Develop Reference

How to fix aws lambda function logs error?

I'm trying to extract aws trust advisor data through lambda function(trigger by event scheduler) and upload to s3. However, some part of the function throws error. below is my code
##libraries
import boto3
import os
import csv
from csv import DictWriter
import time
import traceback
## bucket_name is set as env variable
bucket_name = "test-ta-reports"
fail_msg = 'Pulling Trusted Advisor data failed'
Filename = "/tmp/checks_list.csv"
obj_name = time.strftime("%Y-%m-%d-%H-%M-%S") + '/' + '.csv'
##upload to s3
def s3_upload(bucket_name, Filename, obj_name):
if obj_name is None:
obj_name = os.path.basename(Filename)
try:
s3 = boto3.client("s3", region_name="eu-west-1")
response = s3.upload_file(Filename, bucket_name, obj_name)
return True
except:
print('Data failed to upload to bucket')
traceback.print_exc()
return False
def lambda_handler(event, context):
try:
support_client = boto3.client('support', region_name='us-east-1')
ta_checks = support_client.describe_trusted_advisor_checks(language='en')
checks_list = {ctgs: [] for ctgs in list(set([checks['category'] for checks in ta_checks['checks']]))}
for checks in ta_checks['checks']:
print('Getting check:' + checks['name'] + checks['category'])
try:
check_summary = support_client.describe_trusted_advisor_check_summaries(
checkIds=[checks['id']])['summaries'][0]
if check_summary['status'] != 'not_available':
checks_list[checks['category']].append(
[checks['name'], check_summary['status'],
str(check_summary['resourcesSummary']['resourcesProcessed']),
str(check_summary['resourcesSummary']['resourcesFlagged']),
str(check_summary['resourcesSummary']['resourcesSuppressed']),
str(check_summary['resourcesSummary']['resourcesIgnored'])
])
else:
print("unable to append checks")
except:
print('Failed to get check: ' + checks['name'])
traceback.print_exc()
except:
print('Failed! Debug further.')
traceback.print_exc()
##rewrite dict to csv
with open('/tmp/checks_list.csv', 'w', newline='') as csvfile:
csv_writer = DictWriter(csvfile, fieldnames=['status','hasFlaggedResources','timestamp','resourcesSummary','categorySpecificSummary', 'checkId'])
csv_writer.writeheader()
csv_writer.writerow(check_summary)
return checks_list
if s3_upload(bucket_name, Filename, obj_name):
print("Successfully uploaded")
if __name__ == '__main__':
lambda_handler(event, context)
The error logs
unable to append checks
I'm new to Python. So, unsure of how to check for trackback stacks under else: statement. Is there any way to modify this code for getting traceback logs for the append block. Also, have i made any error in the above code. I'm unable to figure out any. PLz help

response = client.describe_trusted_advisor_check_summaries(
checkIds=[
'string',
]
)
describe_trusted_advisor_check_summaries() returns summarized results for one or more Trusted advisors. Here you are checking for the check_summary['status'] is not equal to not_avaialble i.e. alert status of the check is either "ok" (green), "warning" (yellow), "error" (red), and in that case, you are appending resourcesProcessed, resourcesFlagged, resourcesSuppressed, and resourcesIgnored to checks_list for further processing.
it's printing
unable to append checks
just because the status of the check is not_available. It is not an error log. Just deal with the case if the check status is not_available, what you should be doing?
See the documentation of describe_trusted_advisor_check_summaries. https://boto3.amazonaws.com/v1/documentation/api/latest/reference/services/support.html#Support.Client.describe_trusted_advisor_check_summaries

