[keycloak-dev] Thinking about a change to providers

Thu Jun 23 09:40:33 EDT 2016

On 23 June 2016 at 15:33, Marek Posolda <mposolda at redhat.com> wrote:

> On 23/06/16 14:28, Stian Thorgersen wrote:
>
>
>
> On 23 June 2016 at 14:19, Marek Posolda <mposolda at redhat.com> wrote:
>
>> +1 on having "invalidateProvider" method.
>>
>> For the other stuff,  we already have the first 2 "getProvider" methods,
>> so the new stuff will be the methods with "String instanceId" parameter,
>> right?
>>
>
> Yes, I just included the two existing methods to point out that they will
> still be there.
>
>
>>
>> We already discuss adding the "String instanceId" . Now when thinking
>> more, it looks that it is not so convenient.
>>
>> When adding again UserFederation SPI as an example:
>>
>> - UserFederationProviderFactory needs UserFederationProviderModel to
>> create instance of UserFederationProvider
>> - So factory needs to lookup model from cache/db. Hence the instanceId
>> would need to be compound of something like:
>> <REALM-UUID>::<USER-FEDERATION-PROVIDER-MODEL-ID>
>> That's because to lookup UserFederationProviderModel, you first need
>> RealmModel and then find the UserFederationProviderModel by it's ID within
>> the realm.
>>
>> You may admit that RealmModel is available on KeycloakContext. However I
>> don't think that we can rely on it. KeycloakContext is available in REST
>> requests, but in some other cases (ie. ExportImport, periodic tasks etc),
>> it's not available. Caller usually have the RealmModel and he can manually
>> set it to KeycloakContext before calling session.getProvider, however that
>> doesn't look like good approach to me and should be rather avoided. So in
>> shortcut, we shouldn't rely on realm being available in KeycloakContext
>> IMO.
>>
>
> Going forward we should rely on the realm being available in
> KeycloakContext IMO. The whole purpose of it is so we don't have to pass
> details around all the time, including the realm.
>
> I see two options to it:
>
> * Don't require the realm to load provider config. If instances ids are
> UUIDs this would work, but I don't think they always are right?
>
> Even if they are just UUID, we will require to refactor model and have all
> the models lookup methods (e.g. "getUserFederationPRoviderModel",
> "getIdentityProviderModel" ) available globally on RealmProvider rather
> than on RealmModel. Not sure if it's very good, especially since in admin
> console, you create providers per particular realm.
>
> * Add RealmModel to the lookup, so it becomes:
>   getProvider(Class<T> clazz, String providerId, RealModel realm, String
> instanceId)
>   That would also require a invalidateProviders(RealmModel realm) that
> can clear all provider instances for a specific realm
>
> Not sure adding RealmModel is sufficient... Some providers might not be
> scoped per-realm but rather per-client though. For example recently added
> authz based ResourceServer is scoped per client, so I can imagine it can be
> valid use-case to have providers scoped per-client as well.
>

Not sure why a provider should be scoped per-client. A ResourceServer in
either case it's an internal thing and there should be a
getResourceServer(ClientModel client) rather than
getProvider(ResourceServer..). Not sure what the code does now though.

>
>
>
>>
>> The logic for parse the "instanceId" and retrieve
>> UserFederationProviderModel from DB would be boilerplate code same to all
>> UserFederationProviderFactory impls.
>>
>>
>> With that in mind, it really seems to me that instead of "String
>> instanceId", it may work better to have some common configuration class
>> like "ProviderModel" . Then signature will look like:
>>
>> * getProvider(Class<T> clazz, String providerId, ProviderModel  model)
>>
>> All the model subclasses (UserFederationProviderModel,
>> IdentityProviderModel, PasswordPolicyModel ...) will be subclasses of
>> ProviderModel
>>
>
> I don't like that at all as it requires loading and retrieving the model
> to be able to get the instance. It should be the responsibility of the
> factory and provider framework to be able to do that, not the code that
> wants to use the provider.
>
> Well, I don't see that as an issue, but rather an advantage. It's better
> if model is loaded by caller rather than an implementation. So the custom
> UserFederationProviderFactory (or IdentityProviderFactory) implemented by
> customers don't need to contain same code for lookup the model based on
> instanceId String.
>

It's basic principals of dependency injection and loosely coupling to not
require knowing how to create something to be able to use it. I strongly
disagree that the calling code needs to know how to load the config. There
are multiple places that may need to use a provider, which would then
require all those places to be able to load the config. Further, not all
providers may want to use the model directly. If it's up to the factory
itself to load the config the config can be located elsewhere.

>
>
> Marek
>
>
>> Marek
>>
>>
>> On 23/06/16 12:01, Stian Thorgersen wrote:
>>
>> Currently it's expected that the factory is application scoped, while
>> provider instances are request scoped. Factories can if they want return
>> the same instance for provider to make it application scoped.
>>
>> This works as long as config is server-wide, but not if there are config
>> per-realm or even multiple different instances per-realm. This applies to
>> for example User Federation SPI (multiple per-realm), Password Hashing SPI
>> (one per-realm), etc.
>>
>> Currently the User Federation SPI creates and manages instances outside
>> of the session factory and session, which results in multiple instances
>> created per-request, not all being closed properly, etc..
>>
>> With that in mind I'd like to change the provider factories so that there
>> can be multiple provider factory instances. It's not completely figured
>> out, but I wanted to discuss it before I start a POC around it.
>>
>> We'd have the following methods on KeycloakSession:
>>
>> * getProvider(Class<T> clazz, Provider.class) - returns default provider
>> * getProvider(Class<T> clazz, Provider.class, String providerId) -
>> returns a specific provider, with the default config
>> * getProvider(Class<T> clazz, Provider.class, String providerId, String
>> instanceId) - returns a specific provider, with the specific config
>>
>> We'd also add a method:
>>
>> * invalidateProvider(Class<T> clazz, Provider.class, String providerId,
>> String instanceId) - this would be called when the config for a specific
>> provider instance is updated
>>
>> Behind the covers the instances would be maintained. Each provider
>> factory would internally be responsible to retrieve config and cache config
>> for instances.
>>
>> Does this sound like an idea worth pursuing? I'd like to try it out on
>> the PasswordPolicy SPI first.
>>
>>
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>>
>>
>>
>
>
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