app name restrictions

What are the restrictions on fly app names? I keep getting either invalid name errors on app creation or opaque failures during deploy. So far I’ve determined that lowercase alphas, digits and ‘_’ are ok. Would be great if there were more valid chars. Also, I can create apps with longish names but get “unknown error” on deploy.

For example

image size: 753 MB
==> Creating release
Error An unknown error occured.

App names just need to be valid for dns.

We’re looking into the unknown error!

Thanks. Makes sense. I assume no '.'s either right? It always surprises me that ‘_’ are not valid in dns names.

For the unknown error, i was wondering if it was a length thing. I took the same app, shortened the name and it deployed fine. Totally makes sense there would be a limit. It’d be great to know that limit.

I just checked and we don’t have a limit set, which we probably should add. I can’t find an error in Sentry for what you see, but if I had to guess the app name is too long :slight_smile:

You can definitely put a _ in a DNS label (we have a bunch of names like that, like _apps.internal, because we were dumb and camped the whole .internal TLD for apps, instead of doing or something).

But you can’t do it here, because we rely on _ being a reserved character we can use for our own stuff. :slight_smile:

Following up a bit. I suspect that, while the name was fine as an app name, it was not so good as a machine name. It seems that each label (segment) in an FQDN has be <64 chars. My app name was 80 chars. If that’s true, you might want to add a length check in app name validation