dynamo

The dynamo service is responsible for generating images and other resources based on user-submitted prompts. These generated resources are typically used for alerts that appear on-screen during streams.

In constrast to typical static alerts, these types of alerts:

• Require generating dynamic content before the alert can be displayed, which is typically a long-running background process which may fail or require retries
• Depend on external services which may be unavailable or subject to rate limiting, requiring robust backoff and retry
• May fail due to impermissible prompts or the detection of objectionable content

The dynamo service is designed to account for these constraints:

• It queues generation requests in order to respect rate limits and handle retries automatically and in an orderly fashion
• It handles one of two eventual end states: success, in which case an alert is displayed on the stream; or failure, in which case the user is notified that their request was inadmissible
• It coordinates with the ledger service to ensure that Golden VCR Fun Point costs are debited only upon success

The dynamo-consumer process consumes events from the generation-requests RabbitMQ exchange, constructing prompts and submitting them to the OpenAI API in order to generate the desired assets. Once assets are successfully generated, the requisite Golden VCR Fun Points are deducted from the user's balance, and an alert is initiated by producing a message to the onscreen-events exchange.

The dynamo server process allows HTTP clients to obtain information about existing generation requests and to requests to the queue manually, outside of the Twitch event pipeline. State pertaining to asset generation requests is stored in a PostgreSQL database schema called dynamo.

Prerequisites

Install Go 1.21. If successful, you should be able to run:

> go version
go version go1.21.0 windows/amd64

Initial setup

Create a file in the root of this repo called .env that contains the environment variables required in main.go. If you have the terraform repo cloned alongside this one, simply open a shell there and run:

• terraform output -raw auth_shared_secret_env >> ../dynamo/.env
• terraform output -raw openai_api_env >> ../dynamo/.env
• terraform output -raw user_images_s3_env >> ../dynamo/.env
• ./local-rmq.sh env >> ../dynamo/.env
• ./local-db.sh env >> ../dynamo/.env

The dynamo service depends on both RabbitMQ and PostgreSQL: you can start up local versions for development (in a docker container) by running ./local-rmq.sh up and ./local-db.sh up.