FileNotFoundError even though Absolute Path Specified

I am running a simple python webserver [SimpleHTTPServer] in my Linux . Wrote a python program to download all the files hosted in that server to my Windows Machine . But for some reason program is throwing FileNotFoundError even though Directory exists and I've provided Absolute Path .
Here is the code : https://drive.google.com/file/d/1CDrueDJcbu2z1XeeB_iYv0zmfIX1cCkx/view?usp=sharing
It's working correctly in Linux but trouble with Windows . Thanks
import requests
import argparse
from sys import argv
from urllib.parse import unquote
import os
from time import time
import random
from colorama import Fore, Style
import platform
def formatFiles(name):
name = name[13:-9]
nameLen = len(name) - 2
nameLen = int(nameLen/2)
name = name[:nameLen]
return name
# Creating a Temporary Folder to Download all the files in it
def fileCreate(saveFolder):
random.seed(int(time()))
text = ""
for x in range(5):
y = random.randrange(65,91)
text += chr(y)
saveFolder += text
os.popen("mkdir {}".format(saveFolder))
print("Temp Directory {} created to save files/folders".format(text))
return saveFolder
def winDows(endPoint, banner):
resp = requests.get(endPoint, allow_redirects=True)
resp = resp.text.split("\n")
resp = list(map(unquote, resp[10:-5])) #URL decoding using unquote
resp = list(map(formatFiles,resp))
for dir in resp:
tempPath = ""
tempEndpoint = endPoint[len(serverURL):] # Getting directory structure by removing IP:PORT in URL
tempPath = "\\".join(tempEndpoint.split("/")) # Removing / and adding \\ for Windows path
print(banner + dir)
tdir = dir
if(dir[-1] == "/"):
if( dir.split(" ")!=1 ): # If the directory name has spaces ,
tdir = dir[:-1]
tdir = "\""+tdir+"\""+"\\"
os.popen("mkdir "+saveFolder+"\\"+tempPath+tdir)
r = winDows(endPoint+dir, banner[:-4]+" |___")
else:
data = open(saveFolder+"\\"+tempPath+dir, "wb")
fileData = requests.get(endPoint+dir, allow_redirects=True)
data.write(fileData.content)
data.close()
return 1
parser = argparse.ArgumentParser()
sideBanner = " |___ "
parser.add_argument("ip", help = "IP address of FTP Server", type=ip_valid)
parser.add_argument("port" , help = "FTP Server Port you want to access", type=port_valid)
parser.add_argument("dst", help="Destination Path to save your files")
args = parser.parse_args()
ip = argv[1]
port = argv[2]
saveFolder = argv[3]
serverURL = "http://"+ip+":"+port+"/"
saveFolder = fileCreate(saveFolder)
print("Destination Folder - {}".format(saveFolder))
if(platform.system() == "Linux"):
linuX(serverURL, sideBanner)
else:
winDows(serverURL, sideBanner)

