Fix query params and small refactor (heroku#22)

* Fix query params and small refactor

Adds a helper function to remove some of the error checking boilerplate,
and loops through files we need to build instead of doing copy pasta.

* Use log.Panic over log.Error in server

go.sum

@@ -12,6 +12,7 @@ github.com/aybabtme/rgbterm v0.0.0-20170906152045-cc83f3b3ce59/go.mod h1:q/89r3U
 github.com/buildpack/libbuildpack v1.11.0 h1:yIjsdJuQaTspDE/6wjkUX4OF56YRtMHajbARQLmm8KU=
 github.com/buildpack/libbuildpack v1.11.0/go.mod h1:tKGgGnBYfOL23Ma4JWM8ucBcGX6Im3p1WTmKPixDPPM=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/fatih/color v1.7.0/go.mod h1:Zm6kSWBoL9eyXnKyktHP6abPY2pDugNf5KwzbycvMj4=
 github.com/felixge/httpsnoop v1.0.1 h1:lvB5Jl89CsZtGIWuTcDM1E/vkVs49/Ml7JJe07l8SPQ=
@@ -62,6 +63,7 @@ github.com/onsi/gomega v1.5.0/go.mod h1:ex+gbHU/CVuBBDIJjb2X0qEXbFg53c61hWP/1Cpa
 github.com/pkg/errors v0.8.1 h1:iURUrRGxPUNPdy5/HRSm+Yj6okJ6UtLINN0Q9M4+h3I=
 github.com/pkg/errors v0.8.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 github.com/pkg/errors v0.8.2-0.20190227000051-27936f6d90f9/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/rogpeppe/fastuuid v1.1.0/go.mod h1:jVj6XXZzXRy/MSR5jhDC/2q6DgLz+nrA6LYCDYWNEvQ=
 github.com/rollbar/rollbar-go v1.0.2/go.mod h1:AcFs5f0I+c71bpHlXNNDbOWJiKwjFDtISeXco0L5PKQ=
@@ -78,6 +80,7 @@ github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+
 github.com/stretchr/objx v0.1.1/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
 github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXfy6kDkUVs=
 github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
+github.com/stretchr/testify v1.6.1 h1:hDPOHmpOpP40lSULcqw7IrRb/u7w6RpDC9399XyoNd0=
 github.com/stretchr/testify v1.6.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 github.com/tj/assert v0.0.0-20171129193455-018094318fb0/go.mod h1:mZ9/Rh9oLWpLLDRpvE+3b7gP/C2YyLFYxNmcLnPTMe0=
 github.com/tj/assert v0.0.3/go.mod h1:Ne6X72Q+TB1AteidzQncjw9PabbMp4PBMZ1k+vd1Pvk=
@@ -115,4 +118,5 @@ gopkg.in/yaml.v2 v2.2.1/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
 gopkg.in/yaml.v2 v2.2.2 h1:ZCJp+EgiOT7lHqUV2J862kp8Qj64Jo6az82+3Td9dZw=
 gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
+gopkg.in/yaml.v3 v3.0.0-20200605160147-a5ece683394c h1:grhR+C34yXImVGp7EzNk+DTIk+323eIUWOmEevy6bDo=
 gopkg.in/yaml.v3 v3.0.0-20200605160147-a5ece683394c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

server/main.go

@@ -27,34 +27,31 @@ func main() {
 	r.HandleFunc("/health", HealthHandler)
 
 	port := fmt.Sprintf(":%s", conf.Port)
-	err := rollbar.WrapAndWait(http.ListenAndServe(port, handlers.CompressHandler(r)))
+	rollbar.WrapAndWait(http.ListenAndServe(port, handlers.CompressHandler(r)))
 
-	if err == nil {
-		log.Error(err)
-	}
 	log.Info("server started")
 }
 
 func NameHandler(w http.ResponseWriter, r *http.Request) {
 	vars := mux.Vars(r)
 	id := fmt.Sprintf("%s/%s", vars["namespace"], vars["name"])
 	var version, name, api, stacks string
-	var found bool
+	params := r.URL.Query()
 
-	if version, found = mux.Vars(r)["version"]; !found {
+	if version = params.Get("version"); version == "" {
 		version = "0.1"
 	}
 
-	if name, found = mux.Vars(r)["name"]; !found {
+	if name = params.Get("name"); name == "" {
 		name = "0.1"
 	}
 
-	if api, found = mux.Vars(r)["api"]; !found {
+	if api = params.Get("api"); api == "" {
 		api = "0.4"
 	}
 
