Retry HTTP operation in case IOException too (exponential backoff)

[attilapiros]

Description

Fixing #3291: Retrying the HTTP operation in case of IOException too.

Tested with unit tests.

With the following logger config:

$ cat kubernetes-client/src/test/resources/simplelogger.properties
org.slf4j.simpleLogger.defaultLogLevel=info
org.slf4j.simpleLogger.log.io.fabric8.kubernetes.client.dsl.base = debug

the unit tests produced the following example output (partial output):

[main] DEBUG io.fabric8.kubernetes.client.dsl.base.OperationSupport - HTTP operation on url: https://172.17.0.2:8443/api/v1/pods/test-pod should be retried as the response code was 500, retrying after 2000 millis
[main] DEBUG io.fabric8.kubernetes.client.dsl.base.OperationSupport - HTTP operation on url: https://172.17.0.2:8443/api/v1/pods/test-pod should be retried after 4000 millis because of IOException
java.io.IOException: For example java.net.ConnectException
        at io.fabric8.kubernetes.client.dsl.base.BaseOperationTest.lambda$newHttpClientWithSomeFailures$0(BaseOperationTest.java:245)
        at org.mockito.internal.stubbing.StubbedInvocationMatcher.answer(StubbedInvocationMatcher.java:42)
        at org.mockito.internal.handler.MockHandlerImpl.handle(MockHandlerImpl.java:103)
        at org.mockito.internal.handler.NullResultGuardian.handle(NullResultGuardian.java:29)

Type of change

• Bug fix (non-breaking change which fixes an issue)
• Feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change
• Chore (non-breaking change which doesn't affect codebase;
  test, version modification, documentation, etc.)

Checklist

• Code contributed by me aligns with current project license: Apache 2.0
• I Added CHANGELOG entry regarding this change
• I have implemented unit tests to cover my changes
• I have added/updated the javadocs and other documentation accordingly
• No new bugs, code smells, etc. in SonarCloud report
• I tested my code in Kubernetes
• I tested my code in OpenShift

[centos-ci]

Can one of the admins verify this patch?

[sonarcloud]

Kudos, SonarCloud Quality Gate passed!

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

100.0% Coverage
0.0% Duplication

[rohanKanojia]

@geoand : Would appreciate it if you could review this one since you suggested it.

[geoand]

LGTM!

[shawkins]

Could the cases be combined?

    do {
      IOException ex = null;
      try {
        response = client.newCall(request).execute();
      } catch (IOException e) {
        ex = e;
      }
      doRetry = numRetries < requestRetryBackoffLimit && (response == null || response.code() >= 500);
      if (doRetry) {
        ...
      } else if (ex != null) {
        throw ex;
      }
    } while(doRetry);

[manusa]

LGTM, thx!

[shawkins]

LGTM

Just added the comment/nit about combining the retry cases.

[manusa]

Just added the comment/nit about combining the retry cases.

We can address those separately

[attilapiros]

Thanks for everybody!