Python - Problem use loops to get day by day

I'm trying to make a google api downloader that will bypass api restrictions.
Unfortunately, what I do does not work. As I do not introduce loops, unfortunately the change of dates by hand works when downloading historical data is very easy. For new data, no problem skypt generates data daily.
Below is the code at which I try to download data from a specific range day by day.
The problem occurs in this part of the code
def get_top_keywords(service, profile_id):
for day_number in range(total_days):
return service.data().ga().get(
ids='ga:' + profile_id,
start_date='1daysAgo',
end_date=(start_date + dt.timedelta(days = day_number)).date(),
metrics='ga:sessions, ga:newUsers, ga:users, ga:organicSearches, ga:pageviews, ga:bounceRate',
dimensions='ga:date, ga:source, ga:medium',
max_results='10000').execute()
Below the whole code
import argparse
import sys
reload(sys)
sys.setdefaultencoding('utf-8')
import csv
from __future__ import print_function
from googleapiclient.errors import HttpError
from googleapiclient import sample_tools
from oauth2client.client import AccessTokenRefreshError
import datetime as dt
start_date = dt.datetime(2019, 01,1)
end_date = dt.datetime(2019, 01,5)
total_days = (end_date - start_date).days + 1
def main(argv):
# Authenticate and construct service.
service, flags = sample_tools.init(
argv, 'analytics', 'v3', __doc__, __file__,
scope='https://www.googleapis.com/auth/analytics.readonly')
# Try to make a request to the API. Print the results or handle errors.
try:
first_profile_id = '11111111111' # Hard Code View Profile ID Here
if not first_profile_id:
print('Could not find a valid profile for this user.')
else:
results = get_top_keywords(service, first_profile_id)
print_results(results)
except TypeError as error:
# Handle errors in constructing a query.
print(('There was an error in constructing your query : %s' % error))
except HttpError as error:
# Handle API errors.
print(('Arg, there was an API error : %s : %s' %
(error.resp.status, error._get_reason())))
except AccessTokenRefreshError:
# Handle Auth errors.
print ('The credentials have been revoked or expired, please re-run '
'the application to re-authorize')
def get_first_profile_id(service):
accounts = service.management().accounts().list().execute()
if accounts.get('items'):
firstAccountId = accounts.get('items')[0].get('id')
webproperties = service.management().webproperties().list(
accountId=firstAccountId).execute()
if webproperties.get('items'):
firstWebpropertyId = webproperties.get('items')[0].get('id')
profiles = service.management().profiles().list(
accountId=firstAccountId,
webPropertyId=firstWebpropertyId).execute()
if profiles.get('items'):
return profiles.get('items')[0].get('id')
return None
def get_top_keywords(service, profile_id):
for day_number in range(total_days):
return service.data().ga().get(
ids='ga:' + profile_id,
start_date='1daysAgo',
end_date=(start_date + dt.timedelta(days = day_number)).date(),
metrics='ga:sessions, ga:newUsers, ga:users, ga:organicSearches, ga:pageviews, ga:bounceRate',
dimensions='ga:date, ga:source, ga:medium',
max_results='10000').execute()
def print_results(results):
print()
print('Profile Name: %s' % results.get('profileInfo').get('profileName'))
print()
# Open a file.
filepath = '/temp/' #change this to your actual file path
filename = 'temp.csv' #change this to your actual file name
f = open(filepath + filename, 'wt')
# Wrap file with a csv.writer
writer = csv.writer(f, lineterminator='\n')
# Write header.
header = [h['name'][3:] for h in results.get('columnHeaders')] #this takes the column headers and gets rid of ga: prefix
writer.writerow(header)
print(''.join('%30s' %h for h in header))
# Write data table.
if results.get('rows', []):
for row in results.get('rows'):
writer.writerow(row)
print(''.join('%30s' %r for r in row))
print('\n')
print ('Success Data Written to CSV File')
print ('filepath = ' + filepath)
print ('filename = '+ filename)
else:
print ('No Rows Found')
# Close the file.
f.close()
if __name__ == '__main__':
main(sys.argv)
What should I improve to make the date automatically reach the end of the loop?
Why the loop doesn't work, I'm just starting with python but I'm trying

Yes, I added a loop, I just did something wrong, because when I test the loop itself, it works, but when I apply it to the code connecting to api, it doesn't work anymore
for day_number in range(total_days):
return service.data().ga().get(
ids='ga:' + profile_id,
start_date='1daysAgo',
end_date=(start_date + dt.timedelta(days = day_number)).date(),
metrics='ga:sessions, ga:newUsers, ga:users, ga:organicSearches, ga:pageviews, ga:bounceRate',
dimensions='ga:date, ga:source, ga:medium',
max_results='10000').execute()

How to download data into uncreated file directory in Python?

