Python: Intermediate Snippets

4 minute read

Description:

Here are some snippets I have been using lately:

To Resolve:

  1. To send a REST API call (Event Grid in this Example):

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    from datetime import datetime, timezone
    import requests
    import json
    import collections
    
    def send_req(subject, payload, key):
    
       date1 = datetime.now(timezone.utc)
       date2 = (str(date1).replace(" ", "T").replace("+00:00", "0")) + 'Z'
    
       # generate body
       body = collections.OrderedDict()
       body["body"] = payload
    
       # insert into main body
       data = collections.OrderedDict()
       data["id"] = "MyApp"
       data["subject"] = subject
       data["topic"] = "somePub"
       data["eventType"] = "MyAppApproval"
       data["eventTime"] = date2
       data["data"] = body
       data["dataVersion"] = "1.0"
       data["metadataVersion"] = None
       #print("data: ", data)
    
       headers = collections.OrderedDict()
       headers['Content-Type'] = 'application/json'
       headers['aeg-sas-key'] = key
       #print("headers: ", headers)
    
       data2 = "[" + json.dumps(data) + "]"
       #print("data string: ", data2)
    
       url = "https://mycompany.southcentralus-1.eventgrid.azure.net/api/events"
       r = requests.post(url, headers=headers, data=data2)
       # print(r.status_code)
       return r
    
    
    s = '85d89569-5c9e-4fc6-a394-7bb9d724b614'
    p = '{"AppName": "SomeApp", "PermName": "SomePermission", "ChangeRequestType": "ADD"}'
    k = 'SbBjasdfasdf'
    req = send_req(s, p, k)
    print(req.status_code)
    
    if req.status_code == 200:
       print("good")
    else:
          pass
    
    
  2. To send an email using Office 365 user:

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    import smtplib
    from email.mime.text import MIMEText
    import os
    
    def send_email(strPassword):
          
       html = """\
       <html>
       <head>
       </head>
       <body>
       This is a sample body
       </body>
       </html>
       """
       msg = MIMEText(html, 'html')
       msg['Subject'] = 'Test message'
    
       mailserver = smtplib.SMTP('smtp.office365.com',587)
       mailserver.ehlo()
       mailserver.starttls()
       mailserver.login('fromAccount@domain.com', strPassword)
       mailserver.sendmail('fromAccount@domain.com','toAccount@domain.com',msg.as_string())
       mailserver.quit()
    
    
    try:
       email = os.environ["EMAIL"]
    except Exception as e:
       exit(1)
    
    send_email(email)
    
  3. Read from a CSV file:

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    import csv
    
    def read_csv(filename):
       add_remove = []
       app_name = []
       perm_name = []
    
       with open(filename) as csvDataFile:
          csvReader = csv.reader(csvDataFile)
          for row in csvReader:
                add_remove.append(row[1])
                app_name.append(row[5])
                perm_name.append(row[7])
       return add_remove, app_name, perm_name
    
    file = '/csv/dataset_500.csv'
    add_remove, app_name, perm_name = read_csv(file)
    print(add_remove[1])
    print(app_name[1])
    print(perm_name[1])
    
  4. Loop through files in a directory and move them if needed:

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    import os
    import shutil
    
    directory = '/myapp'
    
    try:
       items = os.scandir(directory)
    except Exception as e:
       print("No files in the directory")
       exit(0)
    
    match = 0
    
    for item in items:
       # print('processing :', item.name)
       if item.path.endswith(".csv") and item.is_file() and item.name.find('dataset') == 0:
          match = match + 1
          print('Found file to process: ', item.path)
          dest = '/myapp/processed/' + item.name
          # do something with the file
          # move file to destination
          try:
                shutil.move(item.path, dest)
          except Exception as e:
                print("Unable to move folder to destination: ", item.name)
       else:
          pass
          
       if match == 0:
          print("No files in the directory that match expected format")
          exit(0)
       else:
          pass
    
    
  5. Run native commands:

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    import subprocess
    
    stat = 'systemctl status firewalld'
    print('Running: ', stat)
    st = subprocess.run(stat, shell=True, stdout=subprocess.PIPE)
    print(st)
    
  6. Using environmental vars:

    • Step 1: Create your venv folder and add the python-dotenv package:
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    cd /myuser/scripts
    mkdir csv
    cd csv
    scl enable rh-python36 bash
    python -m venv /myuser/scripts/csv/venv
    source /myuser/scripts/csv/venv/bin/activate
    pip install --upgrade pip
    python3 -m pip install python-dotenv
    
    • Step 2: Create an .env file at the root of your csv folder and enter
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    EMAIL="somePass"
    KEY="someKey"
    
    • Step 3: Enter the following in your .py file that should also be at root of csv folder
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    from dotenv import load_dotenv
    
    load_dotenv()
    
    try:
       key = os.environ["KEY"]
    except Exception as e:
       print("Unable to get environmental variable: key")
       exit(1)
    # same for EMAIL
    
  7. Implement a base logging:

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    import logging
    import logging.handlers
    import sys
    
    logger = logging.getLogger("")
    logger.setLevel(logging.DEBUG)
    handler = logging.handlers.RotatingFileHandler(
       '/mnt/z/google/scripts/python/example3.log', maxBytes=(1048576*5), backupCount=7
    )
    formatter = logging.Formatter("%(asctime)s => %(levelname)s : %(message)s", datefmt='%Y-%m-%d %I:%M:%S %p')
    handler.setFormatter(formatter)
    logger.addHandler(handler)
    
    logging.getLogger().addHandler(logging.StreamHandler(sys.stdout))
    
    logging.info('hello world')
    
    logging.error('error - hello world')
    
    logging.warning('warning - hello world')
    name = 'Gerry'
    
    logging.error('%s raised an error', name)
    
    a = 5
    b = 0
    
    try:
       c = a / b
    except Exception as e:
       logging.error("Exception occurred", exc_info=True)
    
       logging.warning('warning - hello world')
    
    • Output:
  [user@server logs]# cat eventgrid_2020-06-22-17-19-37.log
   2020-06-22 05:19:37 PM => INFO : ==========================
   2020-06-22 05:19:37 PM => INFO : Starting function...
   2020-06-22 05:19:37 PM => INFO : Logfile fullname: /myuser/scripts/logs/send-eventgrid_2020-06-22-17-19-37.log
   2020-06-22 05:19:37 PM => INFO : Found file to process: /csv/dataset_556.csv
   2020-06-22 05:19:37 PM => INFO : Payload to send: {"key": "someData", "key2": "someData2", "key3": "someData3"}
   2020-06-22 05:19:37 PM => INFO : Sending: SomeData
   2020-06-22 05:19:37 PM => DEBUG : Starting new HTTPS connection (1): mycompany.southcentralus-1.eventgrid.azure.net:443
   2020-06-22 05:19:37 PM => DEBUG : https://mycompany.southcentralus-1.eventgrid.azure.net:443 "POST /api/events HTTP/1.1" 200 0
   2020-06-22 05:19:39 PM => INFO : Request completed successfully

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