I’ve always seen localhost and 127.0.0.1 as the same thing. It’s definitely the same location. But I hadn’t considered that it may be seen as a different host. In fact, I’m still not sure if it is, or even if it should be.
I’ve spent a couple of days debugging some weird issues with Ory Hydra. Let’s set aside the fact that it uses OAuth2, but what seems to be in an unconventional way. I need to make about six http requests to get a token. I don’t know if that’s normal for an identity provider, but it seems excessive.
The issue I ran into was within those six calls, localhost and 127.0.0.1 had gotten used interchangeably. I received various error messages. Everything from telling me the error is indistinguishable to errors about an unknown client, or errors about CSRF tokens.
While googling the error messages over and over, just looking for a sliver of hope, I saw a comment that fixed everything.
Turns out Hydra sees localhost and 127.0.0.1 as different hosts, but doesn’t complain about an unknown host. That might have led me down the right path sooner. And I never use 127.0.0.1, so I’m pretty sure that was a config setting when I was using the 5 minute tutorial to set everything up.
Make sure to check what host you are passing around when setting up Hydra.