It's possible to have a shared Docker image for multiple Prefect flows. The recommended approach is to build a custom image that includes all necessary dependencies and shared task definitions. Your flows can rely on the same image but have their source code stored externally, which can facilitate development because the shared image only needs to be rebuilt when dependencies change, not when the flow source changes.
For detailed instructions on how to set up a Docker environment for Prefect flow deployments, please refer to the Prefect documentation:
Docker image multiple Prefect flows.
Remember, though, that if different flows have wildly different dependencies or system-level requirements, maintaining separate images could be beneficial to avoid potential conflicts. However, if the flows share common dependencies and environment, a single Docker image could be more manageable and efficient.