services/serve: refactor dev server handler (ignite#91)

* services/serve: refactor dev server handler

* updated frontend bindings.
* added new `pkg/xhttp` helper.
* added new `pkg/httpstatuschecker` helper.

* services/serve: simplify server status check

and add concurrent checks.

* services/serve: rework def of dev server's /status enpoint

starport/pkg/httpstatuschecker/httpstatuschecker.go

@@ -0,0 +1,56 @@
+// httpstatuschecker is a tool check health of http pages.
+package httpstatuschecker
+
+import (
+	"net/http"
+)
+
+type checker struct {
+	c      *http.Client
+	addr   string
+	method string
+}
+
+// Option used to customize checker.
+type Option func(*checker)
+
+// Client configures http client.
+func Client(c *http.Client) Option {
+	return func(cr *checker) {
+		cr.c = c
+	}
+}
+
+// Client configures http method.
+func Method(name string) Option {
+	return func(cr *checker) {
+		cr.method = name
+	}
+}
+
+// Check checks if given http addr is alive by applying options.
+func Check(addr string, options ...Option) (isAvailable bool, err error) {
+	cr := &checker{
+		c:      http.DefaultClient,
+		addr:   addr,
+		method: http.MethodGet,
+	}
+	for _, o := range options {
+		o(cr)
+	}
+	return cr.check()
+}
+
+func (c *checker) check() (bool, error) {
+	req, err := http.NewRequest(c.method, c.addr, nil)
+	if err != nil {
+		return false, err
+	}
+	res, err := c.c.Do(req)
+	if err != nil {
+		return false, nil
+	}
+	defer res.Body.Close()
+	isOKStatus := res.StatusCode >= http.StatusOK && res.StatusCode < http.StatusMultipleChoices
+	return isOKStatus, nil
+}

starport/pkg/httpstatuschecker/httpstatuschecker_test.go

@@ -0,0 +1,39 @@
+package httpstatuschecker
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestCheckStatus(t *testing.T) {
+	cases := []struct {
+		name           string
+		returnedStatus int
+		isAvaiable     bool
+	}{
+		{"200 OK", 200, true},
+		{"202 Accepted ", 202, true},
+		{"404 Not Found", 404, false},
+	}
+	for _, tt := range cases {
+		t.Run(tt.name, func(t *testing.T) {
+			ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+				w.WriteHeader(tt.returnedStatus)
+			}))
+			defer ts.Close()
+
+			isAvailable, err := Check(ts.URL)
+			require.NoError(t, err)
+			require.Equal(t, tt.isAvaiable, isAvailable)
+		})
+	}
+}
+
+func TestCheckServerUnreachable(t *testing.T) {
+	isAvailable, err := Check("http://localhost:63257")
+	require.NoError(t, err)
+	require.False(t, isAvailable)
+}

starport/pkg/xhttp/response.go

@@ -0,0 +1,41 @@
+package xhttp
+
+import (
+	"encoding/json"
+	"errors"
+	"net/http"
+)
+
+// ResponseJSON writes a JSON response to w by using status as http status and data
+// as payload.
+func ResponseJSON(w http.ResponseWriter, status int, data interface{}) error {
+	bdata, err := json.Marshal(data)
+	if err != nil {
+		status = http.StatusInternalServerError
+		bdata, _ = json.Marshal(NewErrorResponse(errors.New(http.StatusText(status))))
+	}
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(status)
+	w.Write(bdata)
+	return err
+}
+
+// ErrorResponseBody is the skeleton for error messages that should be sent to
+// client.
+type ErrorResponseBody struct {
+	Error ErrorResponse `json:"error"`
+}
+
+// ErrorResponse holds the error message.
+type ErrorResponse struct {
+	Message string `json:"message"`
+}
+
+// NewErrorResponse creates a new http error response from err.
+func NewErrorResponse(err error) ErrorResponseBody {
+	return ErrorResponseBody{
+		Error: ErrorResponse{
+			Message: err.Error(),
+		},
+	}
+}

starport/pkg/xhttp/response_test.go

@@ -0,0 +1,34 @@
+package xhttp
+
+import (
+	"encoding/json"
+	"errors"
+	"io/ioutil"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestResponseJSON(t *testing.T) {
+	w := httptest.NewRecorder()
+	data := map[string]interface{}{"a": 1}
+	require.NoError(t, ResponseJSON(w, http.StatusCreated, data))
+	resp := w.Result()
+
+	require.Equal(t, http.StatusCreated, resp.StatusCode)
+	require.Equal(t, "application/json", resp.Header.Get("Content-Type"))
+
+	body, _ := ioutil.ReadAll(resp.Body)
+	dataJSON, _ := json.Marshal(data)
+	require.Equal(t, dataJSON, body)
+}
+
+func TestNewErrorResponse(t *testing.T) {
+	require.Equal(t, ErrorResponseBody{
+		Error: ErrorResponse{
+			Message: "error!",
+		},
+	}, NewErrorResponse(errors.New("error!")))
+}

starport/services/serve/dev.go

@@ -1,57 +1,106 @@
 package starportserve
 
 import (
-	"encoding/json"
 	"net/http"
 
 	"github.com/gobuffalo/packr/v2"
 	"github.com/gorilla/mux"
+	"github.com/tendermint/starport/starport/pkg/httpstatuschecker"
+	"github.com/tendermint/starport/starport/pkg/xhttp"
+	"golang.org/x/sync/errgroup"
 )
 
