seperation of network calls when getting version

updated the network calls to be package local so tests could pass their
own implementation. A public interface was not provided as it would not
be likely this would ever be needed or wanted.

cmd/kubeadm/app/util/version.go

@@ -62,6 +62,10 @@ var (
 //  latest-1    (latest release in 1.x, including alpha/beta)
 //  latest-1.0  (and similarly 1.1, 1.2, 1.3, ...)
 func KubernetesReleaseVersion(version string) (string, error) {
+	return kubernetesReleaseVersion(version, fetchFromURL)
+}
+
+func kubernetesReleaseVersion(version string, fetcher func(string, time.Duration) (string, error)) (string, error) {
 	ver := normalizedBuildVersion(version)
 	if len(ver) != 0 {
 		return ver, nil
@@ -87,7 +91,7 @@ func KubernetesReleaseVersion(version string) (string, error) {
 		clientVersion, clientVersionErr := kubeadmVersion(pkgversion.Get().String())
 		// Fetch version from the internet.
 		url := fmt.Sprintf("%s/%s.txt", bucketURL, versionLabel)
-		body, err := fetchFromURL(url, getReleaseVersionTimeout)
+		body, err := fetcher(url, getReleaseVersionTimeout)
 		if err != nil {
 			// If the network operaton was successful but the server did not reply with StatusOK
 			if body != "" {
@@ -97,18 +101,18 @@ func KubernetesReleaseVersion(version string) (string, error) {
 				// Handle air-gapped environments by falling back to the client version.
 				klog.Warningf("could not fetch a Kubernetes version from the internet: %v", err)
 				klog.Warningf("falling back to the local client version: %s", clientVersion)
-				return KubernetesReleaseVersion(clientVersion)
+				return kubernetesReleaseVersion(clientVersion, fetcher)
 			}
 		}
 
 		if clientVersionErr != nil {
 			if err != nil {
 				klog.Warningf("could not obtain neither client nor remote version; fall back to: %s", constants.CurrentKubernetesVersion)
-				return KubernetesReleaseVersion(constants.CurrentKubernetesVersion.String())
+				return kubernetesReleaseVersion(constants.CurrentKubernetesVersion.String(), fetcher)
 			}
 
 			klog.Warningf("could not obtain client version; using remote version: %s", body)
-			return KubernetesReleaseVersion(body)
+			return kubernetesReleaseVersion(body, fetcher)
 		}
 
 		// both the client and the remote version are obtained; validate them and pick a stable version
@@ -117,7 +121,7 @@ func KubernetesReleaseVersion(version string) (string, error) {
 			return "", err
 		}
 		// Re-validate received version and return.
-		return KubernetesReleaseVersion(body)
+		return kubernetesReleaseVersion(body, fetcher)
 	}
 	return "", errors.Errorf("version %q doesn't match patterns for neither semantic version nor labels (stable, latest, ...)", version)
 }

cmd/kubeadm/app/util/version_test.go

@@ -17,12 +17,13 @@ limitations under the License.
 package util
 
 import (
+	"errors"
 	"fmt"
 	"net/http"
-	"net/http/httptest"
 	"path"
 	"strings"
 	"testing"
+	"time"
 )
 
 func TestEmptyVersion(t *testing.T) {
@@ -50,7 +51,10 @@ func TestValidVersion(t *testing.T) {
 	}
 	for _, s := range validVersions {
 		t.Run(s, func(t *testing.T) {
-			ver, err := KubernetesReleaseVersion(s)
+			fileFetcher := func(url string, timeout time.Duration) (string, error) {
+				return "", errors.New("Should not make internet call")
+			}
+			ver, err := kubernetesReleaseVersion(s, fileFetcher)
 			t.Log("Valid: ", s, ver, err)
 			if err != nil {
 				t.Errorf("KubernetesReleaseVersion unexpected error for version %q: %v", s, err)
@@ -72,7 +76,10 @@ func TestInvalidVersion(t *testing.T) {
 	}
 	for _, s := range invalidVersions {
 		t.Run(s, func(t *testing.T) {
-			ver, err := KubernetesReleaseVersion(s)
+			fileFetcher := func(url string, timeout time.Duration) (string, error) {
+				return "", errors.New("Should not make internet call")
+			}
+			ver, err := kubernetesReleaseVersion(s, fileFetcher)
 			t.Log("Invalid: ", s, ver, err)
 			if err == nil {
 				t.Errorf("KubernetesReleaseVersion error expected for version %q, but returned successfully", s)
@@ -92,7 +99,10 @@ func TestValidConvenientForUserVersion(t *testing.T) {
 	}
 	for _, s := range validVersions {
 		t.Run(s, func(t *testing.T) {
-			ver, err := KubernetesReleaseVersion(s)
+			fileFetcher := func(url string, timeout time.Duration) (string, error) {
+				return "", errors.New("Should not make internet call")
+			}
+			ver, err := kubernetesReleaseVersion(s, fileFetcher)
 			t.Log("Valid: ", s, ver, err)
 			if err != nil {
 				t.Errorf("KubernetesReleaseVersion unexpected error for version %q: %v", s, err)
@@ -121,22 +131,19 @@ func TestVersionFromNetwork(t *testing.T) {
 		"garbage":    {"<?xml version='1.0'?><Error><Code>NoSuchKey</Code><Message>The specified key does not exist.</Message></Error>", http.StatusOK, "", true},
 		"unknown":    {"The requested URL was not found on this server.", http.StatusNotFound, "", true},
 	}
-	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+
-		key := strings.TrimSuffix(path.Base(r.URL.Path), ".txt")
+	fileFetcher := func(url string, timeout time.Duration) (string, error) {
+		key := strings.TrimSuffix(path.Base(url), ".txt")
 		res, found := cases[key]
 		if found {
-			http.Error(w, res.Content, res.Status)
+			return res.Content, nil
-		} else {
-			http.Error(w, "Unknown test case key!", http.StatusNotFound)
 		}
-	}))
+		return "Unknown test case key!", errors.New("unknown test case key")
-	defer server.Close()
+	}
-
-	kubeReleaseBucketURL = server.URL
 
 	for k, v := range cases {
 		t.Run(k, func(t *testing.T) {
-			ver, err := KubernetesReleaseVersion(k)
+			ver, err := kubernetesReleaseVersion(k, fileFetcher)
 			t.Logf("Key: %q. Result: %q, Error: %v", k, ver, err)
 			switch {
 			case err != nil && !v.ErrorExpected:
@@ -272,7 +279,15 @@ func TestCIBuildVersion(t *testing.T) {
 
 	for _, tc := range cases {
 		t.Run(fmt.Sprintf("input:%s/expected:%s", tc.input, tc.expected), func(t *testing.T) {
-			ver, err := KubernetesReleaseVersion(tc.input)
+
+			fileFetcher := func(url string, timeout time.Duration) (string, error) {
+				if tc.valid {
+					return tc.expected, nil
+				}
+				return "Unknown test case key!", fmt.Errorf("unknown test case key")
+			}
+
+			ver, err := kubernetesReleaseVersion(tc.input, fileFetcher)
 			t.Logf("Input: %q. Result: %q, Error: %v", tc.input, ver, err)
 			switch {
 			case err != nil && tc.valid: