feat: add functionality to install kubectl

internal/kubectl/install.go

@@ -0,0 +1,44 @@
+package kubectl
+
+import (
+	"fmt"
+	"io"
+	"net/http"
+	"os"
+	"runtime"
+)
+
+const (
+	kubectlBase = "https://storage.googleapis.com"
+	pathBase    = "/kubernetes-release/releases/%s/bin/%s/%s/kubectl"
+	kubectlPath = "./kubectl"
+)
+
+// Install installs the desired version of kubectl
+func Install(version string) error {
+	path := fmt.Sprintf(pathBase, version, runtime.GOOS, runtime.GOARCH)
+	url := fmt.Sprintf("%s%s", kubectlBase, path)
+	res, err := http.Get(url)
+	if err != nil {
+		return err
+	}
+	defer res.Body.Close()
+	if res.StatusCode != http.StatusOK {
+		return fmt.Errorf("could not install kubectl, received code %d", res.StatusCode)
+	}
+	f, err := os.Create(kubectlPath)
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+	_, err = io.Copy(f, res.Body)
+	if err != nil {
+		return err
+	}
+	return os.Chmod(kubectlPath, os.ModePerm)
+}
+
+// Uninstall deletes the installed binary
+func Uninstall() error {
+	return os.RemoveAll(kubectlPath)
+}

internal/kubectl/kubectl_test.go

@@ -0,0 +1,66 @@
+package kubectl
+
+import (
+	"fmt"
+	"io/ioutil"
+	"net/http"
+	"os"
+	"runtime"
+	"testing"
+
+	"github.com/stretchr/testify/suite"
+	"gopkg.in/h2non/gock.v1"
+)
+
+const (
+	testVersion = "v1.13.2"
+	testBinary  = "kubectl binary"
+)
+
+type KubectlTestSuite struct {
+	suite.Suite
+}
+
+func (suite *KubectlTestSuite) TearDownTest() {
+	require := suite.Require()
+
+	err := Uninstall()
+	require.NoError(err)
+}
+
+func (suite *KubectlTestSuite) TestInstall() {
+	assert := suite.Assert()
+	require := suite.Require()
+
+	path := fmt.Sprintf(pathBase, testVersion, runtime.GOOS, runtime.GOARCH)
+	gock.New(kubectlBase).
+		Get(path).
+		Reply(http.StatusOK).
+		BodyString(testBinary)
+
+	err := Install(testVersion)
+	require.NoError(err)
+	f, err := os.Open(kubectlPath)
+	require.NoError(err)
+	b, err := ioutil.ReadAll(f)
+	require.NoError(err)
+	assert.EqualValues(testBinary, b)
+}
+
+func (suite *KubectlTestSuite) TestInstallBadResponse() {
+	require := suite.Require()
+
+	path := fmt.Sprintf(pathBase, testVersion, runtime.GOOS, runtime.GOARCH)
+	gock.New(kubectlBase).
+		Get(path).
+		Reply(http.StatusInternalServerError).
+		BodyString(testBinary)
+
+	err := Install(testVersion)
+	require.EqualError(err, "could not install kubectl, received code 500")
+}
+
+func TestKubectlTestSuite(t *testing.T) {
+	tests := new(KubectlTestSuite)
+	suite.Run(t, tests)
+}