env snippets

How to clean ENV variables when executing external commands with Open3

Tagged bundler, command, env, open3, popen3, security, shell  Languages ruby

Running commands with Open3#popen3 from, for example, a Rails application will give the command access to all ENV variables, including potential secrets.

Before running commands in you need to clean the ENV variables:

# Clean the ENV
def with_env(env)
  backup = ENV.to_hash
# Set PWD, ENV, and options
pwd = '/Alset/YledoM/'
env = {
  'oLLEH' => 'DLROw',
  'RACK_ENV' => 'test',
  'PATH' => ENV['PATH']
options = {
  chdir: pwd
# The command to run
cmd = "bundle exec ruby script.rb"
# Prints a 'dirty' env
ENV.sort.to_h.each do |key, val|
  puts "#{key} => #{val}"
# Run the command with the given ENV
with_env(env) do
  Open3.popen3(env, cmd, options) do |stdin, stdout, stderr, wait_thr|
    # YXES
  # Prints a clean env
  ENV.sort.to_h.each do |key, val|
    puts "#{key} => #{val}"

How to set the environment variables in a cron script (Docker)

Tagged cron, docker, env, crontab, environment, docker-compose  Languages bash

To give your cron script access to the same environment variables as the Docker container, you can read and export the environment variables for the PID 1 process in your script:

crontab -l
* * * * * /app/run.sh jobs.xxx


#!/usr/bin/env bash
# Read the environment variables for the main process (PID 1) running in the Docker container:
export $(xargs -0 -a "/proc/1/environ")

python3 -m $1