6 a.m.
On 5/22/2015 3:50 AM, Marko Strukelj wrote:
I like Stian's solution much better ... it's much simpler :)
Yea, to extend the medical metaphor, it's like the guy who goes in to
see the doctor. He raises his arm in a funny way and says, "Hey doc, it
hurts when I do this." Doctor says, "Don't do that."
@Stian: Is there some docs where I can get a better understanding of
what's an API that is exposed to client, and what is implementation
details never to be used by client apps ...
Ideally that would be easy to establish based on package names - e.g.
anything not in org.keycloak.something.impl might be an API, or
nothing but what's in org.keycloak.something.api might be an API ...
Or maybe we have one single module that's client API?
------------------------------------------------------------------------
On 5/21/2015 4:56 PM, Marko Strukelj wrote:
We package examples with jboss-deployment-structure.xml that looks like this:
<jboss-deployment-structure>
<deployment>
<dependencies>
<module name="org.apache.httpcomponents"/>
</dependencies>
</deployment>
</jboss-deployment-structure>
If we drop a .war containing this into Wildfly 9 (distribution/server-dist - ATM
distribution/demo-dist, and distribution/adapters/wildfly-adapter-zip look buggy as they
still use slot=4.3), things are fine.
However, if we dropped this into Wildfly 8 with keycloak adapter modules using
org.apache.httpcomponents slot=4.3, we get a java.lang.LinkageError as soon as some
Keycloak logic is triggered by user app.
The question: how come jboss modules isolation doesn’t kick in and allow keycloak
adapter modules to use slot=4.3 while at the same time user app (our examples) uses
slot=main?
The answer is that org.keycloak.adapters.HttpClientBuilder which seems to be our
helper class for org.apache.httpcomponents inevitably leaks the version of HttpClient its
module refers to - can’t be any other way (unless we change the code to use client app’s
classloader - opening a can of worms). Any user app using HttpClientBuilder.build() method
receives an instance of HttpClient loaded through org.keycloak.keycloak-adapter-core
module, and transitively through org.apache.httpcomponents referred to therein.
Any attempt of an application (.war) to package its own httpcomponents jars, or
to refer to a different jboss module than the exact one referred to by
org.keycloak.keycloak-adapter-core will result in ‘catastrophic failure’. Example:
HttpClient client = new HttpClientBuilder().disableTrustManager().build();
HttpClient on the left is loaded by app’s classloader. The one returned by
build() on the right is loaded by org.keycloak.keycloak-adapter-core module’s version of
httpcomponents. If it’s not the same classloader (jboss module) on both sides loading
HttpClient you get a LinkageError.
In light of this I wonder if it wasn’t the best solution to reexport
org.apache.httpcomponents to .wars by default, thereby removing the necessity to package
jboss-deployment-structure.xml at all, and ensuring that user application always uses the
proper module.
Currently jboss-deployment-structure.xml is required for wildfly / as7, and is a
nuisance, especially as it has to be different (refer to slot=4.3) for Wildfly 8.
If using HttpClientBuilder is supposed to be completely optional, we could maybe
add configuration to keycloak subsystem to control exposing it to all or specific secure
deployments.
We could simply add another common attribute that can be used in <realm>
and <secure-deployment>. We could expose it by default and have something like:
<expose-httpcomponents>false</expose-httpcomponents>
to inhibit exposing it if a situation calls for it.
WDYT?
What do I think? I think that classloading questions always make
my head hurt!
The best solution would be to find a way to detect the problem and
fix it at deploy time. Using a DependencyProcessor, it should be
possible to detect that the deployment contains the same module
from two different slots. Then pick the best slot and spit out a
warning message that you are removing the undesirable module.
It should be possible, but I don't know if it actually IS
possible. A version mismatch between modules is like a cancer. I
think you should speak to an oncologist or David Lloyd. Since Red
Hat doesn't employ any oncologists, go with David. :-)
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