nsinit
is a cli application which demonstrates the use of libcontainer.
It is able to spawn new containers or join existing containers.
First add the libcontainer/vendor
into your GOPATH. It's because libcontainer vendors all its dependencies, so it can be built predictably.
export GOPATH=$GOPATH:/your/path/to/libcontainer/vendor
Then get into the nsinit folder and get the imported file. Use make
command to make the nsinit binary.
cd libcontainer/nsinit go get make
We have finished compiling the nsinit package, but a root filesystem must be provided for use along with a container configuration file.
Choose a proper place to run your container. For example we use /busybox
.
mkdir /busybox curl -sSL 'https://github.com/jpetazzo/docker-busybox/raw/buildroot-2014.11/rootfs.tar' | tar -xC /busybox
Then you may need to write a configuration file named container.json
in the /busybox
folder. Environment, networking, and different capabilities for the container are specified in this file. The configuration is used for each process executed inside the container.
See the sample_configs
folder for examples of what the container configuration should look like.
cp libcontainer/sample_configs/minimal.json /busybox/container.json cd /busybox
You can customize container.json
per your needs. After that, nsinit is ready to work.
To execute /bin/bash
in the current directory as a container just run the following as root:
nsinit exec --tty --config container.json /bin/bash
If you wish to spawn another process inside the container while your current bash session is running, run the same command again to get another bash shell (or change the command). If the original process (PID 1) dies, all other processes spawned inside the container will be killed and the namespace will be removed.
You can identify if a process is running in a container by looking to see if state.json
is in the root of the directory.
You may also specify an alternate root directory from where the container.json
file is read and where the state.json
file will be saved.