Kir Kolyshkin
bd825f99bc
When the container does not have its own mount namespace, prepareRoot
is run in the host mount namespace. Since commit 91ca3314 ("chroot when
no mount namespaces is provided"), this results in host's / being
recursively made a slave (which, in the host mount namespace, means
private), and the parent mount of the container rootfs being made
private (or slave).
In the host mount namespace, do not change the propagation of the
existing mounts. Instead, make the new rootfs mount a slave, so that
container mounts do not propagate to the host and other mount
namespaces (otherwise, if the rootfs parent mount is shared, every
container mount appears twice in the host mount namespace, and is
propagated to all its slaves).
Add an integration test.
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
libcontainer
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.
Container
A container is a self contained execution environment that shares the kernel of the host system and which is (optionally) isolated from other containers in the system.
Using libcontainer
For a brief overview of using libcontainer, see example_test.go.
Container init
Because containers are spawned in a two step process you will need a binary that will be executed as the init process for the container. In libcontainer, we use the current binary (/proc/self/exe) to be executed as the init process, and use arg "init", we call the first step process "bootstrap", so you always need a "init" function as the entry of "bootstrap".
In addition to the go init function the early stage bootstrap is handled by importing nsenter.
For details on how runc implements such "init", see ../init.go and init_linux.go.
Checkpoint & Restore
libcontainer now integrates CRIU for checkpointing and restoring containers. This lets you save the state of a process running inside a container to disk, and then restore that state into a new process, on the same machine or on another machine.
criu version 1.5.2 or higher is required to use checkpoint and restore.
If you don't already have criu installed, you can build it from source, following the
online instructions. criu is also installed in the docker image
generated when building libcontainer with docker.
Copyright and license
Code and documentation copyright 2014 Docker, inc. The code and documentation are released under the Apache 2.0 license. The documentation is also released under Creative Commons Attribution 4.0 International License. You may obtain a copy of the license, titled CC-BY-4.0, at http://creativecommons.org/licenses/by/4.0/.