#This is my webpage_getinfo.py script used to parse emails, phone numbers and other details from a webpage. It will be needed for the file_download.py script#
import sys, re
import webpage_get
def print_md5s(page):
print '[*] print_md5s()'
md5s = re.findall(r'([a-fA-F\d]{32})', page)
md5s.sort()
print '[+]', str(len(md5s)), 'MD5 Hashes Found:'
for md5 in md5s:
print md5
def print_emails(page):
print '[*] print_emails()'
emails = re.findall(r'[\w\-][\w\-\.]+#[\w\-][\w\-\.]+[a-zA-Z]{1,4}', page)
emails.sort()
print '[+]', str(len(emails)), 'Email Addresses Found:'
for email in emails:
print email
def print_phones(page):
print '[*] print_phones numbers()'
phones = re.findall(r'\+\d................', page)
phones.sort()
print '[+]', str(len(phones)), 'Phone Numbers Found:'
for phone in phones:
print phone
def print_images(page):
print '[*] print_images()'
images = re.findall(r'\w+.\jpg|\w+.\gif|\w+.\w+\.\wmp', page)
images.sort()
print '[+]', str(len(images)), 'Images Found:'
for image in images:
print image
def print_documents(page):
print '[*] print_documents()'
documents = re.findall(r'\w+\.\wocx', page)
documents.sort()
print '[+]', str(len(documents)), 'Documents Found:'
for document in documents:
print document
def main():
page = webpage_get.webget(sys.argv) # getting the webpage from webpage_get.py as 'page'
print_md5s(page)
print_emails(page)
print_phones(page)
print_images(page)
print_documents(page)
if __name__ == '__main__':
main()
## This is the code for file_download.py below. It download the details from webpage_getinfo and stores it in an uncreated file directory, creating the directory as soon as the script is run##
import errno
import sys, os, urllib2, urllib
import webpage_getinfo
page = 'http://www.soc.napier.ac.uk/~cs342/CSN08115/cw_webpage/index.html'
def path_to_download():
file_name = 'file.txt' # creates the file name
script_dir = os.path.dirname(os.path.abspath(file_name))
dest_dir = os.path.join(script_dir, 'C:\\temp', 'coursework')
try:
os.makedirs(dest_dir)
except IOError:
print 'Warning: file already exists'
path = os.path.join(dest_dir, file_name)
# writing the details of each information from webpage_getinfo
file_dest = open(dest_dir, 'w') # opening the destination directory
file_dest.write('Here is the site documents\n')
file_dest.write(md5details)
file_dest.write(emails)
file_dest.write(phones)
file_dest.write(images)
file_dest.write(documents)
def main():
path_to_download()
md5_info = webpage_getinfo.print_md5s() # getting md5 from webpage_getinfo.py
email_info = webpage_getinfo.print_emails() # getting emails from webpage_getinfo.py
phones_info = webpage_getinfo.print_phones() # getting phone numbers from webpage_getinfo.py
images_info = webpage_getinfo.print_images() # getting images from webpage_getinfo.py
documents_info = webpage_getinfo.print_documents() # getting documents from webpage_getinfo.py
if __name__ == '__main__':
main()
# Anytime I run the script, it tells me 'IOError: Permission denied' if the file doesn't exist. Please, any code correction and assistance through advice would be appreciated. I'm an amateur in python, so excuse my messy codes.Thanks.#

Only make the path if it's not already there, like this:
if not os.path.exists(dest_dir):
os.makedirs(dest_dir)

