[keycloak-dev] in-memory only federated users

[Marek Posolda]

Why it's bad to do simpler things? :-)

AFAIK filter pattern (or interceptor/chain whatever you call it) is 
proven to work in many places. The provider at level X can always decide 
if it delegates call to method "getUserByXXX" to next provider (and then 
proxy/cache or do whatever according to his logic) or return something 
by itself.

If I understand correctly your proposal, it requires 
UserFederationProvider to decide, if it wants to import or just return 
InMemoryUserModel . So if we want to support in-memory for LDAP, we will 
need to have 2 versions of LDAPFederationProvider (current which imports 
into userStorage() and another, which will return InMemoryUserModel 
instances ). That's not ideal IMO.


As I mentioned before, there are also 2 additional usecases, which are 
important to support IMO:

1) Case when admin changes some user attributes directly in LDAP and he 
wants the LDAP data to be immediately visible in Keycloak. This is what 
we currently support (see 
FederationProvidersIntegrationTest.testDirectLDAPUpdate() ). Maybe I am 
missing something with your proposal, but if we hardcode CacheProvider 
to be always first, we lost this.

2) Case when admin doesn't change user attributes in LDAP directly, but 
rather prefer to save performance and read data from cache. In this 
case, admin configures the chain like you proposed: CacheProvider => 
UserFederationManager => UserProvider


IMO it will be cool to have single implementation of 
LDAPFederationProvider (and others), which works for both those cases 
and also for in-memory at the same time. Just let admin to decide how he 
want to configure chain of UserProviders, but not require 
UserFederationProvider itself to care about it.


For my proposal, I assume that UserProvider will have just 2 new methods:

UserProvider getNext();
void setNext(UserProvider next);


Only change in current UserFederationManager and 
DefaultCacheUserProvider is, that they will call "getNext()" when they 
need delegate. They don't care about what the delegate actually is, 
that's not their responsibility.

For the "in-memory" provider, it might be the per-request in-memory 
provider (users stored just per-request). So if you have chain like:
userFederationManager => inMemory

Then assume the session.users().getUserByUsername is called:
1) First delegate is UserFederationManager, so calling 
UserFederationManager.getUserByUsername
2) This line 
https://github.com/keycloak/keycloak/blob/master/model/api/src/main/java/org/keycloak/models/UserFederationManager.java#L180 
will call getNext().getUserByUsername() and returns null as the user was 
not yet looked  for this request.
3) Going to federationProviders and call 
LDAPFederationProvider.getUserByUsername
4) LDAPFederationProvider query user in LDAP and calls 
importUserFromLDAP . This calls session.userStorage().addUser, which 
will put user into in-memory provider (I assume that 
session.userStorage() will be kept and will always point to the next 
delegate after UserFederationManager ). The LDAPFederationProvider will 
then return LDAP proxy of UserModel.

The in-memory provider will also work with searching ( searchUser ) as 
federationLoad will first pre-load users into in-memory and then calls 
"query" and proxy users.

The only limitation I can see now is calling of 
session.users().getUsers() as this doesn't preload users from 
federation. But if people add cache and use chain like:
cache => federationManager => inMemory

it will work fine and find all users retrieved from LDAP in any previous 
requests.


In summary: UserProvider chaining is:

1) Very flexible

2) Supports in-memory, but also other use-cases too. It's all up to 
admin preference how to configure chain

3) No dependencies of providers on each other

4) Minimal changes to UserFederationManager and DefaultCacheUserProvider 
. Just need to call "getNext()" to retrieve next provider

5) Current UserFederationProvider will work fine for all cases and 
automatically gains "in-memory" support without need to change anything 
in their code. Assuming that for backwards compatibility, we will keep 
"session.userStorage()" to always point to next delegate of 
UserFederationManager . If it's JPA, then imports user like now. If it 
will be "in-memory" it will just return cache user for this request and 
return per-request inMemory user.

