This is probably a perfect use-case for what we're discussing in #22, or even for a new environment variable to be able to specify arguments to be passed to initdb (something like POSTGRES_INITDB_ARGS="--data-checksums"; since from what I can see, this just needs --data-checksums passed to the initdb invocation).

Looking at the docs, it looks like --data-checksums can only be passed to initdb; there isn't a way to do it after initialization. That makes me think that the change in #22 / #23 won't help here. It will need something like POSTGRES_INITDB_ARGS.