Automatic background changer using Python 2.7.3 not working, though it should

I'm very new to Ubuntu/Python/Bash/Gnome in general, so I still feel like there's a chance I'm doing something wrong, but it's been 3 days now without success...
Here's what the script is supposed to do:
* [✓] Download 1 random image from wallbase.cc
* [✓] Save it to the same directory that the script is running from
* [x] Set it as the wallpaper
There are two attempts made to set the wallpaper two using different commands and NEITHER work when in the script. There is a print statement (2nd line from the bottom) that spits out the correct terminal command because I can C&P the print result and it works fine, it just doesn't work when it's executed in the script.
#!/usr/bin/env python
import urllib2
import os
from gi.repository import Gio
response = urllib2.urlopen("http://wallbase.cc/random/12/eqeq/1366x768/0.000/100/32")
page_source = response.read()
thlink_pos = page_source.find("ico-X")
address_start = (page_source.find("href=\"", thlink_pos) + 6)
address_end = page_source.find("\"", address_start + 1)
response = urllib2.urlopen(page_source[address_start:address_end])
page_source = response.read()
bigwall_pos = page_source.find("bigwall")
address_start = (page_source.find("src=\"", bigwall_pos) + 5)
address_end = page_source.find("\"", address_start + 1)
address = page_source[address_start:address_end]
slash_pos = address.rfind("/") + 1
pic_name = address[slash_pos:]
bashCommand = "wget " + page_source[address_start:address_end]
os.system(bashCommand)
print "Does my new image exists?", os.path.exists(os.getcwd() + "/" + pic_name)
#attempt 1
settings = Gio.Settings.new("org.gnome.desktop.background")
settings.set_string("picture-uri", "file://" + os.getcwd() + "/" + pic_name)
settings.apply()
#attempt 2
bashCommand = "gsettings set org.gnome.desktop.background picture-uri file://" + os.getcwd() + "/" + pic_name
print bashCommand
os.system(bashCommand)
settings.apply()

You've successfully changed your settings, but they're still left unapplied, try next:
settings.apply()
after setting "picture-uri" string.

