I am working on a Django project where I use a cron job to manage Spotify playlists using the Spotify API. The cron job is scheduled with django-crontab and is intended to add tracks to multiple Spotify playlists across different accounts.

Problem:
The cron job works fine up to a certain point, but I encounter the following error repeatedly:

ERROR 2024-09-06 01:11:02,768 cron Error adding tracks: [Errno 98] Address already in use
ERROR 2024-09-06 01:11:07,771 cron Error adding tracks: [Errno 98] Address already in use
ERROR 2024-09-06 01:11:12,774 cron Error adding tracks: [Errno 98] Address already in use

What I have tried:

• Environment: I am using Ubuntu with Django, django-crontab, and Spotipy (a Python client for the Spotify Web API).
• Spotify Web API Sandbox: I tested the API with spotify web API and it works fine there.
• Error Analysis: The error occurs after a log statement indicating that a user ID is being used to add tracks to a playlist. The next try block does not execute, and the [Errno 98] Address already in use error is raised.
• Port Conflict Check: I initially thought the error might be due to port conflicts with the Django server running on port 8000, but I understand that my Django server is expected to run on this port, so checking for its usage is not necessary.
• Error Handling and Retrying: I’ve implemented retry logic to handle exceptions such as Spotify API rate limits (429 Too Many Requests) and permission errors (403 Forbidden). The retry logic handles these exceptions correctly, but the [Errno 98] Address already in use error persists.

def add_tracks_to_playlist(order, playlist_id, track_uris, sp, spotify_account):
    retries = 3
    delay = 5
    USER_ID = spotify_account.spotify_key.username

    logger.info(f"Using user ID {USER_ID} to add tracks to playlist {playlist_id}")

    for attempt in range(retries):
        try:
            logger.debug(f"Attempting to add {len(track_uris)} tracks to playlist {playlist_id}, attempt {attempt + 1}")
            sp.user_playlist_add_tracks(USER_ID, playlist_id, track_uris)
            logger.info(f"Successfully added {len(track_uris)} tracks to playlist {playlist_id} for user {order.user_id}")

            update_order_status(order)
            break  # Exit the loop if successful

        except SpotifyException as e:
            logger.error(f"Spotify API error: {e.msg}")
            logger.debug(f"Spotify API response: {e}")

            if e.http_status == 403:
                logger.error(f"Check if the user {USER_ID} is correctly registered and has permissions to modify the playlist.")
                return  # Exit further retries as this is likely a permissions issue

            if e.http_status == 429:  # Rate limit exceeded
                retry_after = int(e.headers.get('Retry-After', delay))
                logger.info(f"Rate limit exceeded. Retrying after {retry_after} seconds.")
                time.sleep(retry_after)

        except OSError as e:
            if e.errno == 98:  # Address already in use
                logger.error(f"Error adding tracks: Address already in use. Retrying after {delay} seconds.")
                time.sleep(delay)
            else:
                logger.error(f"OS Error: {e}")
                logger.debug(f"Detailed OS exception: {repr(e)}")
                time.sleep(delay)

        except Exception as e:
            logger.error(f"Error adding tracks: {e}")
            logger.debug(f"Detailed exception: {repr(e)}")
            time.sleep(delay)

    else:
        logger.error(f"Failed to add tracks to playlist {playlist_id} after {retries} attempts.")

Cronjob log

INFO 2024-09-06 15:29:01,639 cron Cron started
INFO 2024-09-06 15:29:01,640 cron Cron job started.
INFO 2024-09-06 15:29:01,644 cron 1 pending orders found.
INFO 2024-09-06 15:29:01,646 cron Processing Order ID 35 with 1 playlists.
INFO 2024-09-06 15:29:01,653 cron Initializing Spotify client for user myuserid with Client ID: myclientid
INFO 2024-09-06 15:29:01,654 cron Successfully initialized SpotifyOAuth for user.
INFO 2024-09-06 15:29:01,654 cron Assigned jobs: [1]
INFO 2024-09-06 15:29:01,655 cron Distributing 1 playlists to job scheduled at 2024-09-06 15:38:01.655010 for Order ID 35.
INFO 2024-09-06 15:29:01,655 cron Adding track 4jYwFHigUt3c21ATMklTku to playlist 4ZwEDixe0VTBSCHfLLqKoH
ERROR 2024-09-06 15:29:01,659 cron Error adding tracks: [Errno 98] Address already in use
ERROR 2024-09-06 15:29:06,662 cron Error adding tracks: [Errno 98] Address already in use
ERROR 2024-09-06 15:29:11,668 cron Error adding tracks: [Errno 98] Address already in use

According to the log cronjob works fine till this line of code logger.info(f"Using user ID {USER_ID} to add tracks to playlist {playlist_id}") but when it tries to add song into spotify playlist using spotipy function sp.user_playlist_add_tracks(USER_ID, playlist_id, track_uris) it gives me OS Error 98

Additional Information:

sudo lsof -i -n -P | grep LISTEN

systemd-r   605 systemd-resolve   14u  IPv4  18718      0t0  TCP 127.0.0.53:53 (LISTEN)
cupsd       916            root    6u  IPv6  21045      0t0  TCP [::1]:631 (LISTEN)
cupsd       916            root    7u  IPv4  21046      0t0  TCP 127.0.0.1:631 (LISTEN)
postman-a 13327       a-h-m-a-r   71u  IPv4 111201      0t0  TCP 127.0.0.1:10533 (LISTEN)
python    25924       a-h-m-a-r    8u  IPv4 224162      0t0  TCP 127.0.0.1:8000 (LISTEN)

• The error occurs intermittently and seems to be related to network or socket handling.
• The cron job is designed to run at specific intervals, and I have a cache-based lock to ensure only one instance runs at a time.

My Setup:

• Django Version: latest
• Python Version: 3.12
• Spotipy for adding songs to playlist
• OS: Ubuntu 20.04
• Tools: django-crontab for scheduling the cron job

Question:

• What could be causing the [Errno 98] Address already in use error within the context of my cron job?
• How can I modify my code or cron job setup to avoid this error while ensuring reliable execution of my task?
• Are there best practices or alternative approaches for handling such network-related errors in a cron job environment in Django?

Wget Request Sample:

wget --quiet 
  --method POST 
  --header 'Content-Type: application/json' 
  --header 'Authorization: Bearer 1POdFZRZbvb...qqillRxMr2z' 
  --body-data '{n    "uris": [n        "3yHyiUDJdz02FZ6jfUbsmY"n    ],n    "position": 0n}' 
  --output-document 
  - 'https://api.spotify.com/v1/playlists/4ZwEDixe0VTBSCHfLLqKoH/tracks?uris=spotify%3Atrack%3A3yHyiUDJdz02FZ6jfUbsmY'

Crontab setup in settings.py

CRONJOBS = [
    ('*/5 * * * *', 'app.cronjob.cron.my_scheduled_job'),
]
CRONTAB_LOCK_JOBS = True