README
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libcontainer - reference implementation for containers
background
libcontainer specifies configuration options for what a container is. It provides a native Go implementation for using Linux namespaces with no external dependencies. libcontainer provides many convenience functions for working with namespaces, networking, and management.
container
A container is a self contained directory that is able to run one or more processes without
affecting the host system. The directory is usually a full system tree. Inside the directory
a container.json file is placed with the runtime configuration for how the processes
should be contained and ran. Environment, networking, and different capabilities for the
process are specified in this file. The configuration is used for each process executed inside the container.
See the container.json file for what the configuration should look like.
Using this configuration and the current directory holding the rootfs for a process, one can use libcontainer to exec the container. Running the life of the namespace, a pid file
is written to the current directory with the pid of the namespaced process to the external world. A client can use this pid to wait, kill, or perform other operation with the container. If a user tries to run a new process inside an existing container with a live namespace, the namespace will be joined by the new process.
You may also specify an alternate root place where the container.json file is read and where the pid file will be saved.
nsinit
nsinit is a cli application used as the reference implementation of libcontainer. It is able to
spawn or join new containers giving the current directory. To use nsinit cd into a Linux
rootfs and copy a container.json file into the directory with your specified configuration.
To execute /bin/bash in the current directory as a container just run:
nsinit exec /bin/bash
If you wish to spawn another process inside the container while your current bash session is running just run the exact same command again to get another bash shell or change the command. If the original process dies, PID 1, all other processes spawned inside the container will also be killed and the namespace will be removed.
You can identify if a process is running in a container by looking to see if pid is in the root of the directory.
Documentation
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Index ¶
Constants ¶
This section is empty.
Variables ¶
Functions ¶
This section is empty.
Types ¶
type Capabilities ¶
type Capabilities []*Capability
func (Capabilities) Contains ¶
func (c Capabilities) Contains(capp string) bool
Contains returns true if the specified Capability is in the slice
func (Capabilities) Get ¶ added in v0.10.0
func (c Capabilities) Get(capp string) *Capability
type Capability ¶
type Capability struct {
Key string `json:"key,omitempty"`
Value capability.Cap `json:"value,omitempty"`
}
func GetCapability ¶
func GetCapability(key string) *Capability
func (*Capability) String ¶
func (c *Capability) String() string
type Container ¶
type Container struct {
Hostname string `json:"hostname,omitempty"` // hostname
ReadonlyFs bool `json:"readonly_fs,omitempty"` // set the containers rootfs as readonly
NoPivotRoot bool `json:"no_pivot_root,omitempty"` // this can be enabled if you are running in ramdisk
User string `json:"user,omitempty"` // user to execute the process as
WorkingDir string `json:"working_dir,omitempty"` // current working directory
Env []string `json:"environment,omitempty"` // environment to set
Tty bool `json:"tty,omitempty"` // setup a proper tty or not
Namespaces map[string]bool `json:"namespaces,omitempty"` // namespaces to apply
CapabilitiesMask map[string]bool `json:"capabilities_mask,omitempty"` // capabilities to drop
Networks []*Network `json:"networks,omitempty"` // nil for host's network stack
Cgroups *cgroups.Cgroup `json:"cgroups,omitempty"` // cgroups
Context Context `json:"context,omitempty"` // generic context for specific options (apparmor, selinux)
Mounts Mounts `json:"mounts,omitempty"`
}
Container defines configuration options for how a container is setup inside a directory and how a process should be executed
type Mount ¶ added in v0.10.0
type Mount struct {
Type string `json:"type,omitempty"`
Source string `json:"source,omitempty"` // Source path, in the host namespace
Destination string `json:"destination,omitempty"` // Destination path, in the container
Writable bool `json:"writable,omitempty"`
Private bool `json:"private,omitempty"`
}
type Namespace ¶
type Namespace struct {
Key string `json:"key,omitempty"`
Value int `json:"value,omitempty"`
File string `json:"file,omitempty"`
}
func GetNamespace ¶
type Namespaces ¶
type Namespaces []*Namespace
func (Namespaces) Contains ¶
func (n Namespaces) Contains(ns string) bool
Contains returns true if the specified Namespace is in the slice
func (Namespaces) Get ¶ added in v0.10.0
func (n Namespaces) Get(ns string) *Namespace
type Network ¶
type Network struct {
Type string `json:"type,omitempty"` // type of networking to setup i.e. veth, macvlan, etc
Context Context `json:"context,omitempty"` // generic context for type specific networking options
Address string `json:"address,omitempty"`
Gateway string `json:"gateway,omitempty"`
Mtu int `json:"mtu,omitempty"`
}
Network defines configuration for a container's networking stack
The network configuration can be omited from a container causing the container to be setup with the host's networking stack
Source Files
Directories