Restore "auto" version for upgrade cluster (#2464)

pkg/ctl/upgrade/cluster.go

@@ -137,7 +137,8 @@ func requiresVersionUpgrade(clusterMeta *api.ClusterMeta, currentEKSVersion stri
 	}
 
 	// If the version was not specified default to the next Kubernetes version and assume the user intended to upgrade if possible
-	if clusterMeta.Version == "" {
+	// also support "auto" as version (see #2461)
+	if clusterMeta.Version == "" || clusterMeta.Version == "auto" {
 		if api.IsSupportedVersion(nextVersion) {
 			clusterMeta.Version = nextVersion
 			return true, nil
@@ -149,7 +150,7 @@ func requiresVersionUpgrade(clusterMeta *api.ClusterMeta, currentEKSVersion stri
 	}
 
 	if c, err := utils.CompareVersions(clusterMeta.Version, currentEKSVersion); err != nil {
-		return false, err
+		return false, errors.Wrap(err, "couldn't compare versions for upgrade")
 	} else if c < 0 {
 		return false, fmt.Errorf("cannot upgrade to a lower version. Found given target version %q, current cluster version %q", clusterMeta.Version, currentEKSVersion)
 	}

pkg/utils/utils.go

@@ -37,7 +37,7 @@ func IsMinVersion(minimumVersion, version string) (bool, error) {
 	}
 	targetVersion, err := semver.ParseTolerant(version)
 	if err != nil {
-		return false, fmt.Errorf("unable to parse version %s", version)
+		return false, fmt.Errorf("unable to parse target version %s", version)
 	}
 	return targetVersion.GE(minVersion), nil
 }
@@ -49,11 +49,11 @@ func IsMinVersion(minimumVersion, version string) (bool, error) {
 func CompareVersions(a, b string) (int, error) {
 	aVersion, err := semver.ParseTolerant(a)
 	if err != nil {
-		return 0, errors.Wrapf(err, "unable to parse version %q", a)
+		return 0, errors.Wrapf(err, "unable to parse first version %q", a)
 	}
 	bVersion, err := semver.ParseTolerant(b)
 	if err != nil {
-		return 0, errors.Wrapf(err, "unable to parse version %q", b)
+		return 0, errors.Wrapf(err, "unable to parse second version %q", b)
 	}
 	return aVersion.Compare(bVersion), nil
 }