kvstore: Fix event watcher serialization

[joestringer]

When using the watcher in log messages with JSON-based logging, logrus
would give up on trying to generate the log message and print this to
the logs instead:

Failed to obtain reader, failed to marshal fields to JSON, json:
unsupported type: kvstore.EventChan

Fix it by fixing the JSON serialization tags to the structure to avoid
serializing fields that don't make sense to be serialized, and to export
the fields that do make sense to be serialized.

Manually tested by applying this diff:

diff --git a/pkg/kvstore/base_test.go b/pkg/kvstore/base_test.go
index e9ee7da296bf..eb5a3548039b 100644
--- a/pkg/kvstore/base_test.go
+++ b/pkg/kvstore/base_test.go
@@ -292,3 +292,10 @@ func (s *BaseTests) TestListAndWatch(c *C) {

        w.Stop()
 }
+
+func (s *BaseTests) TestFoo(c *C) {
+       w := ListAndWatch(context.TODO(), "testWatcher2", "foo2/", 100)
+       c.Assert(c, Not(IsNil))
+
+       log.WithField(fieldWatcher, w).Fatal("Stopped watcher")
+}
diff --git a/pkg/logging/logging.go b/pkg/logging/logging.go
index 9989e8db0280..6a651c0c87f4 100644
--- a/pkg/logging/logging.go
+++ b/pkg/logging/logging.go
@@ -50,7 +50,7 @@ const (

        // DefaultLogFormat is the string representation of the default logrus.Formatter
        // we want to use (possible values: text or json)
-       DefaultLogFormat LogFormat = LogFormatText
+       DefaultLogFormat LogFormat = LogFormatJSON
 )

 var (

Fixes: #14028

[fristonio]

LGTM 🥳

[nathanjsweet]

test-me-please

[aanm]

retest-gke

EDIT: Provisioning failure.

[joestringer]

retest-gke

EDIT: Provisioning failure.

[joestringer]

I don't see a way that the GKE build could fail while the others are all successful, so given the problems with running GKE CI runs right now I think it's reasonable to bypass that check and merge.

[errordeveloper]

retest-gke

[errordeveloper]

GKE Failed again, and it definitely looks unrelated.

===================== Exiting AfterFailed =====================
15:24:30 STEP: Running AfterEach for block EntireTestsuite K8sServicesTest
FAIL: terminating containers are not deleted after timeout
Expected
    <*errors.errorString | 0xc0004bdd40>: {
        s: "Pods are still not deleted after a timeout: 4m0s timeout expired",
    }
to be nil
15:28:30 STEP: Running AfterEach for block EntireTestsuite