-	if stacks, found = mux.Vars(r)["stacks"]; !found {
-		if stack, found := mux.Vars(r)["stack"]; !found {
+	if stacks = params.Get("stacks"); stacks == "" {
+		if stack := params.Get("stack"); stack == "" {
 			stacks = "heroku-18,heroku-20"
 		} else {
 			stacks = stack
@@ -67,27 +64,25 @@ func NameHandler(w http.ResponseWriter, r *http.Request) {
 	dir, _ := os.Getwd()
 	dir, _ = ioutil.TempDir(dir, uuid.New().String())
 	defer os.RemoveAll(dir)
-	_ = os.Chdir(dir)
+	handlePanic(os.Chdir(dir))
 
 	log.Infof("at=shim file=%s", shimmedBuildpack)
 
-	_ = os.Mkdir("bin", 0777)
-	input, _ := ioutil.ReadFile(fmt.Sprintf("%s/bin/build", shimDir))
-	_ = ioutil.WriteFile("bin/build", input, 0700)
-
-	input, _ = ioutil.ReadFile(fmt.Sprintf("%s/bin/detect", shimDir))
-	_ = ioutil.WriteFile("bin/detect", input, 0700)
-
-	input, _ = ioutil.ReadFile(fmt.Sprintf("%s/bin/release", shimDir))
-	_ = ioutil.WriteFile("bin/release", input, 0700)
+	handlePanic(os.Mkdir("bin", 0777))
 
-	input, _ = ioutil.ReadFile(fmt.Sprintf("%s/bin/exports", shimDir))
-	_ = ioutil.WriteFile("bin/exports", input, 0700)
+	files := []string{"build", "detect", "release", "exports"}
+	for _, f := range files {
+		input, err := ioutil.ReadFile(fmt.Sprintf("%s/bin/%s", shimDir, f))
+		handlePanic(err)
+		err = ioutil.WriteFile(fmt.Sprintf("bin/%s", f), input, 0700)
+		handlePanic(err)
+	}
 
 	log.Infof("at=descriptor file=%s api=%s id=%s version=%s name=%s stacks=%s",
 		shimmedBuildpack, api, id, version, name, stacks)
 
-	file, _ := os.Create("buildpack.toml")
+	file, err := os.Create("buildpack.toml")
+	handlePanic(err)
 
 	bp := fmt.Sprintf("api = \"%s\"\n\n[buildpack]\nid = \"%s\"\nversion = \"%s\"\nname = \"%s\"\n", api, id, version, name)
 
@@ -96,31 +91,28 @@ func NameHandler(w http.ResponseWriter, r *http.Request) {
 		bp = bp + s
 	}
 
-	_, _ = file.WriteString(bp)
+	_, err = file.WriteString(bp)
+	handlePanic(err)
 	target_dir := "target"
-	_ = os.Mkdir(target_dir, 0777)
+	handlePanic(os.Mkdir(target_dir, 0777))
 
 	url := fmt.Sprintf("https://buildpack-registry.s3.amazonaws.com/buildpacks/%s.tgz", id)
 	log.Infof("at=download file=%s url=%s", shimmedBuildpack, url)
 	cmd := fmt.Sprintf(`curl --retry 3 --silent --location "%s" | tar xzm -C %s`, url, target_dir)
 
-	_, err := exec.Command("bash", "-c", cmd).Output()
-	if err != nil {
-		log.Error(err)
-	}
+	_, err = exec.Command("bash", "-c", cmd).Output()
+	handlePanic(err)
+	handlePanic(os.Chdir(shimDir))
 
-	_ = os.Chdir(shimDir)
 	cmd = fmt.Sprintf("tar cz --file=%s --directory=%s .", shimmedBuildpack, dir)
 
 	_, err = exec.Command("bash", "-c", cmd).Output()
+	handlePanic(err)
 	defer fmt.Printf("at=cleanup file=%s", shimmedBuildpack)
 	defer os.Remove(shimmedBuildpack)
 
-	if err != nil {
-		log.Error(err)
-	}
-
-	fstat, _ := file.Stat()
+	fstat, err := file.Stat()
+	handlePanic(err)
 	log.Infof("at=send file=%s size=%d", shimmedBuildpack, fstat.Size())
 	w.Header().Add("Content-Type", "application/x-gzip")
 	http.ServeFile(w, r, shimmedBuildpack)
@@ -131,3 +123,9 @@ func HealthHandler(w http.ResponseWriter, r *http.Request) {
 	fmt.Fprint(w, "health check ok")
 	log.Info("health check ok")
 }
+
+func handlePanic(e error) {
+	if e != nil {
+		log.Panic(e)
+	}
+}