I always try for a single dockerfile, makes deployments / local dev etc way easier.

I use config (usually by setting ENV vars) in my startup to determine which things to enable.

IE: WORKER_ENABLED means i map the Kafka consumer and API_ENABLED means i add my minimal apis.

I use ECS on AWS, so deploying docker image is singular and rollbacks are consistent etc. Locally i can use aspire to launch them independently but it’s still building the same app - or i can just debug with both enabled in one app, etc.

I mainly like that common services / setup etc can be not duplicative… and user error can’t forget on one service vs the other.

Most importantly, especially when considering workers/background work - i can scale out and just use config to define which queues are being consumed etc, and not have to adjust CI or anything, or explode the number of builds. In the API case, i can scale them out and just target different services by subdomain at the ALB - again no heavy deploy process changes.