runc/nsinit/README.md

## nsinit

`nsinit` is a cli application which demonstrates the use of libcontainer.  
It is able to spawn new containers or join existing containers.  

### How to build?

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**:

```bash
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.