d

my docker container practice

precondition

you need to install docker and iptables commandline tools

enable ip forwarding

sysctl net.ipv4.conf.all.forwarding=1

install

go get github.com/ejunjsh/d/cmd/d

usage

NAME:
   d - a simple container runtime implementation.
         The purpose of this project is to learn how docker works and how to write a docker by ourselves
         Enjoy it, just for fun.

USAGE:
   d [global options] command [command options] [arguments...]

VERSION:
   0.0.0

COMMANDS:
     init     Init container process run user's process in container. Do not call it outside
     run      Create a container with namespace and cgroups limit ie: d run -ti [image] [command]
     ps       list all the containers
     exec     exec a command into container
     rm       remove unused containers
     network  container network commands
     install  install an image into d
     help, h  Shows a list of commands or help for one command

GLOBAL OPTIONS:
   --help, -h     show help
   --version, -v  print the version

example

notice: this example is run at Ubuntu 18.04.2 LTS and the d is tested in this environment only.

I'm not sure if d is compatible all the linux distribution.

create nginx container

# docker create nginx
Unable to find image 'nginx:latest' locally
latest: Pulling from library/nginx
f7e2b70d04ae: Pull complete 
08dd01e3f3ac: Pull complete 
d9ef3a1eb792: Pull complete 
Digest: sha256:98efe605f61725fd817ea69521b0eeb32bef007af0e3d0aeb6258c6e6fe7fc1a
Status: Downloaded newer image for nginx:latest
a46332a8ebfae2c83365affbdfe2cd285894c85563d6c898665816f3b7609b47

notice the last line of output, it is a container id

generate tar archive

# docker export a46332a8ebfae2c83365affbdfe2cd285894c85563d6c898665816f3b7609b47 > nginx.tar

use the container id to generate the tar

install tar archive into d

# d install nginx.tar

run a container with d

# d run -i nginx bash
missing mydocker_pid env skip nsenter
{"level":"info","msg":"createTty true","time":"2019-03-13T17:39:00+08:00"}
{"level":"info","msg":"dirs=/var/lib/d/c/1672401789/writeLayer:/var/lib/d/i/nginx","time":"2019-03-13T17:39:00+08:00"}
missing mydocker_pid env skip nsenter
{"level":"info","msg":"command all is bash","time":"2019-03-13T17:39:00+08:00"}
{"level":"info","msg":"init come on","time":"2019-03-13T17:39:00+08:00"}
{"level":"info","msg":"Current location is /var/lib/d/c/1672401789/mnt","time":"2019-03-13T17:39:00+08:00"}
{"level":"info","msg":"Find path /bin/bash","time":"2019-03-13T17:39:00+08:00"}
root@1672401789:/#

you will see it returns a bash and the host name is the container name 1672401789

reference

https://github.com/xianlubird/mydocker

ejunjsh / d

d