NIFI-4889: Logout not working properly with OIDC

[Trojan295]

• Redirect user agent to end session endpoint on the OIDC provider

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[Trojan295]

When running the test suite locally I have problems with an dependency:

[ERROR] Failed to execute goal on project nifi-hive-processors: Could not resolve dependencies for project org.apache.nifi:nifi-hive-processors:jar:1.7.0-SNAPSHOT: Could not find artifact org.pentaho:pentaho-aggdesigner-algorithm:jar:5.1.5-jhyde in central (https://repo1.maven.org/maven2) -> [Help 1]

I had to add an additional repository to make it work, although I didn't commit it:

<repository>
    <id>spring-plugins</id>
    <url>http://repo.spring.io/plugins-release</url>
    <snapshots>
        <enabled>false</enabled>
    </snapshots>
    <releases>
        <enabled>true</enabled>
    </releases>
</repository>

Could it be, that the artifact was in Maven Central and was moved, but the CI on Travis as it cached in the local repo?

[pvillard31]

@Trojan295 - NiFi 1.7.0 has been released, I'd recommend you to rebase against master (so that all the pom files are updated to 1.8.0-SNAPSHOT) and do a full build to have a clean local maven repo (you shouldn't have 1.7.0-SNAPSHOT anymore). All the Travis builds are OK for your PR so it sounds OK to me.

Regarding the PR itself, I'll let someone like @mcgilman having a look ;)

[Trojan295]

Rebased from current master

[mcgilman]

Will review...

[mcgilman]

@Trojan295 Thanks for the PR! The code looks good but I ran into an issue when attempting to log out. Despite being a required field in the openid spec [1], it appears that at least in practice [2] the end_session_endpoint field is not guaranteed to be present. I think we may need to account for this possibility in the logout endpoint.

[1] https://openid.net/specs/openid-connect-session-1_0.html#OPMetadata
[2] https://accounts.google.com/.well-known/openid-configuration

[Trojan295]

I added a fallback to simply redirect back to NiFi in case the end session endpoint isn't present.

Tricky thing is, that NiFi automatically starts an login attempt, when an unauthenticated user accesses NiFi. In case of an IDP like Keycloak, which has the end session endpoint, then after logout the user is redirected back to Keycloaks login page.

In case of Google OpenID he gets redirected to them and the SSO mechanism logs the user again...

[mcgilman]

Looks good @Trojan295. Thanks! This has been merged to master.