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Zenv

Zenv is container based virtual environments. The main goal of Zenv is to simplify access to applications inside container, making it seamless in use like native (host-machine) applications

Usage

> zenv init
Zenv created!

> # run `ls` command inside contaner
> ze ls

Motivation

As a developer, when set up a project locally, I usually need to install additional applications on the system. Of course, modern package managers such as poetry, pipenv, npm, cargo, ext, perfectly solve for us most of the problems with dependencies within a single stack of technologies. But they do not allow to solve the problem with the installation of system libraries. If you have a lot of projects that require different versions of system libraries, then you have problems

In production, this problem has long been solved by container insulation, and as a rule, it is a Docker. Therefore, many of my colleagues use docker-images and docker-compose, not only to run services in a production environment but also to develop and debug programs on a local machine

Unfortunately, there are several problems along the way:

  • Some of your familiar utilities may not be preinstalled in the container
  • If you try to install packages in the process, you will encounter the lack of necessary rights
  • Forget about debugging with print
  • The main thing is lost the usual experience, you can not use your favorite customized shell

Of course, the problems described above are solved by creating a docker image specifically for developing a specific project, zenv just helps to create such containers very simply

Features

  • Simplify: all interaction with the container occurs with one short command: ze

  • Zenv automatically forwarded current directory to the container with the same PWD

  • Zenv automatically forwarded current UserID, GroupID to container

    Therefore, files created in the container have the same rights as those created in the native console and you can also use sudo to get privileges

    > sudo ze <command>

    or

    > sudo !!

  • Zenv can forwarded environment vars as is native

    > MYVAR=LIVE!!!! ze env

  • And of course your could combinate native and containerized commands in Unix pipes

    > ze ls | head -7 | ze tail -5

  • Minimal performance impact

  • Customization: you can additionally control container parameters using Zenvfile

Install

  1. Make sure you have the latest version of Docker installed
  2. For linux, make sure you have your user’s rights are allowed to interact with doker
  3. Make sure that you have python version 3.6 or higher
  4. Execute: 
    > sudo pip install zenv-cli
# or
> sudo pip3 install zenv-cli

How It works

By nature, zenv is a small automated layer over the official docker CLI

init

Command zenv init create Zenvfile in current directory. This file describes the relationship with the docker image and container that will be created to execute isolated commands.

By default, used image is ubuntu: latest. But you can change it by setting -i flag. For example:

> zenv init -i python:latest

Or edit Zenvfile manually

Execute

Command zenv exec <COMMAND> or it shot alias ze <COMMAND> run <COMMAND> in a container environment. When running the command:

  • Zenv checks current container status (running, stopped, removed), and up container if need.
  • The container run with the command sleep infinity. Therefore it will be easily accessible
  • UID and GID that ran the command are pushed into the container. Therefor your could use sudo ze <COMMAND>
  • When executing the command, the directory from the path where Zenvfile is located is forwarded to the container as is a current PWD. Therefor your could run ze from deep into directories relative to Zenvfile
  • Environment variables are also thrown into the container as a native. 
    > MYVAR=SUPER ze env

To avoid conflicts between host and container variables, all installed system variables are placed in the blacklist when Zenvfile is created, from which editing can be removed

Other commands

> zenv --help
Usage: zenv [OPTIONS] COMMAND [ARGS]...

  ZENV(Zen-env): Containers manager for developer environment

  Usage:

  > zenv init -i centos:latest & ze cat /etc/redhat-release

Options:
  --help  Show this message and exit.

Commands:
  exec      Call some command inside the container
  info      Show current container info
  init      Initialize Environment: create Zenvfile
  rm        Remove container (will stop the container, if need)
  stop      Stop container
  stop-all  Stop all zenv containers

Example install jupyter notebook

> mkgir notebooks
> cd notebooks
> zenv init -i python:3.7.3

After edit Zenvfile to explode notebook ports. Update ports = [] to ports = ["8888:8888"]

> sudo ze pip install jupyter numpy scipy matplotlib

Run notebook

> ze jupyter notebook --ip 0.0.0.0

launch your browser with url: http://localhost:8888

Also you could add this commands to Zenvfile:

[run]
init_commands = [
  [ "__create_user__"],
  ["pip", "install", "jupyter", "numpy", "scipy", "matplotlib"]
]

[commands]
notebook = ["jupyter", "notebook", "--ip", "0.0.0.0"]

And launch notebook with command

> ze notebook

Zenvfile

[main]
image = "ubuntu:latest"
name = "zenv-project"    # container name
debug = false            # for show docker commands

[run]
command = [ "__sleep__",]
init_commands = [ [ "__create_user__",],]

[exec]
env_file = ""
env_excludes = [ "TMPDIR",]

[run.options]
volume = [ "{zenvfilepath}:{zenvfilepath}:rw",]
detach = "true"
publish = []

[commands]
__sleep__ = [ "sleep", "365d",]
__create_user__ = [ "useradd", "-m", "-r", "-u", "{uid}", "-g", "{gid}", "zenv",]