Marek


On 03/12/15 18:58, Bill Burke wrote:
> Still don't think it is as simple as you state.  We don't need an "in 
> memory" provider.  We want UserFederationProvider to create a 
> temporary request/only in-memory UserModel for federation providers 
> that don't want to import.  This UserModel may be proxied for any 
> write operations.
>
> My current thinking is that we change the flow from:
>
> UserFederationManager=>CacheProvider=>UserProvider
>
> to
>
> CacheProvider->UserFederationManager->UserProvider/UserFederationProvider
>
> KeycloakSession changes:
>
> * users() returns the CacheUserProvider instead of UserFederationManager
> * userStorage() is not changed
> * federationManager() returns UserFederationManager
>
> UserCacheProvider changes:
>
> * Gets a new method cache(UserModel user);
> * References UserFederationManager instead of the DB provider directly
>
> UserFederationManager changes:
> * Instead of calling userStorage(), it gets the DB provider directly
>
> UserFederationProvider:
> * Imports using userStorage() or, allocates a new class 
> InMemoryUserModel (or extension of that class).  This class is just an 
> in memory implementation of UserModel
> * Returns the imported UserModel or the InMemoryUserModel
>
> So
>
> session.users().getUserByXXXX() does the folloing:
>
> 1. UserCacheProvider.getUserByXXX is invoked
> 2. It looks looks in cache, if found return
> 3. invoke UserFederationManager.getUserByXXX
> 4. If UserFederationManager finds it return UserModel
> 5. Look in UserFederationProvider
> 6. UserFederationProvider imports or returns InMemoryUserModel
> 7. UserCacheProvider.getUserByXXX caches the user.
>
> cache.UserAdapter.getDelegateForUpdate() does the following:
> 1. invokes UserFederationManager.getUserById()
> 2. ID is parsed to see if it is a federated ID or not (see original post)
>
> Alternatively, we could just invoke 
> userFederationManager.getUserByusername() since username can't be null.
>
>
>
> On 12/3/2015 11:59 AM, Marek Posolda wrote:
>> On 03/12/15 16:57, Bill Burke wrote:
>>> Either we redo the federation SPI or work with the current one.
>>>
>>> It is just not as simple as you state.  You can't just chain in a
>>> generic InMemoryProvider.  Federation needs to be able to proxy the
>>> UserModel so that it can handle write methods if it wants to. Or
>>> delegate lookup of certain things to LDAP.
>> I am not seeing why it's an issue? The InMemory will be kind of same
>> thing like currently JPA. It just won't store the things into database,
>> but into memory. That's the only difference. It will just be the
>> provider at the end of the chain. UserFederationManager can proxy users
>> exactly like now and doesn't require any code changes.
>>
>> So when admin configure:
>>
>> userFederationMAnager => inMemory
>>
>> The call of "session.userStorage()" from UserFederationManager will
>> return underlying InMemory instead of current JPA.
>>
>>> Also, UserFederationManager has to be first in the chain so that if
>>> something is found in cache, it can let the federation provider proxy
>>> the cache if it wants to.
>> That's not a problem as well.
>>
>> What I mean is the flexibility to configure things exactly how you want
>> for various cases.
>>
>> 3 basic setups:
>>
>> 1. userFederation => cache => JPA
>>
>> This is what we have now and it will be the default setup.  It 's useful
>> for deployments when admins are often doing changes directly in their
>> LDAP and they want the change imediatelly visible in Keycloak. So the
>> UserFederationProvider proxy is always the top and when you call:
>>
>> user.getFirstName()
>>
>> you will retrieve the firstName from LDAP. The disadvantage of this
>> setup is performance (each HTTP request needs to query LDAP like it's 
>> now)
>>
>>
>> 2. cache => userFederation => JPA
>>
>> This will be useful for deployments when amins are not doing changes
>> directly in their LDAP. So once you retrieve the user from
>> LDAP+KeycloakDB, you will save him to cache and call to:
>>
>> user.getFirstName()
>>
>> will always return the value from cache. Hence when admin changes
>> directly in LDAP, it won't be immediately visible in Keycloak.
>>
>> But on the other hand update from Keycloak to LDAP is not an issue. When
>> you call:
>>
>> user.setFirstName("foo")
>>
>> the cache will call getDelegateForUpdate (exactly like now) and it will
>> return proxy object, so the saving of firstName is propagated to LDAP
>> (if it's writable) and to Keycloak JPA DB as well.
>>
>>
>> 3. userFederation => inMemory
>>
>> The federation backed by pure in-memory storage. The federation proxy is
>> on top, writing and reading to/from LDAP is not a problem and has
>> preference over the content from memory. The only difference from (1) is
>> that underlying backend is pure memory (infinispan) instead of JPA DB
>>
>> There is also alternative to use combination of 2 and 3:
>> cache => userFederation => inMemory
