added hooks and spec file for dynatrace

modified test to fit logenv scenario

fixed download url to include nodejs agent

getting process agent path from manifest.json now

added error handling for agentpath() and fixed some returns

fixed wrong paths in returns

fixed return paths

fixed dynatrace-env.sh path

removed cf_spec since it's not used anymore in upstream

added detection for multiple services

added debug output to service detection

clarified log output

added integration tests for dynatrace agent

changed url

adapted urls to new format, added test for service detection

added hook test includes

removed pointless checks

added services cleanup

improved error message and var names, removed pointless '/'

added test for incomplete dynatrace service

added skiperrors flag and needed tests

made check for skiperrors a bit nicer

src/nodejs/hooks/dynatrace.go

@@ -0,0 +1,242 @@
+package hooks
+
+import (
+	"encoding/json"
+	"errors"
+	"io"
+	"io/ioutil"
+	"net/http"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"github.com/cloudfoundry/libbuildpack"
+)
+
+type Command interface {
+	Execute(string, io.Writer, io.Writer, string, ...string) error
+}
+
+type DynatraceHook struct {
+	libbuildpack.DefaultHook
+	Log     *libbuildpack.Logger
+	Command Command
+}
+
+func init() {
+	logger := libbuildpack.NewLogger(os.Stdout)
+	command := &libbuildpack.Command{}
+
+	libbuildpack.AddHook(DynatraceHook{
+		Log:     logger,
+		Command: command,
+	})
+}
+
+func (h DynatraceHook) AfterCompile(stager *libbuildpack.Stager) error {
+	h.Log.Debug("Checking for enabled dynatrace service...")
+
+	credentials := h.dtCredentials()
+	if credentials == nil {
+		h.Log.Debug("Dynatrace service credentials not found!")
+		return nil
+	}
+
+	h.Log.Info("Dynatrace service credentials found. Setting up Dynatrace PaaS agent.")
+
+	skipErrors := credentials["skiperrors"]
+
+	apiurl, present := credentials["apiurl"]
+	if !present {
+		apiurl = "https://" + credentials["environmentid"] + ".live.dynatrace.com/api"
+	}
+
+	url := apiurl + "/v1/deployment/installer/agent/unix/paas-sh/latest?include=nodejs&include=process&bitness=64&Api-Token=" + credentials["apitoken"]
+	installerPath := filepath.Join(os.TempDir(), "paasInstaller.sh")
+
+	h.Log.Debug("Downloading '%s' to '%s'", url, installerPath)
+	err := h.downloadFile(url, installerPath)
+	if err != nil {
+		if skipErrors == "true" {
+			h.Log.Warning("Error during installer download, skipping installation")
+			return nil
+		}
+		return err
+	}
+
+	h.Log.Debug("Making %s executable...", installerPath)
+	os.Chmod(installerPath, 0755)
+
+	h.Log.BeginStep("Starting Dynatrace PaaS agent installer")
+
+	if os.Getenv("BP_DEBUG") != "" {
+		err = h.Command.Execute("", os.Stdout, os.Stderr, installerPath, stager.BuildDir())
+	} else {
+		err = h.Command.Execute("", ioutil.Discard, ioutil.Discard, installerPath, stager.BuildDir())
+	}
+	if err != nil {
+		return err
+	}
+
+	h.Log.Info("Dynatrace PaaS agent installed.")
+
+	dynatraceEnvName := "dynatrace-env.sh"
+	installDir := "dynatrace/oneagent"
+	dynatraceEnvPath := filepath.Join(stager.DepDir(), "profile.d", dynatraceEnvName)
+	agentLibPath, err := h.agentPath(filepath.Join(stager.BuildDir(), installDir))
+	if err != nil {
+		h.Log.Error("Manifest handling failed!")
+		return err
+	}
+
+	agentLibPath = filepath.Join(installDir, agentLibPath)
+
+	_, err = os.Stat(filepath.Join(stager.BuildDir(), agentLibPath))
+	if os.IsNotExist(err) {
