I just need to run a dataflow pipeline on a daily basis, but it seems to me that suggested solutions like App Engine Cron Service, which requires building a whole web app, seems a bit too much. I was thinking about just running the pipeline from a cron job in a Compute Engine Linux VM, but maybe that's far too simple :). What's the problem with doing it that way, why isn't anybody (besides me I guess) suggesting it?
There's absolutely nothing wrong with using a cron job to kick off your Dataflow pipelines. We do it all the time for our production systems, whether it be our Java or Python developed pipelines.
That said however, we are trying to wean ourselves off cron jobs, and move more toward using either AWS Lambdas (we run multi cloud) or Cloud Functions. Unfortunately, Cloud Functions don't have scheduling yet. AWS Lambdas do.