consistent requirement checks (#29)

- consistent requirement checks and some cleanup
- Adjusted requirement checks to use spinner logs for warnings
- Adjusted minikube version warning to include the version numbers as it was hard to guess which version es recommended
- Moved kubectl helper file into dedicated package
- Used verbose flag for kubectl and minikube commands
- Moved gliph in spinner message to start of line
- introduced new gliphs for spinner
- Have a better vmdriver default for windows
- Using simple spinner only for windows

internal/kubectl/kubectl.go

@@ -0,0 +1,205 @@
+package kubectl
+
+import (
+	"bufio"
+	"bytes"
+	"fmt"
+	"os/exec"
+	"regexp"
+	"strings"
+	"time"
+
+	"github.com/Masterminds/semver"
+	yaml "gopkg.in/yaml.v2"
+)
+
+const (
+	kubectlVersion string = "1.11.0"
+	sleep                 = 5 * time.Second
+)
+
+//RunCmd executes a kubectl command with given arguments
+func RunCmd(verbose bool, args ...string) (string, error) {
+	cmd := exec.Command("kubectl", args[0:]...)
+	return execCmd(cmd, strings.Join(args, " "), verbose)
+}
+
+//RunApplyCmd executes a kubectl apply command with given resources
+func RunApplyCmd(resources []map[string]interface{}, verbose bool) (string, error) {
+	cmd := exec.Command("kubectl", "apply", "-f", "-")
+	buf := &bytes.Buffer{}
+	enc := yaml.NewEncoder(buf)
+	for _, y := range resources {
+		err := enc.Encode(y)
+		if err != nil {
+			return "", err
+		}
+	}
+	err := enc.Close()
+	if err != nil {
+		return "", err
+	}
+	cmd.Stdin = buf
+	return execCmd(cmd, fmt.Sprintf("apply -f -%s", resources), verbose)
+}
+
+func execCmd(cmd *exec.Cmd, inputText string, verbose bool) (string, error) {
+	out, err := cmd.CombinedOutput()
+	unquotedOut := strings.Replace(string(out), "'", "", -1)
+	if err != nil {
+		if verbose {
+			fmt.Printf("\nExecuted command:\n  kubectl %s\nwith output:\n  %s\nand error:\n  %s\n", inputText, string(out), err)
+		}
+		return unquotedOut, fmt.Errorf("Failed executing kubectl command 'kubectl %s' with output '%s' and error message '%s'", inputText, out, err)
+	}
+	if verbose {
+		fmt.Printf("\nExecuted command:\n  kubectl %s\nwith output:\n  %s\n", inputText, string(out))
+	}
+	return unquotedOut, nil
+}
+
+//WaitForPodReady waits till a pod is deployed and has status 'running'.
+// The pod gets identified by the namespace and a lebel key=value pair.
+func WaitForPodReady(namespace string, labelName string, labelValue string, verbose bool) error {
+	for {
+		isDeployed, err := IsPodDeployed(namespace, labelName, labelValue, verbose)
+		if err != nil {
+			return err
+		}
+		if isDeployed {
+			break
+		}
+		time.Sleep(sleep)
+	}
+
+	for {
+		isReady, err := IsPodReady(namespace, labelName, labelValue, verbose)
+		if err != nil {
+			return err
+		}
+		if isReady {
+			break
+		}
+		time.Sleep(sleep)
+	}
+	return nil
+}
+
+//WaitForPodGone waits till a pod is not existent anymore.
+// The pod gets identified by the namespace and a lebel key=value pair.
+func WaitForPodGone(namespace string, labelName string, labelValue string, verbose bool) error {
+	for {
+		check, err := IsPodDeployed(namespace, labelName, labelValue, verbose)
+		if err != nil {
+			return err
+		}
+		if !check {
+			break
+		}
+		time.Sleep(sleep)
+	}
+	return nil
+}
+
+//IsPodDeployed checks if a pod is deployed.
+// It will not wait till it is deployed.
+// The pod gets identified by the namespace and a label key=value pair.