It works for me (Ubuntu 12.04).
I've modified your script (unrelated to your error):
#!/usr/bin/python
"""Set desktop background using random images from http://wallbase.cc
It uses `gi.repository.Gio.Settings` to set the background.
"""
import functools
import itertools
import logging
import os
import posixpath
import random
import re
import sys
import time
import urllib
import urllib2
import urlparse
from collections import namedtuple
from bs4 import BeautifulSoup # $ sudo apt-get install python-bs4
from gi.repository.Gio import Settings # pylint: disable=F0401,E0611
DEFAULT_IMAGE_DIR = os.path.expanduser('~/Pictures/backgrounds')
HTMLPAGE_SIZE_MAX = 1 << 20 # bytes
TIMEOUT_MIN = 300 # seconds
TIMEOUT_DELTA = 30 # jitter
# "Anime/Manga", "Wallpapers/General", "High Resolution Images"
CATEGORY_W, CATEGORY_WG, CATEGORY_HR = range(1, 4)
PURITY_SFW, PURITY_SKETCHY, PURITY_NSFW, PURITY_DEFAULT = 4, 2, 1, 0
DAY_IN_SECONDS = 86400
UrlRetreiveResult = namedtuple('UrlRetreiveResult', "path headers")
def set_background(image_path, check_exist=True):
"""Change desktop background to image pointed by `image_path`.
"""
if check_exist: # make sure we can read it (at this time)
with open(image_path, 'rb') as f:
f.read(1)
# prepare uri
path = os.path.abspath(image_path)
if isinstance(path, unicode): # quote() doesn't like unicode
path = path.encode('utf-8')
uri = 'file://' + urllib.quote(path)
# change background
bg_setting = Settings.new('org.gnome.desktop.background')
bg_setting.set_string('picture-uri', uri)
bg_setting.apply()
def url2filename(url):
"""Return basename corresponding to url.
>>> url2filename('http://example.com/path/to/file?opt=1')
'file'
"""
urlpath = urlparse.urlsplit(url).path # pylint: disable=E1103
basename = posixpath.basename(urllib.unquote(urlpath))
if os.path.basename(basename) != basename:
raise ValueError # refuse 'dir%5Cbasename.ext' on Windows
return basename
def download(url, dirpath, extensions=True, filename=None):
"""Download url to dirpath.
Use basename of the url path as a filename.
Create destination directory if necessary.
Use `extensions` to require the file to have an extension or any
of in a given sequence of extensions.
Return (path, headers) on success.
Don't retrieve url if path exists (headers are None in this case).
"""
if not os.path.isdir(dirpath):
os.makedirs(dirpath)
logging.info('created directory %s', dirpath)
# get filename from the url
filename = url2filename(url) if filename is None else filename
if os.path.basename(filename) != filename:
logging.critical('filename must not have path separator in it "%s"',
filename)
return
if extensions:
# require the file to have an extension
root, ext = os.path.splitext(filename)
if root and len(ext) > 1:
# require the extension to be in the list
try:
it = iter(extensions)
except TypeError:
pass
else:
if ext not in it:
logging.warn(("file extension is not in the list"
" url=%s"
" extensions=%s"),
url, extensions)
return
else:
logging.warn("file has no extension url=%s", url)
return
# download file
path = os.path.join(dirpath, filename)
logging.info("%s\n%s", url, path)
if os.path.exists(path): # don't retrieve if path exists
logging.info('path exists')
return UrlRetreiveResult(path, None)
try:
return UrlRetreiveResult(*urllib.urlretrieve(url, path,
_print_download_status))
except IOError:
logging.warn('failed to download {url} -> {path}'.format(
url=url, path=path))
def _print_download_status(block_count, block_size, total_size):
logging.debug('%10s bytes of %s', block_count * block_size, total_size)
def min_time_between_calls(min_delay):
"""Enforce minimum time delay between calls."""
def decorator(func):
lastcall = [None] # emulate nonlocal keyword
#functools.wraps(func)
def wrapper(*args, **kwargs):
if lastcall[0] is not None:
delay = time.time() - lastcall[0]
if delay < min_delay:
_sleep(min_delay - delay)
lastcall[0] = time.time()
return func(*args, **kwargs)
return wrapper
return decorator
#min_time_between_calls(5)
def _makesoup(url):
try:
logging.info(vars(url) if isinstance(url, urllib2.Request) else url)
page = urllib2.urlopen(url)
soup = BeautifulSoup(page.read(HTMLPAGE_SIZE_MAX))
return soup
except (IOError, OSError) as e:
logging.warn('failed to return soup for %s, error: %s',
getattr(url, 'get_full_url', lambda: url)(), e)
class WallbaseImages:
"""Given parameters it provides image urls to download."""
def __init__(self,
categories=None, # default; sequence of CATEGORY_*
resolution_exactly=True, # False means 'at least'
resolution=None, # all; (width, height)
aspect_ratios=None, # all; sequence eg, [(5,4),(16,9)]
purity=PURITY_DEFAULT, # combine with |
thumbs_per_page=None, # default; an integer
):
"""See usage below."""
self.categories = categories
