Constructing a new OAuth2/OIDC Identity Provider from the ground up is an undertaking fraught with complexity – and not of the elegant variety. The reasons are numerous, entrenched, and maddeningly persistent.
1. OAuth2 and OIDC are inherently intricate and alarmingly brittle – the specifications, whilst theoretically robust, leave sufficient ambiguity to spawn implementation chaos.
2. The proliferation of standards results in the absence of any true standard – token formats and claim structures vary so wildly that the notion of consistency becomes a farce – a case study in design by committee with no enforcement mechanism.
3. ID tokens and claims lack uniformity across providers – interoperability, far from being an achievable objective, has become an exercise in futility. Every integration must contend with the peculiarities – or outright misbehaviours – of each vendor’s interpretation of the protocol. What ought to be a cohesive interface degenerates into a swamp of bespoke accommodations.
4. There is no consensus on data placement – some providers, either out of ignorance or expedience, attempt to embed excessive user and group metadata within query string parameters – a mechanism limited to roughly 2k characters. The technically rational alternative – the UserInfo endpoint – is inconsistently implemented or left out entirely, rendering the most obvious solution functionally unreliable.
Each of these deficiencies necessitates a separate layer of abstraction – a bespoke «adapter» for every Identity Provider, capable of interpreting token formats, claim nomenclature, pagination models, directory synchronisation behaviour, and the inevitable, undocumented bugs. Such adapters must then be ceaselessly maintained, as vendors alter behaviour, break compatibility, or introduce yet another poorly thought-out feature under the guise of progress.
All of this – the mess, the madness, and the maintenance burden – is exhaustively documented[0]. A resource, I might add, that reads less like a standard and more like a survival manual.
[0] https://www.pomerium.com/blog/5-lessons-learned-connecting-e...