-// newDevHandler creates a new development server handler.
-func newDevHandler(app App) http.Handler {
+const (
+	appNodeInfoEndpoint = "/node_info"
+)
+
+// serviceStatusResponse holds the status of development environment and http services
+// needed for development.
+type statusResponse struct {
+	Status serviceStatus `json:"status"`
+	Env    env           `json:"env"`
+}
+
+// serviceStatus holds the availibity status of http services.
+type serviceStatus struct {
+	IsConsensusEngineAlive bool `json:"is_consensus_engine_alive"`
+	IsMyAppBackendAlive    bool `json:"is_my_app_backend_alive"`
+	IsMyAppFrontendAlive   bool `json:"is_my_app_frontend_alive"`
+}
+
+// env holds info about development environment.
+type env struct {
+	ChainID string `json:"chain_id"`
+	NodeJS  bool   `json:"node_js"`
+}
+
+// development handler builder.
+type development struct {
+	app  App
+	conf Config
+}
+
+// Config used to configure development handler.
+type Config struct {
+	EngineAddr            string
+	AppBackendAddr        string
+	AppFrontendAddr       string
+	DevFrontendAssetsPath string
+}
+
+// newDevHandler creates a new development server handler for app by given conf.
+func newDevHandler(app App, conf Config) http.Handler {
+	dev := &development{app, conf}
 	router := mux.NewRouter()
-	devUI := packr.New("ui/dist", "../../ui/dist")
-	router.HandleFunc("/env", func(w http.ResponseWriter, r *http.Request) {
-		env := Env{app.Name, isCommandAvailable("node")}
-		js, err := json.Marshal(env)
-		if err != nil {
-			http.Error(w, err.Error(), http.StatusInternalServerError)
+	router.Handle("/status", dev.statusHandler()).Methods(http.MethodGet)
+	router.PathPrefix("/").Handler(dev.devAssetsHandler()).Methods(http.MethodGet)
+	return router
+}
+
+func (d *development) devAssetsHandler() http.Handler {
+	return http.FileServer(packr.New("ui/dist", d.conf.DevFrontendAssetsPath))
+}
+
+func (d *development) statusHandler() http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		var (
+			engineStatus,
+			appBackendStatus,
+			appFrontendStatus bool
+		)
+		g := &errgroup.Group{}
+		g.Go(func() (err error) {
+			engineStatus, err = httpstatuschecker.Check(d.conf.EngineAddr)
+			return
+		})
+		g.Go(func() (err error) {
+			appBackendStatus, err = httpstatuschecker.Check(d.conf.AppBackendAddr + appNodeInfoEndpoint)
+			return
+		})
+		g.Go(func() (err error) {
+			appFrontendStatus, err = httpstatuschecker.Check(d.conf.AppFrontendAddr)
+			return
+		})
+		if err := g.Wait(); err != nil {
+			xhttp.ResponseJSON(w, http.StatusInternalServerError, xhttp.NewErrorResponse(err))
 			return
 		}
-		w.Header().Set("Content-Type", "application/json")
-		w.Write(js)
-	})
-	router.HandleFunc("/api", func(w http.ResponseWriter, r *http.Request) {
-		res, err := http.Get("http://localhost:1317/node_info")
-		if err != nil || res.StatusCode != 200 {
-			w.WriteHeader(http.StatusInternalServerError)
-			w.Write([]byte("500 error"))
-		} else if res.StatusCode == 200 {
-			w.WriteHeader(http.StatusOK)
-			w.Write([]byte("200 ok"))
-		}
-	})
-	router.HandleFunc("/rpc", func(w http.ResponseWriter, r *http.Request) {
-		res, err := http.Get("http://localhost:26657")
-		if err != nil {
-			w.WriteHeader(http.StatusInternalServerError)
-		} else if res.StatusCode == 200 {
-			w.WriteHeader(http.StatusOK)
-		} else {
-			w.WriteHeader(http.StatusInternalServerError)
-		}
-	})
-	router.HandleFunc("/frontend", func(w http.ResponseWriter, r *http.Request) {
-		res, err := http.Get("http://localhost:8080")
-		if err != nil {
-			w.WriteHeader(http.StatusInternalServerError)
-		} else if res.StatusCode == 200 {
-			w.WriteHeader(http.StatusOK)
-		} else {
-			w.WriteHeader(http.StatusInternalServerError)
+
+		resp := statusResponse{
+			Env: d.env(),
+			Status: serviceStatus{
+				IsConsensusEngineAlive: engineStatus,
+				IsMyAppBackendAlive:    appBackendStatus,
+				IsMyAppFrontendAlive:   appFrontendStatus,
+			},
 		}
+		xhttp.ResponseJSON(w, http.StatusOK, resp)
 	})
-	router.PathPrefix("/").Handler(http.FileServer(devUI))
-	return router
+}
+
+func (d *development) env() env {
+	return env{
+		d.app.Name,
+		isCommandAvailable("node"),
+	}
 }

starport/services/serve/serve.go

@@ -59,12 +59,6 @@ func Serve(ctx context.Context, app App, verbose bool) error {
 	return w.Start(time.Millisecond * 1000)
 }
 
-// Env ...
-type Env struct {
-	ChainID string `json:"chain_id"`
-	NodeJS  bool   `json:"node_js"`
-}
-
 func startServe(ctx context.Context, app App, verbose bool) error {
 	var (
 		steps step.Steps
@@ -191,7 +185,13 @@ func runDevServer(app App, verbose bool) error {
 	} else {
 		fmt.Printf("\n🚀 Get started: http://localhost:12345/\n\n")
 	}
-	return http.ListenAndServe(":12345", newDevHandler(app))
+	conf := Config{
+		EngineAddr:            "http://localhost:26657",
+		AppBackendAddr:        "http://localhost:1317",
+		AppFrontendAddr:       "http://localhost:8080",
+		DevFrontendAssetsPath: "../../ui/dist",
+	} // TODO get vals from const
+	return http.ListenAndServe(":12345", newDevHandler(app, conf))
 }
 
 func isCommandAvailable(name string) bool {