fix: --server-dry-run was deprecated in kubectl 1.18

internal/app/cli.go

@@ -154,7 +154,7 @@ func (c *cli) parse() {
 		log.Fatal("this version of Helmsman does not work with helm releases older than 3.0.0")
 	}
 
-	kubectlVersion := strings.TrimSpace(strings.SplitN(getKubectlClientVersion(), ": ", 2)[1])
+	kubectlVersion := getKubectlVersion()
 	log.Verbose("kubectl client version: " + kubectlVersion)
 
 	if len(c.files) == 0 {

internal/app/helm_helpers.go

@@ -69,32 +69,22 @@ func getChartInfo(chartName, chartVersion string) (*chartInfo, error) {
 
 // getHelmClientVersion returns Helm client Version
 func getHelmVersion() string {
-	cmd := helmCmd([]string{"version", "--short", "-c"}, "Checking Helm version")
+	cmd := helmCmd([]string{"version", "--short", "--client"}, "Checking Helm version")
 
 	res, err := cmd.Exec()
 	if err != nil {
 		log.Fatalf("While checking helm version: %v", err)
 	}
 
-	return res.output
+	version := strings.TrimSpace(res.output)
+	if !strings.HasPrefix(version, "v") {
+		version = strings.SplitN(version, ":", 2)[1]
+	}
+	return version
 }
 
 func checkHelmVersion(constraint string) bool {
-	helmVersion := strings.TrimSpace(getHelmVersion())
-	extractedHelmVersion := helmVersion
-	if !strings.HasPrefix(helmVersion, "v") {
-		extractedHelmVersion = strings.TrimSpace(strings.Split(helmVersion, ":")[1])
-	}
-	v, err := semver.NewVersion(extractedHelmVersion)
-	if err != nil {
-		return false
-	}
-
-	jsonConstraint, err := semver.NewConstraint(constraint)
-	if err != nil {
-		return false
-	}
-	return jsonConstraint.Check(v)
+	return checkVersion(getHelmVersion(), constraint)
 }
 
 // helmPluginExists returns true if the plugin is present in the environment and false otherwise.

internal/app/kube_helpers.go

@@ -312,26 +312,44 @@ func getReleaseContext(releaseName, namespace, storageBackend string) string {
 	return rctx
 }
 
-// getKubectlClientVersion returns kubectl client version
-func getKubectlClientVersion() string {
-	cmd := kubectl([]string{"version", "--client", "--short"}, "Checking kubectl version")
+// getKubectlVersion returns kubectl client version
+func getKubectlVersion() string {
+	cmd := kubectl([]string{"version", "--short", "--client"}, "Checking kubectl version")
 
 	res, err := cmd.Exec()
 	if err != nil {
 		log.Fatalf("While checking kubectl version: %v", err)
 	}
-	return res.output
+	version := strings.TrimSpace(res.output)
+	if !strings.HasPrefix(version, "v") {
+		version = strings.SplitN(version, ":", 2)[1]
+	}
+	return version
+}
+
+func checkKubectlVersion(constraint string) bool {
+	return checkVersion(getKubectlVersion(), constraint)
 }
 
 // getKubeDryRunFlag returns kubectl dry-run flag if helmsman --dry-run flag is enabled
+// TODO: this should be cleanup once 1.18 is old enough
 func (c *cli) getKubeDryRunFlag(action string) string {
+	var flag string
 	if c.dryRun {
+		flag = "--dry-run"
+		recent := checkKubectlVersion(">=v1.18.0")
 		switch action {
 		case "apply":
-			return "--server-dry-run"
+			if recent {
+				flag += "=server"
+			} else {
+				flag = "--server-dry-run"
+			}
 		default:
-			return "--dry-run"
+			if recent {
+				flag += "=client"
+			}
 		}
 	}
-	return ""
+	return flag
 }

internal/app/utils.go

@@ -16,6 +16,7 @@ import (
 	"strings"
 	"time"
 
+	"github.com/Masterminds/semver"
 	"github.com/Praqma/helmsman/internal/aws"
 	"github.com/Praqma/helmsman/internal/azure"
 	"github.com/Praqma/helmsman/internal/gcs"
@@ -468,6 +469,19 @@ func isValidFile(filePath string, allowedFileTypes []string) error {
 	return nil
 }
 
+func checkVersion(version, constraint string) bool {
+	v, err := semver.NewVersion(version)
+	if err != nil {
+		return false
+	}
+
+	jsonConstraint, err := semver.NewConstraint(constraint)
+	if err != nil {
+		return false
+	}
+	return jsonConstraint.Check(v)
+}
+
 // notify MSTeams sends a JSON formatted message to MSTeams channel over a webhook url
 // It takes the content of the message (what changes helmsman is going to do or have done separated by \n)
 // and the webhook URL as well as a flag specifying if this is a failure message or not