I made an app and gave it an address like address.fly.dev.
I realized it wasn’t working properly and fixed it. I could not re-serve it to address.fly.dev, so I put it on address1.fly.dev, where it is working as intended.
How do I reset the address.fly.dev address so I can use it?
Thank you!
Hi,
The sub-domain [appname].fly.dev is simply the app’s name. So if you have created a new app called e.g newappname, that will have been assigned its own, separate [newappname].fly.dev.
As far as I’m aware the provided sub-domain can’t be re-pointed at another app. Since the app’s name (and hence sub-domain) needs to be globally unique 
.
You could either re-deploy (not quite yet, as there is an issue) your working code to your old app’s name (and so then it would be served under the old app’s sub-domain too).
Or if that’s not possible, you could provide a custom domain (Fly provide the SSL certificate for that). In which case you are then free to point that at any app name. Because you control the DNS records and so e.g could CNAME your-domain.com to any app-name.fly.dev.
Hi, thanks for your response.
No, that’s what I tried. It doesn’t work.
How do I do that?
Hi,
Take a look at Custom Domains and SSL Certificates · Fly Docs
As that guide says, if you want to use a custom domain, you can either use a CNAME or A/AAAA record.
Depending who provides your DNS (likely - but not necessarily - who you registered the domain with), the UI to actually do that will vary. For example in Cloudflare you would click on your domain in their dashboard, then on DNS. And be presented with a list of DNS records. And you’d click the button to add one.
Usually it would simply ask for your chosen subdomain (let’s say ‘www’), what type of record to add (for example CNAME), and where it should point to (so here that would be your-app-name.fly.dev):
www.your-domain.com CNAME your-app-name.fly.dev
The other way is using A/AAAA records (IPv4/IPv6). Your app gets an assigned IPv4 for the A record and IPv6 for the AAAA record. Again, how you provide those to your DNS provider will vary depending who it is. But the process will be like a CNAME. Except here when asked for the type of record to add, you would select A or AAAA. And provide the values.
The second step is SSL. Since you will likely want https://www.your-domain.com
Fly can provide you with an SSL certificate. But of course it needs to be told to. So if you scroll down that guide linked above, you can see the approaches for doing that. If you have added A/AAAA records already, that should be sufficient to pass validation and for Fly to issue the certificate within minutes. If you have used a CNAME instead, you may need to add another DNS record, another CNAME pointed at something.flydns.net. Or whatever it tells you.
I seem to have set up something incorrectly in my Procfile – I have now made a change and the app is now functioning as desired at the original address. Thanks again!