+		h.Log.Error("Agent library (%s) not found!", filepath.Join(installDir, agentLibPath))
+		return err
+	}
+
+	h.Log.BeginStep("Setting up Dynatrace PaaS agent injection...")
+	h.Log.Debug("Copy %s to %s", dynatraceEnvName, dynatraceEnvPath)
+	err = libbuildpack.CopyFile(filepath.Join(stager.BuildDir(), installDir, dynatraceEnvName), dynatraceEnvPath)
+	if err != nil {
+		return err
+	}
+
+	h.Log.Debug("Open %s for modification...", dynatraceEnvPath)
+	f, err := os.OpenFile(dynatraceEnvPath, os.O_APPEND|os.O_WRONLY, os.ModeAppend)
+	if err != nil {
+		return err
+	}
+
+	defer f.Close()
+
+	h.Log.Debug("Write LD_PRELOAD...")
+	_, err = f.WriteString("\nexport LD_PRELOAD=${HOME}/" + agentLibPath)
+	if err != nil {
+		return err
+	}
+
+	h.Log.Debug("Write DT_HOST_ID...")
+	_, err = f.WriteString("\nexport DT_HOST_ID=" + h.appName() + "_${CF_INSTANCE_INDEX}")
+	if err != nil {
+		return err
+	}
+
+	h.Log.Info("Dynatrace PaaS agent injection is set up.")
+
+	return nil
+}
+
+func (h DynatraceHook) dtCredentials() map[string]string {
+	type Service struct {
+		Name        string            `json:"name"`
+		Credentials map[string]string `json:"credentials"`
+	}
+	var vcapServices map[string][]Service
+
+	err := json.Unmarshal([]byte(os.Getenv("VCAP_SERVICES")), &vcapServices)
+	if err != nil {
+		return nil
+	}
+
+	var detectedServices []Service
+
+	for _, services := range vcapServices {
+		for _, service := range services {
+			if strings.Contains(service.Name, "dynatrace") &&
+					service.Credentials["environmentid"] != "" &&
+					service.Credentials["apitoken"] != "" {
+				detectedServices = append(detectedServices, service)
+			}
+		}
+	}
+
+	if len(detectedServices) == 1 {
+		h.Log.Debug("Found one matching service: %s", detectedServices[0].Name)
+		return detectedServices[0].Credentials
+	} else if len(detectedServices) > 1 {
+		h.Log.Warning("More than one matching service found!")
+	}
+
+	return nil
+}
+
+func (h DynatraceHook) appName() string {
+	var application struct {
+		Name string `json:"name"`
+	}
+	err := json.Unmarshal([]byte(os.Getenv("VCAP_APPLICATION")), &application)
+	if err != nil {
+		return ""
+	}
+
+	return application.Name
+}
+
+func (h DynatraceHook) downloadFile(url, path string) error {
+	out, err := os.Create(path)
+	if err != nil {
+		return err
+	}
+
+	defer out.Close()
+
+	resp, err := http.Get(url)
+	if err != nil {
+		return err
+	}
+
+	if resp.StatusCode != 200 {
+		return errors.New("Download returned with status " + resp.Status)
+	}
+
+	defer resp.Body.Close()
+
+	_, err = io.Copy(out, resp.Body)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (h DynatraceHook) agentPath(installDir string) (string, error) {
+	manifestPath := filepath.Join(installDir, "manifest.json")
+
+	type Binary struct {
+		Path string `json:"path"`
+		Md5 string `json:"md5"`
+		Version string `json:"version"`
+		Binarytype string `json:"binarytype,omitemtpy"`
+	}
+
+	type Architecture map[string][]Binary
+	type Technologies map[string]Architecture
+
+	type Manifest struct {
+		Tech Technologies`json:"technologies"`
+		Ver string `json:"version"`
+	}
+
+	var manifest Manifest
+
+	raw, err := ioutil.ReadFile(manifestPath)
+	if err != nil {
+		return "", err
+	}
+
+	err = json.Unmarshal(raw, &manifest) 
+	if err != nil {
+		return "", err
+	}
+
+	for _, binary := range manifest.Tech["process"]["linux-x86-64"] {
+		if binary.Binarytype ==	"primary" {
+			return binary.Path, nil
+		}
+	}
+
+	return "", errors.New("No primary binary for process agent found!")
+}