+func IsPodDeployed(namespace string, labelName string, labelValue string, verbose bool) (bool, error) {
+	return IsResourceDeployed("pod", namespace, labelName, labelValue, verbose)
+}
+
+//IsResourceDeployed checks if a kubernetes resource is deployed.
+// It will not wait till it is deployed.
+// The resource gets identified by the namespace and a lebel key=value pair.
+func IsResourceDeployed(resource string, namespace string, labelName string, labelValue string, verbose bool) (bool, error) {
+	resourceNames, err := RunCmd(verbose, "get", resource, "-n", namespace, "-l", labelName+"="+labelValue, "-o", "jsonpath='{.items[*].metadata.name}'")
+	if err != nil {
+		return false, err
+	}
+	if resourceNames == "" {
+		return false, nil
+	}
+	return true, nil
+}
+
+//IsClusterResourceDeployed checks if a kubernetes cluster resource is deployed.
+// It will not wait till it is deployed.
+// The resource gets identified by a lebel key=value pair.
+func IsClusterResourceDeployed(resource string, labelName string, labelValue string, verbose bool) (bool, error) {
+	resourceNames, err := RunCmd(verbose, "get", resource, "-l", labelName+"="+labelValue, "-o", "jsonpath='{.items[*].metadata.name}'")
+	if err != nil {
+		return false, err
+	}
+	if resourceNames == "" {
+		return false, nil
+	}
+	return true, nil
+}
+
+//IsPodReady checks if a pod is deployed and running.
+// It will not wait till it is deployed or running.
+// The pod gets identified by the namespace and a lebel key=value pair.
+func IsPodReady(namespace string, labelName string, labelValue string, verbose bool) (bool, error) {
+	podNames, err := RunCmd(verbose, "get", "pods", "-n", namespace, "-l", labelName+"="+labelValue, "-o", "jsonpath='{.items[*].metadata.name}'")
+	if err != nil {
+		return false, err
+	}
+
+	if podNames == "" {
+		return false, nil
+	}
+
+	scanner := bufio.NewScanner(strings.NewReader(podNames))
+	scanner.Split(bufio.ScanWords)
+	for scanner.Scan() {
+		if err := scanner.Err(); err != nil {
+			return false, err
+		}
+
+		pod := scanner.Text()
+		containerStatus, err := RunCmd(verbose, "get", "pod", pod, "-n", namespace, "-o", "jsonpath='{.status.containerStatuses[0].ready}'")
+		if err != nil {
+			return false, err
+		}
+
+		if containerStatus != "true" {
+			events, err := RunCmd(verbose, "get", "event", "-n", namespace, "-o", "go-template='{{range .items}}{{if eq .involvedObject.name \"'"+pod+"'\"}}{{.message}}{{\"\\n\"}}{{end}}{{end}}'")
+			if err != nil {
+				fmt.Printf("Error while checking for pod events '%s'\n‚", err)
+			}
+			if events != "" {
+				fmt.Printf("Status '%s'", events)
+			}
+			return false, nil
+		}
+	}
+	return true, nil
+}
+
+//CheckVersion assures that the kubectl version used is compatible
+func CheckVersion(verbose bool) (string, error) {
+	versionText, err := RunCmd(verbose, "version", "--client", "--short")
+	if err != nil {
+		return "", err
+	}
+
+	exp, _ := regexp.Compile("Client Version: v(.*)")
+	versionString := exp.FindStringSubmatch(versionText)
+	version, err := semver.NewVersion(versionString[1])
+	if err != nil {
+		return "", err
+	}
+
+	constraintString := "~" + kubectlVersion
+	constraint, err := semver.NewConstraint(constraintString)
+	if err != nil {
+		return "", err
+	}
+
+	check := constraint.Check(version)
+	if check {
+		return "", nil
+	}
+
+	return fmt.Sprintf("You are using an unsupported kubectl version '%s'. This may not work. It is recommended to use kubectl version '%s'", version, kubectlVersion), nil
+}