add yaml parsing lightning talk

2020_07_15_51st/lightningtalks/yaml-parsing/example-cli.py

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+#!/usr/bin/env python3
+
+""" YAML one value editor CLI example
+    author: Billy Duong
+
+    Feel free to use/modify/edit this code.
+"""
+
+import sys, subprocess, uuid, argparse
+from ruamel.yaml import YAML
+
+
+# constants
+ACTION_READ = 'READ'
+ACTION_DELETE = 'DELETE'
+ACTION_UPDATE = 'UPDATE'
+ACTION_CHOICES = [ACTION_READ, ACTION_UPDATE, ACTION_DELETE]
+
+
+# setup argument parser
+parser = argparse.ArgumentParser(description='edit values of a yaml file')
+
+parser.add_argument('action', choices=ACTION_CHOICES, help='action executed (READ = output value | UPDATE = update value | DELETE = delete key)')
+parser.add_argument('target_file', help='target file')
+parser.add_argument('key', help='key')
+
+parser.add_argument('-nv', '--new-value', help='new value')
+parser.add_argument('-iw', '--inplace-write', action='store_true', help='writes directly to the file (default is stdout)')
+parser.add_argument('-v', '--verbose', action='store_true', help='additional information')
+
+
+def patch(yamlobj):
+    '''patch yaml object functionality'''
+
+    def get_key(key):
+        data = yamlobj
+        for v in key.split('.'):
+            data = data[v]
+        return data
+
+    def write_key(key, data):
+        target = yamlobj
+        for v in key.split('.')[:-1]:
+            target = target[v]
+        lastkey = key.split('.')[-1]
+        target[lastkey] = data
+
+    def delete_key(key):
+        target = yamlobj
+        for v in key.split('.')[:-1]:
+            target = target[v]
+        lastkey = key.split('.')[-1]
+        del target[lastkey]
+
+    yamlobj.get_key = get_key
+    yamlobj.write_key = write_key
+    yamlobj.delete_key = delete_key
+
+
+if __name__ == '__main__':
+    # parse arguments
+    args = parser.parse_args()
+    filepath = args.target_file
+    key = args.key
+    value = args.new_value
+    action = args.action
+    inplace_write = args.inplace_write
+    VERBOSE = args.verbose
+
+    # parse
+    yaml = YAML() # uses roundtrip parser (keeps comments and order)
+    result = yaml.load(open(filepath))
+    patch(result) # add functions to object
+
+    # action update/delete/read
+    if action == ACTION_UPDATE:
+        if VERBOSE:
+            print(f'INFO: Modifying {key} in {filepath}, setting "{value}"\n')
+        result.write_key(key, value)
+    elif action == ACTION_DELETE:
+        if VERBOSE:
+            print(f'INFO: Deleting {key} from {filepath}\n')
+        result.delete_key(key)
+    elif action == ACTION_READ:
+        if VERBOSE:
+            print(f'INFO: Reading {key} from {filepath}')
+        print(result.get_key(key))
+        sys.exit(0)
+
+    # output
+    if inplace_write:
+        yaml.dump(result, open(filepath, 'w'))
+    else:
+        print('OUTPUT:')
+        yaml.dump(result, sys.stdout)

2020_07_15_51st/lightningtalks/yaml-parsing/example.py

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+#!/usr/bin/env python3
+import sys
+from ruamel.yaml import YAML
+
+# for more see: https://yaml.readthedocs.io/en/latest/
+
+# read
+yaml = YAML() # uses roundtrip (keeps comments and order)
+# yaml = YAML(typ='safe') # alternative, does not keep comments and order
+result = yaml.load(open('[path_to_your_file]'))
+
+# modify
+print(result['db']['password']) # read value
+result['db']['password'] = 'MY_NEW_SECRET' # create/update value
+del result['deprecated']['key'] # delete key
+
+# output
+yaml.dump(result, sys.stdout) # write to stdout
+yaml.dump(result, open('[path_to_your_file]', 'w')) # write to file inplace

2020_07_15_51st/lightningtalks/yaml-parsing/examples/example-test.yml

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+# MY ANSIBLE VAULT SECRET FILE
+
+# mysql credentials
+db:
+    user: TEST_USER
+    password: KEEP_THIS_SECRET
+
+# access to rest api
+rest_api:
+    access_token: PLACE_TOKEN_HERE
+
+deprectated:
+  key: REMOVE_THIS

2020_07_15_51st/lightningtalks/yaml-parsing/presentation.md

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+# Automating YAML parsing / editing
+whoami: Billy Duong
+
+
+## Why?
+Why automate?
+
+- YAML is not machine parser friendly (e.g. regex)
+- I needed to manage multiple files 'semi-regularly'
+- Ex. ansible vault file, docker files, kubernetes, ...
+
+
+## What?
+What do I need?
+
+- Required: Read, edit, delete values
+- Required: Keep file structure!!
+- Required: Keep comments in file!!
+- Required: Additional scripting
+- Optional: Edit values based on keys (my.long.key)
+
+
+## How?
+How did I solve it?
+
+- Python 3 (personal preference)
+- ruamel.yaml (based on PyYAML)
+
+
+## Sources
+More information:
+- https://yaml.readthedocs.io/en/latest/
+- https://yaml.org/
+- https://en.wikipedia.org/wiki/YAML
+
+YAML usage examples:
+- https://docs.ansible.com/ansible/latest/user_guide/vault.html
+- https://docs.docker.com/compose/