refactor: extract OpenShift version detection to a method

Author: petr-muller

pkg/featuregates/featuregates.go

@@ -5,6 +5,12 @@ import (
 	"github.com/openshift/api/features"
 )
 
+// StubOpenShiftVersion is the default OpenShift version placeholder for the purpose of determining
+// enabled and disabled CVO feature gates. It is assumed to never conflict with a real OpenShift
+// version. Both DefaultCvoGates and CvoGatesFromFeatureGate should return a safe conservative
+// default set of enabled and disabled gates, typically with unknownVersion set to true.
+const StubOpenShiftVersion = "0.0.1-snapshot"
+
 // CvoGateChecker allows CVO code to check which feature gates are enabled
 type CvoGateChecker interface {
 	// UnknownVersion flag is set to true if CVO did not find a matching version in the FeatureGate

pkg/start/start.go

@@ -189,31 +189,7 @@ func (o *Options) Run(ctx context.Context) error {
 		return err
 	}
 
-	payloadRoot := payload.DefaultRootPath
-	if o.PayloadOverride != "" {
-		payloadRoot = payload.RootPath(o.PayloadOverride)
-	}
-
-	cvoOpenShiftVersion := "0.0.1-snapshot"
-	// Peek at the local release metadata to determine the version of OpenShift this CVO belongs to. This assumes the CVO is
-	// executing in a container from the payload image. Full payload content is only read later once leader lease is
-	// acquired, and here we should only read as little data as possible to determine the version so we can establish
-	// enabled feature gate checker for all following code.
-	//
-	// We cannot refuse to start CVO if for some reason we cannot determine the OpenShift version on startup from the local
-	// release metadata. The only consequence is we fail to determine enabled/disabled feature gates and will have to use
-	// some defaults.
-	releaseMetadata, err := payloadRoot.LoadReleaseMetadata()
-	switch {
-	case err != nil:
-		klog.Warningf("Failed to read release metadata to determine OpenShift version for this CVO (will use placeholder version %q): %v", cvoOpenShiftVersion, err)
-	case releaseMetadata.Version == "":
-		klog.Warningf("Version missing from release metadata, cannot determine OpenShift version for this CVO (will use placeholder version %q)", cvoOpenShiftVersion)
-	default:
-		cvoOpenShiftVersion = releaseMetadata.Version
-		klog.Infof("Determined OpenShift version for this CVO: %q", cvoOpenShiftVersion)
-	}
-
+	_ = o.getOpenShiftVersion()
 	clusterVersionConfigInformerFactory, configInformerFactory := o.prepareConfigInformerFactories(cb)
 
 	// initialize the controllers and attempt to load the payload information
@@ -237,6 +213,35 @@ func (o *Options) prepareConfigInformerFactories(cb *ClientBuilder) (configinfor
 	return clusterVersionConfigInformerFactory, configInformerFactory
 }
 
+// getOpenShiftVersion peeks at the local release metadata to determine the version of OpenShift this CVO belongs to.
+// This assumes the CVO is executing in a container from the payload image. This does not and should not fully load
+// whole payload content, that is only loaded later once leader lease is acquired. Here we should only read as little
+// data as possible to determine the version so we can establish enabled feature gate checker for all following code.
+func (o *Options) getOpenShiftVersion() string {
+	payloadRoot := payload.DefaultRootPath
+	if o.PayloadOverride != "" {
+		payloadRoot = payload.RootPath(o.PayloadOverride)
+	}
+
+	// We cannot refuse to start CVO if for some reason we cannot determine the OpenShift version on startup from the local
+	// release metadata. The only consequence is we fail to determine enabled/disabled feature gates and will have to use
+	// some defaults.
+	releaseMetadata, err := payloadRoot.LoadReleaseMetadata()
+	if err != nil {
+		klog.Warningf("Failed to read release metadata to determine OpenShift version for this CVO (will use placeholder version %q): %v", featuregates.StubOpenShiftVersion, err)
+		return featuregates.StubOpenShiftVersion
+	}
+
+	if releaseMetadata.Version == "" {
+		klog.Warningf("Version missing from release metadata, cannot determine OpenShift version for this CVO (will use placeholder version %q)", featuregates.StubOpenShiftVersion)
+		return featuregates.StubOpenShiftVersion
+	}
+
+	klog.Infof("Determined OpenShift version for this CVO: %q", releaseMetadata.Version)
+	return releaseMetadata.Version
+
+}
+
 // run launches a number of goroutines to handle manifest application,
 // metrics serving, etc.  It continues operating until ctx.Done(),
 // and then attempts a clean shutdown limited by an internal context