versioning: adds tooling to compile a program against a given old CNI version

Allows us to write tests that cover interactions between components of
differing versions

pkg/version/testhelpers/testhelpers.go

@@ -0,0 +1,156 @@
+// Copyright 2016 CNI authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package testhelpers supports testing of CNI components of different versions
+//
+// For example, to build a plugin against an old version of the CNI library,
+// we can pass the plugin's source and the old git commit reference to BuildAt.
+// We could then test how the built binary responds when called by the latest
+// version of this library.
+package testhelpers
+
+import (
+	"fmt"
+	"io/ioutil"
+	"math/rand"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"strings"
+	"time"
+)
+
+const packageBaseName = "github.com/containernetworking/cni"
+
+func run(cmd *exec.Cmd) error {
+	out, err := cmd.CombinedOutput()
+	if err != nil {
+		command := strings.Join(cmd.Args, " ")
+		return fmt.Errorf("running %q: %s", command, out)
+	}
+	return nil
+}
+
+func goBuildEnviron(gopath string) []string {
+	environ := os.Environ()
+	for i, kvp := range environ {
+		if strings.HasPrefix(kvp, "GOPATH=") {
+			environ[i] = "GOPATH=" + gopath
+			return environ
+		}
+	}
+	environ = append(environ, "GOPATH="+gopath)
+	return environ
+}
+
+func buildGoProgram(gopath, packageName, outputFilePath string) error {
+	cmd := exec.Command("go", "build", "-o", outputFilePath, packageName)
+	cmd.Env = goBuildEnviron(gopath)
+	return run(cmd)
+}
+
+func createSingleFilePackage(gopath, packageName string, fileContents []byte) error {
+	dirName := filepath.Join(gopath, "src", packageName)
+	err := os.MkdirAll(dirName, 0700)
+	if err != nil {
+		return err
+	}
+
+	return ioutil.WriteFile(filepath.Join(dirName, "main.go"), fileContents, 0600)
+}
+
+func removePackage(gopath, packageName string) error {
+	dirName := filepath.Join(gopath, "src", packageName)
+	return os.RemoveAll(dirName)
+}
+
+func isRepoRoot(path string) bool {
+	_, err := ioutil.ReadDir(filepath.Join(path, ".git"))
+	return (err == nil) && (filepath.Base(path) == "cni")
+}
+
+func LocateCurrentGitRepo() (string, error) {
+	dir, err := os.Getwd()
+	if err != nil {
+		return "", err
+	}
+
+	for i := 0; i < 5; i++ {
+		if isRepoRoot(dir) {
+			return dir, nil
+		}
+
+		dir, err = filepath.Abs(filepath.Dir(dir))
+		if err != nil {
+			return "", fmt.Errorf("abs(dir(%q)): %s", dir, err)
+		}
+	}
+
+	return "", fmt.Errorf("unable to find cni repo root, landed at %q", dir)
+}
+
+func gitCloneThisRepo(cloneDestination string) error {
+	err := os.MkdirAll(cloneDestination, 0700)
+	if err != nil {
+		return err
+	}
+
+	currentGitRepo, err := LocateCurrentGitRepo()
+	if err != nil {
+		return err
+	}
+
+	return run(exec.Command("git", "clone", currentGitRepo, cloneDestination))
+}
+
+func gitCheckout(localRepo string, gitRef string) error {
+	return run(exec.Command("git", "-C", localRepo, "checkout", gitRef))
+}
+
+// BuildAt builds the go programSource using the version of the CNI library
+// at gitRef, and saves the resulting binary file at outputFilePath
+func BuildAt(programSource []byte, gitRef string, outputFilePath string) error {
+	tempGoPath, err := ioutil.TempDir("", "cni-git-")
+	if err != nil {
+		return err
+	}
+	defer os.RemoveAll(tempGoPath)
+
+	cloneDestination := filepath.Join(tempGoPath, "src", packageBaseName)
+	err = gitCloneThisRepo(cloneDestination)
+	if err != nil {
+		return err
+	}
+
+	err = gitCheckout(cloneDestination, gitRef)
+	if err != nil {
+		return err
+	}
+
+	rand.Seed(time.Now().UnixNano())
+	testPackageName := fmt.Sprintf("test-package-%x", rand.Int31())
+
+	err = createSingleFilePackage(tempGoPath, testPackageName, programSource)
+	if err != nil {
+		return err
+	}
+	defer removePackage(tempGoPath, testPackageName)
+
+	err = buildGoProgram(tempGoPath, testPackageName, outputFilePath)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}

