Shell script to parse specific field's values from a given yaml file and register them as shell variables with the same field name

parse_yaml_to_vars.sh

#!/bin/bash
## Based on https://gist.github.com/pkuczynski/8665367
## derived from:
##    https://gist.github.com/epiloque/8cf512c6d64641bde388
##    https://gist.github.com/DinoChiesa/3e3c3866b51290f31243

YAML_FILE=test.yaml
debug=1

function parse_yaml_values() {
  fields=('development_adapter' 'development_authentication_class_parameters_attributes' 'development_roles')
  parse_yaml ${YAML_FILE}  
  echo "variable development_adapter: ${development_adapter[*]}"
  echo "variable development_roles: ${development_roles[*]}"
  echo "variable development_authentication_class_parameters_attributes: ${development_authentication_class_parameters_attributes[*]}"
}

# Based on https://gist.github.com/pkuczynski/8665367
#
# Works for arrays of hashes, and some hashes with arrays
# Variable names will be underscore delimitted based on nested parent names
# Send in yaml file as first argument and create a global array named $fields 
# with necessary yaml field names fully underscore delimitted to match nesting
# then this will register those variables into the shell's scope if they exist in Yaml
# $VERBOSE=1 will also print the full values
# Defaults to indent of 4 so d=4
# To use with indent of 2 change d to 2
function parse_yaml() {
    local s
    local w
    local fs
    local d
    s='[[:space:]]*' 
    w='[a-zA-Z0-9_]*' 
    fs="$(echo @|tr @ '\034')" 
    d=4
    eval $(
      sed -ne "s|^\($s\)\($w\)$s:$s\"\(.*\)\"$s\$|\1$fs\2$fs\3|p" \
            -e "s|^\($s\)-\?$s\($w\)$s[:-]$s\(.*\)$s\$|\1$fs\2$fs\3|p" $1 | 
      awk -F"$fs"  -v names="${fields[*]}" '
      BEGIN { split(names,n," ") }
      { sc=length($1) % "'$d'"; 
        if ( sc == 0 ) {
          indent = length($1)/"'$d'"
        } else { 
          indent = (length($1)+("'$d'"-sc))/"'$d'" 
        }
        vname[indent] = $2;
        for (i in vname) {if (i > indent){ delete vname[i];}}
        if (length($3) > 0 ) {
          vn=""; 
          for (i=0; i<indent; i++) {
            if (length(vname[i]) > 0) {vn=(vn)(vname[i])("_");}
          }
          ap=""; 
          if($2 ~ /^ *$/ && vn ~ /_$/) { vn=substr(vn,1,length(vn)-1);ap="+" }
          for ( name in  n ) {
            if ( $2 == n[name] || vn == n[name] || (vn)($2) == n[name]) {
              printf("%s%s%s=(\"%s\")\n", vn, $2, ap, $3);
              if ("'"$debug"'" == "1"){
                printf(";logdebug %s%s%s=\\(\\\"%s\\\"\\);", vn, $2, ap, $3); 
              }
            }
          }
        }
      }'  
    )
}

parse_yaml_values

test.yaml

development:
  adapter: mysql2
  encoding: utf8
  database: my_database
  username: root
  authentication:
    - class: withname
      parameters:
        - attributes : 
            - foo
            - bar,baz
  roles:
    - admin
    - developer
    - guest
  password:
  users:
    - 
      name: pineapple
      role: admin
    -
      name: umbrella
      role: developer