[FLINK-22630] Different com.squareup.okhttp3:okhttp dependency versions might lead to version conflicts with io.fabric8:kubernetes-server-mock

• Type: Improvement
• Status: Closed
• Priority: Minor
• Resolution: Not A Problem
• Affects Version/s: 1.14.0
• Component/s: Build System
• Assignee: Unassigned
• Reporter: Matthias Pohl
• Created: 11/May/21 08:40
• Updated: 04/Aug/21 11:01
• Resolved: 04/Aug/21 11:01

Description

I ran into the following issue when executing Fabric8FlinkKubeClientTest in a test suite from a different flink module that has com.squareup.okhttp3:okhttp set as a dependency (more specifically in my case flink-runtime's ZooKeeperStateHandleStoreTest) from within Intellij:

Exception in thread "MockWebServer" java.lang.NoSuchFieldError: H2_PRIOR_KNOWLEDGE
	at okhttp3.mockwebserver.MockWebServer$3.processConnection(MockWebServer.java:499)
	at okhttp3.mockwebserver.MockWebServer$3.execute(MockWebServer.java:443)
	at okhttp3.internal.NamedRunnable.run(NamedRunnable.java:32)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at java.lang.Thread.run(Thread.java:748)

Interestingly, the test didn't fail when executing it from command line:

mvn -pl flink-runtime,flink-kubernetes test -Dtest=Fabric8FlinkKubeClientTest,ZooKeeperStateHandleStoreTest -Dfast

Fabric8FlinkKubeClientTest also doesn't fail if running multiple tests of flink-kubernetes.

The issue is caused by the MockWebServer implementation. I found a hint on StackOverflow indicating that io.fabric8:kubernetes-server-mock uses com.squareup.okhttp3:mockwebserver internally which leads to the version clash and the error shown above.

I checked the other dependencies and realized that we use com.squareup.okhttp3:okhttp in multiple modules and that Intellij adds all of these dependencies versions to the classpath. My conclusion was that there might be a version conflict accessing the wrong dependency version when loading the dependencies for the test execution that results in the error shown above.

I verified my finding by updating the version for all {{com.squareup.okhttp3:okhttp dependencies to 1.12.6 which is used in flink-kubernetes and reloaded the Maven dependencies within Intellij. This made the above mentioned test suite containing Fabric8FlinkKubeClientTest in a test suite from a different flink module that has com.squareup.okhttp3:okhttp and ZooKeeperStateHandleStoreTest succeed.