This demos a hacky way to get around SAM CLI's current shortfall with volume mounts.
- Spin up your function with docker or docker compose. Make sure it has the Lambda Runtime Interface Emulator.
- Use sam to spin up a proxy to call your function.
- Use template.prod.yaml for deployments and to spin up your function without mount.
Mount volumes however you need to in your docker-compose file.
docker-compose up
sam local start-api --parameter-overrides HostIP=<Your Host IP>
Note, it's best to mount all volumes as readonly except for a mount to /tmp to replicate Lambda.