Elastic Beanstalk environment variables for Docker host

Question

I have an EB env with Docker web app (rails) properly deployed. I set several EB env variables and they are properly visible in the container. Now - I'd like these EB env variables to be visible to the EC2 instance host, so that I can use them in the docker build process. However, they are not exposed to the docker host, only to the container.
How do I expose EB env variables to the Docker host?

Answer 1

I ran into the same issue, but needed the environment variables to be available during the execution of a post-deployment Bash script.

Since the jq parser is available on the (current) Amazon Linux AMIs, I was able to acheive something similar using it to parse the JSON and then export the environment variables on the host (this is an excerpt from an ebextensions config file):

files:
  "/opt/elasticbeanstalk/hooks/appdeploy/post/export_env_vars_on_host.sh":
  mode: "000755"
  owner: root
  group: root
  content: |
    #!/usr/bin/env bash
    echo Defaults:root \!requiretty >> /etc/sudoers
    for envvar in `jq '.optionsettings | {"aws:elasticbeanstalk:application:environment"}[] | .[]' /opt/elasticbeanstalk/deploy/configuration/containerconfiguration`
    do
      temp="${envvar#\"}";
      temp="${temp/=/=\"}";
      export temp;
    done

Answer 2

This was a though one, so I'm posting my solution for those who encounter this.
Elastic Beanstalk Docker instance does not expose the environment variables to the docker host. It does that only to the docker container.
If you'd like to get the env variables on the host, they are located at /opt/elasticbeanstalk/deploy/configuration/containerconfiguration.
This is one large JSON file, conveniently disobeying the JSON structure for the env vars.
I wrote a small ruby script to parse it and extract the env vars from it:

require 'json'
container_config = JSON.parse(File.read('/opt/elasticbeanstalk/deploy/configuration/containerconfiguration'))
raw_vars =  container_config['optionsettings']['aws:elasticbeanstalk:application:environment']
envs = ''
raw_vars.each do |raw_var|
  pair = raw_var.split('=')
  envs << "export #{pair[0]}=#{pair[1]}\n" if pair[1]
end
puts envs

this script yields a set of export commands to console that sets the env vars. I adapted it a bit to write ENV commands into my Dockerfile.