Read in environmental variables with env command and output the environmental variables as a JSON string. This was build to be used in a minimal Docker environment with only shell scripting access.

env2json

#!/usr/bin/env bash

# To use this with sed the output string needs to be escaped like so:
# ./env2json | sed -e 's/[]\/$*.^|[]/\\&/g'
# Here is an example:
# sed -e "s/{PLACEHOLDER}/$(./env2json | sed -e 's/[]\/$*.^|[]/\\&/g')/" test.conf

# http://www.linuxjournal.com/content/bash-associative-arrays
# http://stackoverflow.com/questions/3112687/how-to-iterate-over-associative-array-in-bash
# http://stackoverflow.com/questions/9449417/how-do-i-assign-the-output-of-a-command-into-an-array
# http://tldp.org/LDP/abs/html/string-manipulation.html
# http://stackoverflow.com/questions/407523/escape-a-string-for-a-sed-replace-pattern

declare -A $( env | awk -F'=' '{print "environment["$1"]="$2}' )

json_environment="{"
for i in "${!environment[@]}"
do
        json_environment=$json_environment"\"${i}\":\"${environment[$i]}\","
done

# remove trailing comma and add finishing curly brace
json_environment="${json_environment%,}}"

echo -n $json_environment