Add new cf.Push helper

- generates an app manifest instead of using command-line args to the
"cf push" command

[#167771970](https://www.pivotaltracker.com/story/show/167771970)

Co-authored-by: Dave Walter <[email protected]>

Author: acosta11

cf/push.go

@@ -0,0 +1,89 @@
+package cf
+
+import (
+	"fmt"
+	"io/ioutil"
+	"path/filepath"
+	"strconv"
+	"time"
+
+	"github.com/onsi/ginkgo"
+	"github.com/onsi/gomega/gexec"
+	"gopkg.in/yaml.v2"
+)
+
+type Manifest struct {
+	Applications []Application
+}
+
+type Application struct {
+	Buildpacks []string `yaml:omitempty`
+	Command    string   `yaml:omitempty`
+	Instances  int      `yaml:omitempty`
+	Memory     string   `yaml:omitempty`
+	Name       string
+	Path       string              `yaml:omitempty`
+	Routes     []map[string]string `yaml:omitempty`
+}
+
+var Push = func(appName string, args ...string) *gexec.Session {
+	tmpDir, err := ioutil.TempDir("", "")
+	if err != nil {
+		panic(err)
+	}
+
+	app := Application{
+		Name: appName,
+	}
+
+	for i := 0; i < len(args); i += 2 {
+		switch args[i] {
+		case "-b":
+			app.Buildpacks = append(app.Buildpacks, args[i+1])
+		case "-c":
+			app.Command = args[i+1]
+		case "-d":
+			app.Routes = append(app.Routes, map[string]string{"route": fmt.Sprintf("%s.%s", appName, args[i+1])})
+		case "-i":
+			instances, err := strconv.Atoi(args[i+1])
+			if err != nil {
+				panic(err)
+			}
+			app.Instances = instances
+		case "-m":
+			app.Memory = args[i+1]
+		case "-p":
+			path, err := filepath.Abs(args[i+1])
+			if err != nil {
+				panic(err)
+			}
+			app.Path = path
+		}
+	}
+
+	manifest := Manifest{}
+
+	manifest.Applications = append(manifest.Applications, app)
+
+	manifestText, err := yaml.Marshal(manifest)
+	if err != nil {
+		panic(err)
+	}
+
+	manifestPath := filepath.Join(tmpDir, "manifest.yml")
+	err = ioutil.WriteFile(manifestPath, manifestText, 0644)
+	if err != nil {
+		panic(err)
+	}
+
+	fmt.Fprintf(
+		ginkgo.GinkgoWriter,
+		"\n[%s]> Generated app manifest:\n%s\n",
+		time.Now().UTC().Format("2006-01-02 15:04:05.00 (MST)"),
+		string(manifestText),
+	)
+
+	return Cf("push",
+		"-f", manifestPath,
+	)
+}