Convert configuration YAML file into properties file or shell environment variables

c.py

#!/usr/bin/python3
import os
import re
import yaml
import sys

if not os.getenv("CONFIG_FILE"):
    print("Usage:")
    print("$ CONFIG_FILE=the/config.yaml " + sys.argv[0] + "   < exports to yaml by default")
    print("$ CONFIG_FILE=the/config.yaml " + sys.argv[0] + " yaml")
    print("$ CONFIG_FILE=the/config.yaml " + sys.argv[0] + " bash")
    print("$ CONFIG_FILE=the/config.yaml " + sys.argv[0] + " bash CONFIG   < Adds a leading 'CONFIG_' to all vars")
    sys.exit(1)

data = yaml.load(open(os.getenv("CONFIG_FILE"),'r'))

FMT = sys.argv[1].lower() if len(sys.argv)>1 else "yaml"
STARTWITH = sys.argv[2].lower() if len(sys.argv)==3 else ""

# Display name and value with format depending on type
# Values list are joined with commas
# Values in shell are protected from expansion
# Shell: caution: remember to quote them in shell to preserve \n and *
# Force variables, in any case, to contain ony digits, a-z and underscores
def display_var(k, v):
  format = "{},{}"
  if FMT == "yaml": format = "{}: {}"
  if FMT == "bash": format = "export {}=\"{}\""

  if type(v) is list: v = ",".join(v)

  if FMT == "bash" and isinstance(v,str):
      v = v.replace("$","\$")
  k = re.sub("[^a-zA-Z0-9_]", "_", k)

  print(format.format(k, v))

def print_level(data,start_in="", start_with=""):
    start_in = start_in if not start_with else start_with
    for subkey in data.keys():
      if hasattr(data[subkey],'items'):
        restart_in = start_in + "_" + subkey if start_in else subkey
        print_level(data[subkey],restart_in)
      else:
        display_var((start_in[len(start_with):]+"_"+subkey).upper(), data[subkey])

print_level(data,start_with=STARTWITH)

read.me

I use yaml files for global environments configuration.
Each environment (dev, prod, stage) has its own identical 
structured yaml file with the environment's values.

To use them into bash scripts or containers and docker-compose 
files as environment variables I just wrote this little script
to generate the proper output.

CAUTION: It modifies yaml keys in order to make them usable. 
This feature will force everybody use nice names

Example input:
cfg:
  google:
    ownership_verification:
      stage.domain.com:
        upload_file_name: googlec862b21dd0613842e.html
        
Example output (bash):
# Variable name modified, original: CFG_GOOGLE_OWNERSHIP_VERIFICATION_STAGE.DOMAIN.COM_UPLOAD_FILE_NAME
export CFG_GOOGLE_OWNERSHIP_VERIFICATION_STAGE_DOMAIN_COM_UPLOAD_FILE_NAME="googlec862b21dd0613842e.html"

Example output (yaml):
# Variable name modified, original: CFG_GOOGLE_OWNERSHIP_VERIFICATION_STAGE.DOMAIN.COM_UPLOAD_FILE_NAME
CFG_GOOGLE_OWNERSHIP_VERIFICATION_STAGE_DOMAIN_COM_UPLOAD_FILE_NAME: googlec862b21dd0613842e.html