Servant Auth forces me to use JWT

[mastarija]

This is a bit odd, but I have the following API:

data API mode = API
   { info :: mode :- (Auth '[GWS] ( UserProfile Int ) ) :> "info" :> NamedRoutes InfoAPI
   , template :: mode :- (Auth '[GWS] ( UserProfile Int ) ) :> "template" :> NamedRoutes TemplateAPI
   }
  deriving (Generic)

However, I get this warning when I try to compile the program:

server/Server/Servant.hs:132:14: error:
    • Could not deduce (Servant.Server.Internal.Context.HasContextEntry
                          '[] Servant.Auth.Server.Internal.ConfigTypes.JWTSettings)
        arising from a use of ‘genericServeTWithContext’
      from the context: (Given ServerLib.DatabaseUnitSystem,
                         Given PdxfVersion, Given Reporter, Given ServerLib.Port,
                         Given ServerLib.JwsHmacSecret)
        bound by a type expected by the context:
                   (Given ServerLib.DatabaseUnitSystem, Given PdxfVersion,
                    Given Reporter, Given ServerLib.Port,
                    Given ServerLib.JwsHmacSecret) =>
                   IO ()
        at server/Server/Servant.hs:(121,26)-(132,49)
    • In the second argument of ‘($)’, namely
        ‘genericServeTWithContext trn srv ctx’
      In a stmt of a 'do' block:
        run 8088 $ genericServeTWithContext trn srv ctx
      In the second argument of ‘($)’, namely
        ‘do let trn = flip runReaderT Env
                srv = srvr
                ....
            run 8088 $ genericServeTWithContext trn srv ctx’
    |
132 |   run 8088 $ genericServeTWithContext trn srv ctx
    |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Basically it says I should add JWTSettings to my context (even though I have no JWT auth method defined in the Auth list). And if I do add JWTSettings then it asks me to add the CookieSettings as well, and after that to implement the FromJWT instance for my auth result type:

server/Server/Servant.hs:132:14: error:
    • Could not deduce (ToJWT (UserProfile Flouble))
        arising from a use of ‘genericServeTWithContext’
      from the context: (Given ServerLib.DatabaseUnitSystem,
                         Given PdxfVersion, Given Reporter, Given ServerLib.Port,
                         Given ServerLib.JwsHmacSecret)
        bound by a type expected by the context:
                   (Given ServerLib.DatabaseUnitSystem, Given PdxfVersion,
                    Given Reporter, Given ServerLib.Port,
                    Given ServerLib.JwsHmacSecret) =>
                   IO ()
        at server/Server/Servant.hs:(121,26)-(132,49)
    • In the second argument of ‘($)’, namely
        ‘genericServeTWithContext trn srv ctx’
      In a stmt of a 'do' block:
        run 8088 $ genericServeTWithContext trn srv ctx
      In the second argument of ‘($)’, namely
        ‘do let trn = flip runReaderT Env
                srv = srvr
                ....
            run 8088 $ genericServeTWithContext trn srv ctx’
    |
132 |   run 8088 $ genericServeTWithContext trn srv ctx
    |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

After I provide a bogus implementation of ToJWT it settles down, however, now I'm worried it'll try to use it at some point (haven't tested that out yet).

The problem is a constraint in the Auth HasServer instance which requires me to have a ToJWT instance. I don't see why that should be required.

I would also like to implement my own JWT auth, as I have some legacy auth stuff to deal with and I need to check the database when parsing the JWT, so ToJWT and FromJWT aren't enough, and now I'm worried about how this is going to interact with each other.

[mastarija]

I've just noticed #1576 which mentions this problem and there's #1560 which attempts to address it, so I'm closing this issue.