lctn is a simple command line program to run a process in a linux container. It focuses on a brief golang code description of how to implement a linux container runtime.
Be sure to run as a root user since creating namespace requires SYS_ADMIN capability.
$ go get github.com/chenchun/lctn
$ cd $GOPATH/src/github.com/chenchun/lctn
$ make
github.com/chenchun/lctn
# run the following command to exec a shell inside a container
$ bin/lctn -logtostderr -root `pwd`/rootfs /bin/sh
/ # env
SHLVL=1
PATH=/sbin:/bin:/usr/sbin:/usr/bin
PWD=/
/ # ls
bin dev etc hello lib linuxrc proc sbin sys usr var
/ # exit
Usage of ./lctn [Flags] Command [Argument ...]:
-alsologtostderr
log to standard error as well as files
-init
is it the init process of container. (This flag is used by lctn internally)
-log_backtrace_at value
when logging hits line file:N, emit a stack trace
-log_dir string
If non-empty, write log files in this directory
-logtostderr
log to standard error instead of files
-root string
the root directory of container
-stderrthreshold value
logs at or above this threshold go to stderr
-v value
log level for V logs
-vmodule value
comma-separated list of pattern=N settings for file-filtered logging
Command:
The init command of container
Argument:
The Arguments of container
Examples:
lctn -logtostderr -root ./rootfs /bin/sh
rootfs directory in this repository comes from https://hub.docker.com/r/chenchun/hello/.
You can easily build your own rootfs from a docker image.
$ mkdir rootfs && cd rootfs
$ CID=$(docker run -d $image)
$ docker export $CID | tar xf -