Add support for kubernetes host detection (#4514)

Additionally improve what we print for `docker pull`
such that its precisely the relevant release tag.

Fixes #4456

cmd/update-main.go

@@ -107,7 +107,8 @@ func isDocker(cgroupFile string) (bool, error) {
 	return bytes.Contains(cgroup, []byte("docker")), err
 }
 
-// IsDocker - returns if the environment is docker or not.
+// IsDocker - returns if the environment minio is running
+// is docker or not.
 func IsDocker() bool {
 	found, err := isDocker("/proc/self/cgroup")
 	fatalIf(err, "Error in docker check.")
@@ -115,6 +116,16 @@ func IsDocker() bool {
 	return found
 }
 
+// IsKubernetes returns if the environment minio is
+// running is kubernetes or not.
+func IsKubernetes() bool {
+	// Kubernetes env used to validate if we are
+	// indeed running inside a kubernetes pod
+	// is KUBERNETES_SERVICE_HOST but in future
+	// we might need to enhance this.
+	return os.Getenv("KUBERNETES_SERVICE_HOST") != ""
+}
+
 func isSourceBuild(minioVersion string) bool {
 	_, err := time.Parse(time.RFC3339, minioVersion)
 	return err != nil
@@ -127,7 +138,8 @@ func IsSourceBuild() bool {
 
 // DO NOT CHANGE USER AGENT STYLE.
 // The style should be
-//   Minio (<OS>; <ARCH>[; docker][; source])  Minio/<VERSION> Minio/<RELEASE-TAG> Minio/<COMMIT-ID>
+//
+//   Minio (<OS>; <ARCH>[; kubernetes][; docker][; source]) Minio/<VERSION> Minio/<RELEASE-TAG> Minio/<COMMIT-ID>
 //
 // For any change here should be discussed by openning an issue at https://github.com/minio/minio/issues.
 func getUserAgent(mode string) string {
@@ -135,6 +147,9 @@ func getUserAgent(mode string) string {
 	if mode != "" {
 		userAgent += "; " + mode
 	}
+	if IsKubernetes() {
+		userAgent += "; kubernetes"
+	}
 	if IsDocker() {
 		userAgent += "; docker"
 	}
@@ -226,11 +241,24 @@ func getLatestReleaseTime(timeout time.Duration, mode string) (releaseTime time.
 	return parseReleaseData(data)
 }
 
-func getDownloadURL() (downloadURL string) {
+// Kubernetes deploy doc link.
+const kubernetesDeploymentDoc = "https://docs.minio.io/docs/deploy-minio-on-kubernetes"
+
+func getDownloadURL(buildDate time.Time) (downloadURL string) {
+	// Check if we are in kubernetes environment, return
+	// deployment guide for update procedures.
+	if IsKubernetes() {
+		return kubernetesDeploymentDoc
+	}
+
+	// Check if we are docker environment, return docker update command
 	if IsDocker() {
-		return "docker pull minio/minio"
+		// Construct release tag name.
+		rTag := "RELEASE." + buildDate.Format(minioReleaseTagTimeLayout)
+		return fmt.Sprintf("docker pull minio/minio:%s", rTag)
 	}
 
+	// For binary only installations, then we just show binary download link.
 	if runtime.GOOS == "windows" {
 		return minioReleaseURL + "minio.exe"
 	}
@@ -254,7 +282,7 @@ func getUpdateInfo(timeout time.Duration, mode string) (older time.Duration,
 
 	if latestReleaseTime.After(currentReleaseTime) {
 		older = latestReleaseTime.Sub(currentReleaseTime)
-		downloadURL = getDownloadURL()
+		downloadURL = getDownloadURL(latestReleaseTime)
 	}
 
 	return older, downloadURL, nil

cmd/update-main_test.go

@@ -30,6 +30,28 @@ import (
 	"time"
 )
 
+func TestDownloadURL(t *testing.T) {
+	minioVersion1 := UTCNow()
+	durl := getDownloadURL(minioVersion1)
+	if runtime.GOOS == "windows" {
+		if durl != minioReleaseURL+"minio.exe" {
+			t.Errorf("Expected %s, got %s", minioReleaseURL+"minio.exe", durl)
+		}
+	} else {
+		if durl != minioReleaseURL+"minio" {
+			t.Errorf("Expected %s, got %s", minioReleaseURL+"minio", durl)
+		}
+	}
+
+	os.Setenv("KUBERNETES_SERVICE_HOST", "10.11.148.5")
+	defer os.Unsetenv("KUBERNETES_SERVICE_HOST")
+
+	durl = getDownloadURL(minioVersion1)
+	if durl != kubernetesDeploymentDoc {
+		t.Errorf("Expected %s, got %s", kubernetesDeploymentDoc, durl)
+	}
+}
+
 func TestGetCurrentReleaseTime(t *testing.T) {
 	minioVersion1 := UTCNow().Format(time.RFC3339)
 	releaseTime1, _ := time.Parse(time.RFC3339, minioVersion1)
@@ -136,6 +158,21 @@ func TestGetCurrentReleaseTime(t *testing.T) {
 	}
 }
 
+// Tests if the environment we are running is in kubernetes.
+func TestIsKubernetes(t *testing.T) {
+	os.Setenv("KUBERNETES_SERVICE_HOST", "10.11.148.5")
+	kubernetes := IsKubernetes()
+	if !kubernetes {
+		t.Fatalf("Expected %t, got %t", true, kubernetes)
+	}
+	os.Unsetenv("KUBERNETES_SERVICE_HOST")
+	kubernetes = IsKubernetes()
+	if kubernetes {
+		t.Fatalf("Expected %t, got %t", false, kubernetes)
+	}
+}
+
+// Tests if the environment we are running is in docker.
 func TestIsDocker(t *testing.T) {
 	createTempFile := func(content string) string {
 		tmpfile, err := ioutil.TempFile("", "isdocker-testcase")
@@ -164,6 +201,7 @@ func TestIsDocker(t *testing.T) {
 1:name=systemd:/user.slice/user-1000.slice/user@1000.service/gnome-terminal-server.service
 `)
 	defer os.Remove(filename1)
+
 	filename2 := createTempFile(`14:name=systemd:/docker/d5eb950884d828237f60f624ff575a1a7a4daa28a8d4d750040527ed9545e727
 13:pids:/docker/d5eb950884d828237f60f624ff575a1a7a4daa28a8d4d750040527ed9545e727
 12:hugetlb:/docker/d5eb950884d828237f60f624ff575a1a7a4daa28a8d4d750040527ed9545e727