honor kubernetes_version setting

util/util.go

@@ -7,6 +7,7 @@ import (
 	"strings"
 
 	"github.com/coreos/go-semver/semver"
+	"github.com/rancher/types/apis/management.cattle.io/v3"
 )
 
 const (
@@ -63,3 +64,47 @@ func IsSymlink(file string) (bool, error) {
 	}
 	return false, nil
 }
+
+// ValidateVersion - Return error if version is not valid
+// Is version major.minor >= oldest major.minor supported
+// Is version in the AllK8sVersions list
+// Is version not in the "bad" list
+func ValidateVersion(version string) error {
+	// Create target version and current versions list
+	targetVersion, err := StrToSemVer(version)
+	if err != nil {
+		return fmt.Errorf("%s is not valid semver", version)
+	}
+	currentVersionsList := []*semver.Version{}
+	for _, ver := range v3.K8sVersionsCurrent {
+		v, err := StrToSemVer(ver)
+		if err != nil {
+			return fmt.Errorf("%s in Current Versions list is not valid semver", ver)
+		}
+
+		currentVersionsList = append(currentVersionsList, v)
+	}
+
+	// Make sure Target version is greater than or equal to oldest major.minor supported.
+	semver.Sort(currentVersionsList)
+	if targetVersion.Major < currentVersionsList[0].Major {
+		return fmt.Errorf("%s is an unsupported Kubernetes version - see 'rke config --system-images --all' for versions supported with this release", version)
+	}
+	if targetVersion.Major == currentVersionsList[0].Major {
+		if targetVersion.Minor < currentVersionsList[0].Minor {
+			return fmt.Errorf("%s is an unsupported Kubernetes version - see 'rke config --system-images --all' for versions supported with this release", version)
+		}
+	}
+	// Make sure Target version is in the AllK8sVersions list.
+	_, ok := v3.AllK8sVersions[version]
+	if !ok {
+		return fmt.Errorf("%s is an unsupported Kubernetes version - see 'rke config --system-images --all' for versions supported with this release", version)
+	}
+	// Make sure Target version is not "bad".
+	_, ok = v3.K8sBadVersions[version]
+	if ok {
+		return fmt.Errorf("%s is an unsupported Kubernetes version - see 'rke config --system-images --all' for versions supported with this release", version)
+	}
+
+	return nil
+}