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As of 2021, Discord has significantly enhanced its functionality with the introduction of Discord slash commands. This new feature allows developers to create more interactive and responsive bots by forwarding events directly to specified interaction endpoint. This shift means you are no longer required to listen continuously for message events, leading to more efficient and scalable bot development.

Preview

Embracing Serverless Architecture

With these advancements, it’s now possible to utilize AWS Lambda to perform bot actions, starting lambda function only when a request is received. This method saves computing power and allows for seamless scaling based on demand. A practical demonstration of this concept is available in this proof of concept repository.

New Possibilities with Slash Commands

By using slash commands, developers can implement various functionalities such as:

  • User Verification: Automate user verification based on criteria of your choice.
  • Game Server Initialization: Automatically set up game servers in response to user commands.

Architecture Overview

The simplest view of this architecture can be visualized as follows:

Discord -> API Gateway -> Lambda -> Discord

When a user performs an action, such as /foo bar, the request is directed to your endpoint which you can specify in (Bot Application) > Interactions Endpoint URL for processing which you can declare custom responses.

To handle such requests, you need to set up an API Gateway that listens for POST requests. This gateway then performs an AWS API call (lambda:InvokeFunction) to invoke the specified lambda function, which than processes the request and determines the subsequent steps of your choice.

But before you do any of that, you first need to verify the authenticity of a request sent to a Discord bot or webhook using the Ed25519 public-key signature system:

    verify_key = VerifyKey(bytes.fromhex(PUBLIC_KEY))
    signature = event['headers']['x-signature-ed25519']
    timestamp = event['headers']['x-signature-timestamp']

    try:
        # ed25519 check
        verify_key.verify(f'{timestamp}{event["body"]}'.encode(), bytes.fromhex(signature))

After which we need to respond to any attempt of verify whether the endpoint is alive:

        # respond to PING with PONG
        if json.loads(event['body'])['type'] == 1:
            return {"type": 1}

Now you have all the ingridients to make a serverless Discord bot running on cloud! The introduction of slash commands by Discord marks a significant step forward for us developers. By integrating AWS Lambda and API Gateway, you can create more scalable, efficient, and powerful bots that respond only when needed while optimizing the resource usage.

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