self.resolution_exactly = resolution_exactly
self.resolution = resolution
self.aspect_ratios = aspect_ratios
self.purity = purity
self.thumbs_per_page = thumbs_per_page
def _as_request(self):
"""Create a urllib2.Request() using given parameters."""
# make url
if self.categories is not None:
categories = "".join(str(n) for n in (2, 1, 3)
if n in self.categories)
else: # default
categories = "0"
if self.resolution_exactly:
at_least_or_exactly_resolution = "eqeq"
else:
at_least_or_exactly_resolution = "gteq"
if self.resolution is not None:
resolution = "{width:d}x{height:d}".format(
width=self.resolution[0], height=self.resolution[1])
else:
resolution = "0x0"
if self.aspect_ratios is not None:
aspect_ratios = "+".join("%.2f" % (w / float(h),)
for w, h in self.aspect_ratios)
else: # default
aspect_ratios = "0"
purity = "{0:03b}".format(self.purity)
thumbs = 20 if self.thumbs_per_page is None else self.thumbs_per_page
url = ("http://wallbase.cc/random/"
"{categories}/"
"{at_least_or_exactly_resolution}/{resolution}/"
"{aspect_ratios}/"
"{purity}/{thumbs:d}").format(**locals())
logging.info(url)
# make post data
data = urllib.urlencode(dict(query='', board=categories, nsfw=purity,
res=resolution,
res_opt=at_least_or_exactly_resolution,
aspect=aspect_ratios,
thpp=thumbs))
req = urllib2.Request(url, data)
return req
def __iter__(self):
"""Yield background image urls."""
# find links to bigwall pages
# css-like: #thumbs div[class="thumb"] \
# a[class~="thlink" and href^="http://"]
soup = _makesoup(self._as_request())
if not soup:
logging.warn("can't retrieve the main page")
return
thumbs_soup = soup.find(id="thumbs")
for thumb in thumbs_soup.find_all('div', {'class': "thumb"}):
bigwall_a = thumb.find('a', {'class': "thlink",
'href': re.compile(r"^http://")})
if bigwall_a is None:
logging.warn("can't find thlink link")
continue # try the next thumb
# find image url on the bigwall page
# css-like: #bigwall > img[alt and src^="http://"]
bigwall_soup = _makesoup(bigwall_a['href'])
if bigwall_soup is not None:
bigwall = bigwall_soup.find(id='bigwall')
if bigwall is not None:
img = bigwall.find('img',
src=re.compile(r"(?i)^http://.*\.jpg$"),
alt=True)
if img is not None:
url = img['src']
filename = url2filename(url)
if filename.lower().endswith('.jpg'):
yield url, filename # successfully found image url
else:
logging.warn('suspicious url "%s"', url)
continue
logging.warn("can't parse bigwall page")
def main():
level = logging.INFO
if '-d' in sys.argv:
sys.argv.remove('-d')
level = logging.DEBUG
# configure logging
logging.basicConfig(format='%(levelname)s: %(asctime)s %(message)s',
level=level, datefmt='%Y-%m-%d %H:%M:%S %Z')
if len(sys.argv) > 1:
backgrounds_dir = sys.argv[1]
else:
backgrounds_dir = DEFAULT_IMAGE_DIR
# infinite loop: Press Ctrl+C to interrupt it
#NOTE: here's some arbitrary logic: modify for you needs e.g., break
# after the first image found
timeout = TIMEOUT_MIN # seconds
for i in itertools.cycle(xrange(timeout, DAY_IN_SECONDS)):
found = False
try:
for url, filename in WallbaseImages(
categories=[CATEGORY_WG, CATEGORY_HR, CATEGORY_W],
purity=PURITY_SFW,
thumbs_per_page=60):
res = download(url, backgrounds_dir, extensions=('.jpg',),
filename=filename)
if res and res.path:
found = True
set_background(res.path)
# don't hammer the site
timeout = max(TIMEOUT_MIN, i % DAY_IN_SECONDS)
_sleep(random.randint(timeout, timeout + TIMEOUT_DELTA))
except Exception: # pylint: disable=W0703
logging.exception('unexpected error')
_sleep(timeout)
else:
if not found:
logging.error('failed to retrieve any images')
_sleep(timeout)
timeout = (timeout * 2) % DAY_IN_SECONDS
def _sleep(timeout):
"""Add logging to time.sleep() call."""
logging.debug('sleep for %s seconds', timeout)
time.sleep(timeout)
main()

Tried to implement a python script that used the PIL library to write text on an image then update the Gnome background "picture-uri" to point to that image using the Gio class. The python script would ping pong between two images to always modify the one not in use and then attempt to "switch" by updating the Settings. Did this to avoid any flicker as modifying the current background directly drops it out temporarily. While in the shell and calling the script directly I rarely saw any issue, but in the cronjob it simply wouldn't update on the pong. I used both sync and apply and would wait several minutes before trying to switch the images. Didn't work. Tried cron as user (su -c "cmd" user) and that didn't work either.
Finally gave up on the ping pong approach when I noticed that Gnome will detect any change in the background file and update. So dropped the ping pong method and went to a temp file that I just copy over the current background using the shutil library. Works like a charm.