Merge pull request kubernetes#1138 from mcastellin/nodekiller-provide…

…r-decouple

Decouple SSH command execution in util.SSH to enable unit testing

.gitignore

@@ -31,3 +31,6 @@ clusterloader2/clusterloader
 
 # Vscode files
 .vscode
+
+# GoLand files
+.idea

clusterloader2/pkg/chaos/nodes.go

@@ -49,6 +49,7 @@ type NodeKiller struct {
 	// killedNodes stores names of the nodes that have been killed by NodeKiller.
 	killedNodes sets.String
 	recorder    *eventRecorder
+	ssh         util.SSHExecutor
 }
 
 type nodeAction string
@@ -85,7 +86,8 @@ func NewNodeKiller(config api.NodeFailureConfig, client clientset.Interface, pro
 	if provider != "gce" && provider != "gke" {
 		return nil, fmt.Errorf("provider %q is not supported by NodeKiller", provider)
 	}
-	return &NodeKiller{config, client, provider, sets.NewString(), newEventRecorder()}, nil
+	sshExecutor := &util.GCloudSSHExecutor{}
+	return &NodeKiller{config, client, provider, sets.NewString(), newEventRecorder(), sshExecutor}, nil
 }
 
 // Run starts NodeKiller until stopCh is closed.
@@ -154,7 +156,7 @@ func (k *NodeKiller) kill(nodes []v1.Node, stopCh <-chan struct{}) {
 
 			klog.Infof("%s: Stopping docker and kubelet on %q to simulate failure", k, node.Name)
 			k.addStopServicesEvent(node.Name)
-			err := util.SSH("sudo systemctl stop docker kubelet", &node, nil)
+			err := k.ssh.Exec("sudo systemctl stop docker kubelet", &node, nil)
 			if err != nil {
 				klog.Errorf("%s: ERROR while stopping node %q: %v", k, node.Name, err)
 				return
@@ -165,7 +167,7 @@ func (k *NodeKiller) kill(nodes []v1.Node, stopCh <-chan struct{}) {
 
 			klog.Infof("%s: Rebooting %q to repair the node", k, node.Name)
 			k.addRebootEvent(node.Name)
-			err = util.SSH("sudo reboot", &node, nil)
+			err = k.ssh.Exec("sudo reboot", &node, nil)
 			if err != nil {
 				klog.Errorf("%s: Error while rebooting node %q: %v", k, node.Name, err)
 				return

clusterloader2/pkg/prometheus/prometheus.go

@@ -73,6 +73,8 @@ type PrometheusController struct {
 	templateMapping map[string]interface{}
 	// diskMetadata store name and zone of Prometheus persistent disk.
 	diskMetadata prometheusDiskMetadata
+	// ssh executor to run commands in cluster nodes via ssh
+	ssh util.SSHExecutor
 }
 
 // NewPrometheusController creates a new instance of PrometheusController for the given config.
@@ -121,6 +123,8 @@ func NewPrometheusController(clusterLoaderConfig *config.ClusterLoaderConfig) (p
 
 	pc.templateMapping = mapping
 
+	pc.ssh = &util.GCloudSSHExecutor{}
+
 	return pc, nil
 }
 
@@ -267,7 +271,7 @@ func (pc *PrometheusController) runNodeExporter() error {
 					return fmt.Errorf("Unable to open manifest file: %v", err)
 				}
 				defer f.Close()
-				return util.SSH("sudo tee /etc/kubernetes/manifests/node-exporter.yaml > /dev/null", &node, f)
+				return pc.ssh.Exec("sudo tee /etc/kubernetes/manifests/node-exporter.yaml > /dev/null", &node, f)
 			})
 		}
 	}

clusterloader2/pkg/util/ssh.go

@@ -25,9 +25,17 @@ import (
 	"k8s.io/klog"
 )
 
+// SSHExecutor interface can run commands in cluster nodes via SSH
+type SSHExecutor interface {
+	Exec(command string, node *v1.Node, stdin io.Reader) error
+}
+
+// GCloudSSHExecutor runs commands in GCloud cluster nodes
+type GCloudSSHExecutor struct{}
+
 // SSH executes command on a given node with stdin provided.
 // If stdin is nil, the process reads from null device.
-func SSH(command string, node *v1.Node, stdin io.Reader) error {
+func (e *GCloudSSHExecutor) Exec(command string, node *v1.Node, stdin io.Reader) error {
 	zone, ok := node.Labels["failure-domain.beta.kubernetes.io/zone"]
 	if !ok {
 		return fmt.Errorf("unknown zone for %q node: no failure-domain.beta.kubernetes.io/zone label", node.Name)