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// Libcontainer provides a native Go implementation for creating containers
// with namespaces, cgroups, capabilities, and filesystem access controls.
// It allows you to manage the lifecycle of the container performing additional operations
// after the container is created.
package libcontainer
import (
"os"
"github.com/opencontainers/runc/libcontainer/configs"
)
// The status of a container.
type Status int
const (
// The container exists and is running.
Running Status = iota + 1
// The container exists, it is in the process of being paused.
Pausing
// The container exists, but all its processes are paused.
Paused
// The container exists, but its state is saved on disk
Checkpointed
// The container does not exist.
Destroyed
)
// State represents a running container's state
type State struct {
// ID is the container ID.
ID string `json:"id"`
// InitProcessPid is the init process id in the parent namespace.
InitProcessPid int `json:"init_process_pid"`
// InitProcessStartTime is the init process start time.
InitProcessStartTime string `json:"init_process_start"`
// Path to all the cgroups setup for a container. Key is cgroup subsystem name
// with the value as the path.
CgroupPaths map[string]string `json:"cgroup_paths"`
// NamespacePaths are filepaths to the container's namespaces. Key is the namespace type
// with the value as the path.
NamespacePaths map[configs.NamespaceType]string `json:"namespace_paths"`
// Config is the container's configuration.
Config configs.Config `json:"config"`
// Container's standard descriptors (std{in,out,err}), needed for checkpoint and restore
ExternalDescriptors []string `json:"external_descriptors,omitempty"`
}
// A libcontainer container object.
//
// Each container is thread-safe within the same process. Since a container can
// be destroyed by a separate process, any function may return that the container
// was not found.
type Container interface {
// Returns the ID of the container
ID() string
// Returns the current status of the container.
//
// errors:
// ContainerDestroyed - Container no longer exists,
// Systemerror - System error.
Status() (Status, error)
// State returns the current container's state information.
//
// errors:
// Systemerror - System error.
State() (*State, error)
// Returns the current config of the container.
Config() configs.Config
// Returns the PIDs inside this container. The PIDs are in the namespace of the calling process.
//
// errors:
// ContainerDestroyed - Container no longer exists,
// Systemerror - System error.
//
// Some of the returned PIDs may no longer refer to processes in the Container, unless
// the Container state is PAUSED in which case every PID in the slice is valid.
Processes() ([]int, error)
// Returns statistics for the container.
//
// errors:
// ContainerDestroyed - Container no longer exists,
// Systemerror - System error.
Stats() (*Stats, error)
// Set cgroup resources of container as configured
//
// We can use this to change resources when containers are running.
//
// errors:
// Systemerror - System error.
Set(config configs.Config) error
// Start a process inside the container. Returns error if process fails to
// start. You can track process lifecycle with passed Process structure.
//
// errors:
// ContainerDestroyed - Container no longer exists,
// ConfigInvalid - config is invalid,
// ContainerPaused - Container is paused,
// Systemerror - System error.
Start(process *Process) (err error)
// Checkpoint checkpoints the running container's state to disk using the criu(8) utility.
//
// errors:
// Systemerror - System error.
Checkpoint(criuOpts *CriuOpts) error
// Restore restores the checkpointed container to a running state using the criu(8) utiity.
//
// errors:
// Systemerror - System error.
Restore(process *Process, criuOpts *CriuOpts) error
// Destroys the container after killing all running processes.
//
// Any event registrations are removed before the container is destroyed.
// No error is returned if the container is already destroyed.
//
// errors:
// Systemerror - System error.
Destroy() error
// If the Container state is RUNNING or PAUSING, sets the Container state to PAUSING and pauses
// the execution of any user processes. Asynchronously, when the container finished being paused the
// state is changed to PAUSED.
// If the Container state is PAUSED, do nothing.
//
// errors:
// ContainerDestroyed - Container no longer exists,
// Systemerror - System error.
Pause() error
// If the Container state is PAUSED, resumes the execution of any user processes in the
// Container before setting the Container state to RUNNING.
// If the Container state is RUNNING, do nothing.
//
// errors:
// ContainerDestroyed - Container no longer exists,
// Systemerror - System error.
Resume() error
// NotifyOOM returns a read-only channel signaling when the container receives an OOM notification.
//
// errors:
// Systemerror - System error.
NotifyOOM() (<-chan struct{}, error)
// Signal sends the provided signal code to the container's initial process.
//
// errors:
// Systemerror - System error.
Signal(s os.Signal) error
}