Merge pull request #14 from spinup-host/vicky/gh-3

gh-3: to support streaming logs using websocket
spinup-host · Jul 19, 2021 · ca09898 · ca09898
2 parents 78f7336 + ba56b92
commit ca09898
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Showing 3 changed files with 179 additions and 3 deletions.
diff --git a/api/streamlogs.go b/api/streamlogs.go
@@ -0,0 +1,174 @@
+package api
+
+import (
+	"io/ioutil"
+	"log"
+	"net/http"
+	"os"
+	"strconv"
+	"text/template"
+	"time"
+
+	"github.com/gorilla/websocket"
+)
+
+const (
+	// Time allowed to write the file to the client.
+	writeWait = 10 * time.Second
+
+	// Time allowed to read the next pong message from the client.
+	pongWait = 60 * time.Second
+
+	// Send pings to client with this period. Must be less than pongWait.
+	pingPeriod = (pongWait * 9) / 10
+
+	// Poll file for changes with this period.
+	filePeriod = 10 * time.Second
+)
+
+var (
+	homeTempl = template.Must(template.New("").Parse(homeHTML))
+	filename  = "/var/lib/docker/containers/1967dededef67f90df186c7569ccfa5d7d6828447bd47c4c48657c837990943a/1967dededef67f90df186c7569ccfa5d7d6828447bd47c4c48657c837990943a-json.log"
+	upgrader  = websocket.Upgrader{
+		ReadBufferSize:  1024,
+		WriteBufferSize: 1024,
+	}
+)
+
+func readFileIfModified(lastMod time.Time) ([]byte, time.Time, error) {
+	fi, err := os.Stat(filename)
+	if err != nil {
+		return nil, lastMod, err
+	}
+	if !fi.ModTime().After(lastMod) {
+		return nil, lastMod, nil
+	}
+	p, err := ioutil.ReadFile(filename)
+	if err != nil {
+		return nil, fi.ModTime(), err
+	}
+	return p, fi.ModTime(), nil
+}
+
+func reader(ws *websocket.Conn) {
+	defer ws.Close()
+	ws.SetReadLimit(512)
+	ws.SetReadDeadline(time.Now().Add(pongWait))
+	ws.SetPongHandler(func(string) error { ws.SetReadDeadline(time.Now().Add(pongWait)); return nil })
+	for {
+		_, _, err := ws.ReadMessage()
+		if err != nil {
+			break
+		}
+	}
+}
+
+func writer(ws *websocket.Conn, lastMod time.Time) {
+	lastError := ""
+	pingTicker := time.NewTicker(pingPeriod)
+	fileTicker := time.NewTicker(filePeriod)
+	defer func() {
+		pingTicker.Stop()
+		fileTicker.Stop()
+		ws.Close()
+	}()
+	for {
+		select {
+		case <-fileTicker.C:
+			var p []byte
+			var err error
+
+			p, lastMod, err = readFileIfModified(lastMod)
+
+			if err != nil {
+				if s := err.Error(); s != lastError {
+					lastError = s
+					p = []byte(lastError)
+				}
+			} else {
+				lastError = ""
+			}
+
+			if p != nil {
+				ws.SetWriteDeadline(time.Now().Add(writeWait))
+				if err := ws.WriteMessage(websocket.TextMessage, p); err != nil {
+					return
+				}
+			}
+		case <-pingTicker.C:
+			ws.SetWriteDeadline(time.Now().Add(writeWait))
+			if err := ws.WriteMessage(websocket.PingMessage, []byte{}); err != nil {
+				return
+			}
+		}
+	}
+}
+
+func StreamLogs(w http.ResponseWriter, r *http.Request) {
+	ws, err := upgrader.Upgrade(w, r, nil)
+	if err != nil {
+		if _, ok := err.(websocket.HandshakeError); !ok {
+			log.Println(err)
+		}
+		return
+	}
+
+	var lastMod time.Time
+	if n, err := strconv.ParseInt(r.FormValue("lastMod"), 16, 64); err == nil {
+		lastMod = time.Unix(0, n)
+	}
+
+	go writer(ws, lastMod)
+	reader(ws)
+}
+
+func Logs(w http.ResponseWriter, r *http.Request) {
+	if r.URL.Path != "/logs" {
+		http.Error(w, "Not found", http.StatusNotFound)
+		return
+	}
+	if r.Method != "GET" {
+		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
+		return
+	}
+	w.Header().Set("Content-Type", "text/html; charset=utf-8")
+	p, lastMod, err := readFileIfModified(time.Time{})
+	if err != nil {
+		p = []byte(err.Error())
+		lastMod = time.Unix(0, 0)
+	}
+	var v = struct {
+		Host    string
+		Data    string
+		LastMod string
+	}{
+		r.Host,
+		string(p),
+		strconv.FormatInt(lastMod.UnixNano(), 16),
+	}
+	homeTempl.Execute(w, &v)
+}
+
+const homeHTML = `<!DOCTYPE html>
+<html lang="en">
+    <head>
+        <title>WebSocket Example</title>
+    </head>
+    <body>
+        <pre id="fileData">{{.Data}}</pre>
+        <script type="text/javascript">
+            (function() {
+                var data = document.getElementById("fileData");
+                var conn = new WebSocket("wss://api.spinup.host/streamlogs?lastMod={{.LastMod}}");
+                conn.onclose = function(evt) {
+                    data.textContent = 'Connection closed';
+                }
+                conn.onmessage = function(evt) {
+                    console.log('file updated');
+                    data.textContent = evt.data;
+                }
+            })();
+        </script>
+    </body>
+</html>
+`
diff --git a/go.mod b/go.mod
@@ -6,9 +6,9 @@ require (
 	github.com/cloudflare/cloudflare-go v0.14.0
 	github.com/golang/gddo v0.0.0-20210115222349-20d68f94ee1f
 	github.com/google/go-cmp v0.5.1 // indirect
-	github.com/gorilla/websocket v1.4.2 // indirect
-	github.com/rs/cors v1.8.0 // indirect
+	github.com/gorilla/websocket v1.4.2
+	github.com/rs/cors v1.8.0
 	golang.org/x/time v0.0.0-20210220033141-f8bda1e9f3ba // indirect
 	golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1 // indirect
-	gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b // indirect
+	gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b
 )
diff --git a/main.go b/main.go
@@ -16,6 +16,8 @@ func main() {
 	mux.HandleFunc("/hello", api.Hello)
 	mux.HandleFunc("/createservice", api.CreateService)
 	mux.HandleFunc("/githubAuth", api.GithubAuth)
+	mux.HandleFunc("/logs", api.Logs)
+	mux.HandleFunc("/streamlogs", api.StreamLogs)
 	// TODO: remove http version
 	c := cors.New(cors.Options{
 		AllowedOrigins: []string{"https://spinup.host", "http://spinup.host"},