At startup, the bot calls getMe and prints its bot information and supportsJoinRequestQueries value. For every chat join request it prints the requesting user, chat, bio, query ID, and the chat's configured guard bot.

Only requests containing a query ID are processed. Without a Web App URL, the bot:

answers with Queue when the user's bio is missing or blank, leaving the decision to other administrators;
answers with Approve when the user has a nonblank bio.

When an HTTPS Web App URL is supplied, the bot sends that Web App for verification instead of answering the query. Requests without a query ID are only logged. Every received update is printed to standard output, and the bot defines no commands.

Setup and permissions

Create a bot, obtain its token, and keep the token private.
Configure the bot as the guard bot of the chat whose requests it should handle.
Grant it the administrator permission to invite users (can_invite_users).
If using the Web App flow, provide an HTTPS verification URL.

The example uses long polling and does not configure a webhook. Be aware that its default flow automatically approves query-backed requests with a nonblank bio.

Run

From the repository root:

./gradlew :JoinRequestQueriesBot:run --args="BOT_TOKEN"

The first argument is the required bot token. An optional Web App URL is recognized only as the second argument and must begin with https://. The case-sensitive flags debug and testServer enable formatted logging and Telegram's test environment; they may follow the token and Web App URL.

For example:

./gradlew :JoinRequestQueriesBot:run --args="BOT_TOKEN https://example.com/verify debug"