pkg/version/testhelpers/testhelpers_suite_test.go

@@ -0,0 +1,27 @@
+// Copyright 2016 CNI authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package testhelpers_test
+
+import (
+	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/gomega"
+
+	"testing"
+)
+
+func TestTesthelpers(t *testing.T) {
+	RegisterFailHandler(Fail)
+	RunSpecs(t, "Testhelpers Suite")
+}

pkg/version/testhelpers/testhelpers_test.go

@@ -0,0 +1,106 @@
+// Copyright 2016 CNI authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+package testhelpers_test
+
+import (
+	"io/ioutil"
+	"os"
+	"os/exec"
+	"path/filepath"
+
+	"github.com/containernetworking/cni/pkg/version/testhelpers"
+	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/gomega"
+)
+
+var _ = Describe("BuildAt", func() {
+	var (
+		gitRef         string
+		outputFilePath string
+		outputDir      string
+		programSource  []byte
+	)
+	BeforeEach(func() {
+		programSource = []byte(`package main
+
+import "github.com/containernetworking/cni/pkg/skel"
+
+func c(_ *skel.CmdArgs) error { return nil }
+
+func main() { skel.PluginMain(c, c) }
+`)
+		gitRef = "f4364185253"
+
+		var err error
+		outputDir, err = ioutil.TempDir("", "bin")
+		Expect(err).NotTo(HaveOccurred())
+		outputFilePath = filepath.Join(outputDir, "some-binary")
+	})
+
+	AfterEach(func() {
+		Expect(os.RemoveAll(outputDir)).To(Succeed())
+	})
+
+	It("builds the provided source code using the CNI library at the given git ref", func() {
+		Expect(outputFilePath).NotTo(BeAnExistingFile())
+
+		err := testhelpers.BuildAt(programSource, gitRef, outputFilePath)
+		Expect(err).NotTo(HaveOccurred())
+
+		Expect(outputFilePath).To(BeAnExistingFile())
+
+		cmd := exec.Command(outputFilePath)
+		cmd.Env = []string{"CNI_COMMAND=VERSION"}
+		output, err := cmd.CombinedOutput()
+		Expect(err).To(BeAssignableToTypeOf(&exec.ExitError{}))
+		Expect(output).To(ContainSubstring("unknown CNI_COMMAND: VERSION"))
+	})
+})
+
+var _ = Describe("LocateCurrentGitRepo", func() {
+	It("returns the path to the root of the CNI git repo", func() {
+		path, err := testhelpers.LocateCurrentGitRepo()
+		Expect(err).NotTo(HaveOccurred())
+
+		AssertItIsTheCNIRepoRoot(path)
+	})
+
+	Context("when run from a different directory", func() {
+		BeforeEach(func() {
+			os.Chdir("..")
+		})
+
+		It("still finds the CNI repo root", func() {
+			path, err := testhelpers.LocateCurrentGitRepo()
+			Expect(err).NotTo(HaveOccurred())
+
+			AssertItIsTheCNIRepoRoot(path)
+		})
+	})
+})
+
+func AssertItIsTheCNIRepoRoot(path string) {
+	Expect(path).To(BeADirectory())
+	files, err := ioutil.ReadDir(path)
+	Expect(err).NotTo(HaveOccurred())
+
+	names := []string{}
+	for _, file := range files {
+		names = append(names, file.Name())
+	}
+
+	Expect(names).To(ContainElement("SPEC.md"))
+	Expect(names).To(ContainElement("libcni"))
+	Expect(names).To(ContainElement("cnitool"))
+}

test

@@ -11,7 +11,7 @@ set -e
 
 source ./build
 
-TESTABLE="libcni plugins/ipam/dhcp plugins/ipam/host-local plugins/main/loopback pkg/invoke pkg/ns pkg/skel pkg/types pkg/utils plugins/main/ipvlan plugins/main/macvlan plugins/main/bridge plugins/main/ptp plugins/test/noop pkg/utils/hwaddr pkg/ip pkg/version"
+TESTABLE="libcni plugins/ipam/dhcp plugins/ipam/host-local plugins/main/loopback pkg/invoke pkg/ns pkg/skel pkg/types pkg/utils plugins/main/ipvlan plugins/main/macvlan plugins/main/bridge plugins/main/ptp plugins/test/noop pkg/utils/hwaddr pkg/ip pkg/version pkg/version/testhelpers"
 FORMATTABLE="$TESTABLE pkg/testutils plugins/meta/flannel plugins/meta/tuning"
 
 # user has not provided PKG override