>>
>> etc etc.
>>
>>
>> I can see this as most flexible approach without dependencies of various
>> providers on each other.
>>
>> Marek
>>>
>>> What we need is a special interface for the cache:
>>>
>>> cache.cacheUser(UserModel user);
>>>
>>> The cache would also work with UserFederationManager rather than a
>>> generic UserProvider. UserFederationManager would gain methods like:
>>> UserFederationManager.getUncachedUserById() which the cache would
>>> invoke.  UserFederationManager would break down the user id and either
>>> know it was local storage or something that would have to be delegated
>>> to a UserProvider.
>>>
>>>
>>>
>>>
>>>
>>> On 12/3/2015 10:32 AM, Marek Posolda wrote:
>>>> IMO the more important use-case that in-memory federated users is the
>>>> caching of federated users.
>>>>
>>>> Currently if you call: session.users().getUserById() and the user with
>>>> ID "123" is LDAP (or other federationProvider) user, there is always
>>>> call to UserFederationProvider.validateAndProxy , which results in 
>>>> LDAP
>>>> query.
>>>>
>>>> If we introduce the chaining of UserProvider (something I already
>>>> proposed earlier), you can switch UserFederationProvider with 
>>>> cache, so
>>>> you will have:
>>>> cache => userFederationManager => JPA
>>>>
>>>> instead of current:
>>>>
>>>> userFederationManager => cache => JPA
>>>>
>>>>
>>>> With that in mind, we can easily implement in-memory as another
>>>> implementation of UserProvider, which will hold users purely 
>>>> in-memory.
>>>> Our current DefaultCacheUserProvider always require delegate to call
>>>> write operations. But this in-memory provider would be something
>>>> different. It won't use any delegate as it will be in the end of the
>>>> chain. So for in-memory federation you will just configure:
>>>>
>>>> userFederationManager => inMemoryProvider
>>>>
>>>> and you're done. No needs for special ID handling or something like
>>>> that.
>>>>
>>>> With chaining of UserProvider we have biggest flexibility for various
>>>> needs IMO. That's why I would rather go this way TBH.
>>>> Marek
>>>>
>>>> On 02/12/15 17:48, Bill Burke wrote:
>>>>> I'm looking into in-memory only no-import federated users.  What we
>>>>> would want to do is allow the UserFederationProvider to create an
>>>>> in-memory UserModel and allow for that UserModel to be cached via our
>>>>> current architecture.
>>>>>
>>>>> The current design assumes that all federated users are imported.  
>>>>> This
>>>>> includes our caching layer too!  To add to that, the user isn't 
>>>>> cached
>>>>> until the 2nd request i.e.:
>>>>>
>>>>> 1. username/password page would hit the UserFederationProvider and 
>>>>> the
>>>>> user would be imported into Keycloak.  This imported user is not
>>>>> cached,
>>>>> only imported into the database for this request's KeycloakSession
>>>>> 2. OTP Page or code 2 token would then want to lookup the user by 
>>>>> id as
>>>>> that is what is stored in the ClientSession.  It would hit the 
>>>>> keycloak
>>>>> database as it is not cached yet.  This lookup loads the cache for
>>>>> the user.
>>>>>
>>>>> Getting in-memory zero-import to work is even more tricky. The 
>>>>> issue is
>>>>> that ClientSession and UserSession need to lookup clients by id.  If
>>>>> the
>>>>> user is not in cache, then the cache needs to lookup the user by id
>>>>> within storage.  This lookup also needs to happen if a write 
>>>>> operation
>>>>> is performed on a cache user (getDelegateForUpdate()). So, Keycloak
>>>>> needs to know that that ID is not in local storage and must be
>>>>> looked up
>>>>> from a fed provider.  The ID must be formed so that the provider fed
>>>>> provider can resolve the lookup.  I could use a URI for the ID i.e.
>>>>>
>>>>> fed:{providerId}:{login-name}
>>>>>
>>>>> The problem with this is that this id would need to be larger than 36
>>>>> characters which is the current column size for UserEntity.id and any
>>>>> other table that references users.   I could possibly do:
>>>>>
>>>>> fed:{providerAlias}:{login-name}
>>>>>
>>>>> But its quite possible that combination would be larger than 36
>>>>> characters.  We could also just shrink it to:
>>>>>
>>>>> fed:{login-name}
>>>>>
>>>>> But then we would have to iterate over every federation provider to
>>>>> find
>>>>> and load the user.
>>>>>
>>>>> So in summary:
>>>>> * IDs need to expand from 36 characters to something larger. (255
>>>>> maybe).  Don't some DBs have constraints on string primary key
>>>>> size?  DB
>>>>> scripts could possibly be
>>>>> * CachedUserProvider and UserFederationManager interfaces would 
>>>>> need to
>>>>> be refactored
>>>>> * I don't think UserFederationProvider interface would need to 
>>>>> change.
>>>>> But users would have to code for in-memory rather than throwing a
>>>>> switch
>>>>> to just turn it on.
>>>>>
>>>>>
>>>>>
>>>>
>>>
>>
>

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