docker registry resolver.
	Resolver remotes.Resolver

	// Unpack is done after an image is pulled to extract into a snapshotter.
	// If an image is not unpacked on pull, it can be unpacked any time
	// afterwards. Unpacking is required to run an image.
	Unpack bool

	// Snapshotter used for unpacking
	Snapshotter string

	// BaseHandlers are a set of handlers which get are called on dispatch.
	// These handlers always get called before any operation specific
	// handlers.
	BaseHandlers []images.Handler

	// ConvertSchema1 is whether to convert Docker registry schema 1
	// manifests. If this option is false then any image which resolves
	// to schema 1 will return an error since schema 1 is not supported.
	ConvertSchema1 bool
}

RemoteContext is used to configure object resolutions and transfers with remote content stores and image providers.

type RemoteOpts 

type RemoteOpts func(*Client, *RemoteContext) error

func WithImageHandler 

func WithImageHandler(h images.Handler) RemoteOpts

WithImageHandler adds a base handler to be called on dispatch.

func WithPullSnapshotter 

func WithPullSnapshotter(snapshotterName string) RemoteOpts

WithPullSnapshotter specifies snapshotter name used for unpacking

func WithResolver 

func WithResolver(resolver remotes.Resolver) RemoteOpts

WithResolver specifies the resolver to use.

type SpecOpts 

type SpecOpts func(s *specs.Spec) error

func WithHostNamespace 

func WithHostNamespace(ns specs.LinuxNamespaceType) SpecOpts

func WithImageConfig 

func WithImageConfig(ctx context.Context, i Image) SpecOpts

func WithLinuxNamespace 

func WithLinuxNamespace(ns specs.LinuxNamespace) SpecOpts

WithLinuxNamespace uses the passed in namespace for the spec. If a namespace of the same type already exists in the spec, the existing namespace is replaced by the one provided.

func WithProcessArgs 

func WithProcessArgs(args ...string) SpecOpts

type Task 

type Task interface {
	Pid() uint32
	Delete(context.Context) (uint32, error)
	Kill(context.Context, syscall.Signal) error
	Pause(context.Context) error
	Resume(context.Context) error
	Start(context.Context) error
	Status(context.Context) (TaskStatus, error)
	Wait(context.Context) (uint32, error)
	Exec(context.Context, string, *specs.Process, IOCreation) (Process, error)
	Pids(context.Context) ([]uint32, error)
	CloseIO(context.Context, ...IOCloserOpts) error
	Resize(ctx context.Context, w, h uint32) error
	IO() *IO
	Checkpoint(context.Context, ...CheckpointTaskOpts) (v1.Descriptor, error)
	Update(context.Context, ...UpdateTaskOpts) error
}

type TaskInfo 

type TaskInfo struct {
	Checkpoint *types.Descriptor
	Options    interface{}
}

type TaskStatus 

type TaskStatus string
const (
	Running TaskStatus = "running"
	Created TaskStatus = "created"
	Stopped TaskStatus = "stopped"
	Paused  TaskStatus = "paused"
	Pausing TaskStatus = "pausing"
)

type UpdateTaskInfo 

type UpdateTaskInfo struct {
	Resources interface{}
}

type UpdateTaskOpts 

type UpdateTaskOpts func(context.Context, *Client, *UpdateTaskInfo) error

func WithResources 

func WithResources(resources *specs.LinuxResources) UpdateTaskOpts

type Version 

type Version struct {
	Version  string
	Revision string
}

Source Files

View all Source files

Directories

Path Synopsis
api
services/containers/v1
Package containers is a generated protocol buffer package.
 Package containers is a generated protocol buffer package.
services/content/v1
Package content is a generated protocol buffer package.
 Package content is a generated protocol buffer package.
services/diff/v1
Package diff is a generated protocol buffer package.
 Package diff is a generated protocol buffer package.
services/events/v1
Package events is a generated protocol buffer package.
 Package events is a generated protocol buffer package.
services/images/v1
Package images is a generated protocol buffer package.
 Package images is a generated protocol buffer package.
services/namespaces/v1
Package namespaces is a generated protocol buffer package.
 Package namespaces is a generated protocol buffer package.
services/snapshot/v1
Package snapshot is a generated protocol buffer package.
 Package snapshot is a generated protocol buffer package.
services/tasks/v1
Package tasks is a generated protocol buffer package.
 Package tasks is a generated protocol buffer package.
services/version/v1
Package version is a generated protocol buffer package.
 Package version is a generated protocol buffer package.
types
Package types is a generated protocol buffer package.
 Package types is a generated protocol buffer package.
types/task
Package task is a generated protocol buffer package.
 Package task is a generated protocol buffer package.
compression
cmd
containerd
containerd-shim
ctr
protoc-gen-gogoctrd
Package errdefs defines the common errors used throughout containerd packages.
 Package errdefs defines the common errors used throughout containerd packages.
Package filters defines a syntax and parser that can be used for the filtration of items across the containerd API.
 Package filters defines a syntax and parser that can be used for the filtration of items across the containerd API.
fs
fstest
Package gc experiments with providing central gc tooling to ensure deterministic resource removal within containerd.
 Package gc experiments with providing central gc tooling to ensure deterministic resource removal within containerd.
Package identifiers provides common validation for identifiers and keys across containerd.
 Package identifiers provides common validation for identifiers and keys across containerd.
runcopts
Package runcopts is a generated protocol buffer package.
 Package runcopts is a generated protocol buffer package.
shim
shim/v1
Package shim is a generated protocol buffer package.
 Package shim is a generated protocol buffer package.
metrics
cgroups
lookup_test
Package namespaces provides tools for working with namespaces across containerd.
 Package namespaces provides tools for working with namespaces across containerd.
Package oci provides basic operations for manipulating OCI images.
 Package oci provides basic operations for manipulating OCI images.
Package progress assists in displaying human readable progress information.
 Package progress assists in displaying human readable progress information.
docker
docker/schema1
services
containers
content
diff
events
healthcheck
images
namespaces
snapshot
tasks
version
btrfs
naive
overlay
storage
Package storage provides a metadata storage implementation for snapshot drivers.
 Package storage provides a metadata storage implementation for snapshot drivers.
storage/proto
Package proto is a generated protocol buffer package.
 Package proto is a generated protocol buffer package.
testsuite
windows
Package sys provides access to the Get Child and Set Child prctl flags.
 Package sys provides access to the Get Child and Set Child prctl flags.
hcs
pid

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