Session Files

The first parameter you pass to the constructor of the TelegramClient is the session, and defaults to be the session name (or full path). That is, if you create a TelegramClient('anon') instance and connect, an anon.session file will be created on the working directory.

These database files using sqlite3 contain the required information to talk to the Telegram servers, such as to which IP the client should connect, port, authorization key so that messages can be encrypted, and so on.

These files will by default also save all the input entities that you’ve seen, so that you can get information about an user or channel by just their ID. Telegram will not send their access_hash required to retrieve more information about them, if it thinks you have already seem them. For this reason, the library needs to store this information offline.

The library will by default too save all the entities (chats and channels with their name and username, and users with the phone too) in the session file, so that you can quickly access them by username or phone number.

If you’re not going to work with updates, or don’t need to cache the access_hash associated with the entities’ ID, you can disable this by setting client.session.save_entities = False.

Custom Session Storage

If you don’t want to use the default SQLite session storage, you can also use one of the other implementations or implement your own storage.

To use a custom session storage, simply pass the custom session instance to TelegramClient instead of the session name.

Telethon contains two implementations of the abstract Session class:

  • MemorySession: stores session data in Python variables.
  • SQLiteSession, (default): stores sessions in their own SQLite databases.

There are other community-maintained implementations available:

  • SQLAlchemy: stores all sessions in a single database via SQLAlchemy.
  • Redis: stores all sessions in a single Redis data store.

Creating your own storage

The easiest way to create your own storage implementation is to use MemorySession as the base and check out how SQLiteSession or one of the community-maintained implementations work. You can find the relevant Python files under the sessions directory in Telethon.

After you have made your own implementation, you can add it to the community-maintained session implementation list above with a pull request.

SQLite Sessions and Heroku

You probably have a newer version of SQLite installed (>= 3.8.2). Heroku uses SQLite 3.7.9 which does not support WITHOUT ROWID. So, if you generated your session file on a system with SQLite >= 3.8.2 your session file will not work on Heroku’s platform and will throw a corrupted schema error.

There are multiple ways to solve this, the easiest of which is generating a session file on your Heroku dyno itself. The most complicated is creating a custom buildpack to install SQLite >= 3.8.2.

Generating a SQLite Session File on a Heroku Dyno

Note

Due to Heroku’s ephemeral filesystem all dynamically generated files not part of your applications buildpack or codebase are destroyed upon each restart.

Warning

Do not restart your application Dyno at any point prior to retrieving your session file. Constantly creating new session files from Telegram’s API will result in a 24 hour rate limit ban.

Due to Heroku’s ephemeral filesystem all dynamically generated files not part of your applications buildpack or codebase are destroyed upon each restart.

Using this scaffolded code we can start the authentication process:

client = TelegramClient('login.session', api_id, api_hash).start()

At this point your Dyno will crash because you cannot access stdin. Open your Dyno’s control panel on the Heroku website and “Run console” from the “More” dropdown at the top right. Enter bash and wait for it to load.

You will automatically be placed into your applications working directory. So run your application python app.py and now you can complete the input requests such as “what is your phone number” etc.

Once you’re successfully authenticated exit your application script with CTRL + C and ls to confirm login.session exists in your current directory. Now you can create a git repo on your account and commit login.session to that repo.

You cannot ssh into your Dyno instance because it has crashed, so unless you programatically upload this file to a server host this is the only way to get it off of your Dyno.

You now have a session file compatible with SQLite <= 3.8.2. Now you can programatically fetch this file from an external host (Firebase, S3 etc.) and login to your session using the following scaffolded code:

fileName, headers = urllib.request.urlretrieve(file_url, 'login.session')
client = TelegramClient(os.path.abspath(fileName), api_id, api_hash).start()

Note

  • urlretrieve will be depreciated, consider using requests.
  • file_url represents the location of your file.