matrix-from-json.sh

#!/bin/bash

path_to_file="$1"

# escape human readable multi line json
# to format usable by github fromJSON.
# see https://github.com/actions/toolkit/issues/403
# and https://github.com/actions/toolkit/blob/master/packages/core/src/command.ts#L92
JSON=$(cat "$path_to_file")
JSON="${JSON//'%'/'%25'}"
JSON="${JSON//$'\n'/'%0A'}"
JSON="${JSON//$'\r'/'%0D'}"
# enable the JSON to use any environment var
# replace the = sign with a space and turn into array
for env_var in $(printenv); do
  read -ra arr <<< "${env_var//=/ }"
  JSON="${JSON//\$${arr[0]}/"${arr[1]}"}"
done

# return a value
echo "::set-output name=matrix::$JSON"