Work on #62: Add uptime percentage + badges

controller/badge.go

@@ -0,0 +1,108 @@
+package controller
+
+import (
+	"fmt"
+	"net/http"
+	"strings"
+	"time"
+
+	"github.com/TwinProduction/gatus/core"
+	"github.com/TwinProduction/gatus/watchdog"
+	"github.com/gorilla/mux"
+)
+
+// badgeHandler handles the automatic generation of badge based on the group name and service name passed.
+//
+// Valid values for {duration}: 7d, 24h, 1h
+// Pattern for {identifier}: group-<GROUP_NAME>-service-<SERVICE_NAME>.svg
+func badgeHandler(writer http.ResponseWriter, request *http.Request) {
+	variables := mux.Vars(request)
+	duration := variables["duration"]
+	// group-<GROUP_NAME>-service-<SERVICE_NAME>.svg
+	identifier := variables["identifier"]
+	if duration != "7d" && duration != "24h" && duration != "1h" {
+		writer.WriteHeader(http.StatusBadRequest)
+		_, _ = writer.Write([]byte("Durations supported: 7d, 24h, 1h"))
+		return
+	}
+	parts := strings.Split(identifier, "-service-")
+	if len(parts) != 2 || !strings.HasPrefix(identifier, "group-") || !strings.HasSuffix(identifier, ".svg") {
+		writer.WriteHeader(http.StatusBadRequest)
+		_, _ = writer.Write([]byte("Invalid path: Pattern should look like /group-<GROUP_NAME>-service-<SERVICE_NAME>.svg"))
+		return
+	}
+	groupName := strings.TrimPrefix(parts[0], "group-")
+	serviceName := strings.TrimSuffix(parts[1], ".svg")
+	uptime := watchdog.GetUptimeByServiceGroupAndName(groupName, serviceName)
+	if uptime == nil {
+		writer.WriteHeader(http.StatusNotFound)
+		_, _ = writer.Write([]byte("Requested service not found"))
+		return
+	}
+	formattedDate := time.Now().Format(http.TimeFormat)
+	writer.Header().Set("Cache-Control", "no-cache, no-store, must-revalidate")
+	writer.Header().Set("Date", formattedDate)
+	writer.Header().Set("Expires", formattedDate)
+	writer.Header().Set("Content-Type", "image/svg+xml")
+	_, _ = writer.Write(generateSVG(duration, uptime))
+}
+
+func generateSVG(duration string, uptime *core.Uptime) []byte {
+	var labelWidth, valueWidth, valueWidthAdjustment int
+	var color string
+	var value float64
+	switch duration {
+	case "7d":
+		labelWidth = 65
+		value = uptime.LastSevenDays
+	case "24h":
+		labelWidth = 70
+		value = uptime.LastTwentyFourHours
+	case "1h":
+		labelWidth = 65
+		value = uptime.LastHour
+	default:
+	}
+	if value >= 0.8 {
+		color = "#40cc11"
+	} else {
+		color = "#c7130a"
+	}
+	sanitizedValue := strings.TrimRight(strings.TrimRight(fmt.Sprintf("%.2f", value*100), "0"), ".") + "%"
+	if strings.Contains(sanitizedValue, ".") {
+		valueWidthAdjustment = -10
+	}
+	valueWidth = (len(sanitizedValue) * 11) + valueWidthAdjustment
+	width := labelWidth + valueWidth
+	labelX := labelWidth / 2
+	valueX := labelWidth + (valueWidth / 2)
+	svg := []byte(fmt.Sprintf(`<svg xmlns="http://www.w3.org/2000/svg" width="%d" height="20">
+  <linearGradient id="b" x2="0" y2="100%%">
+    <stop offset="0" stop-color="#bbb" stop-opacity=".1"/>
+    <stop offset="1" stop-opacity=".1"/>
+  </linearGradient>
+  <mask id="a">
+    <rect width="%d" height="20" rx="3" fill="#fff"/>
+  </mask>
+  <g mask="url(#a)">
+    <path fill="#555" d="M0 0h%dv20H0z"/>
+    <path fill="%s" d="M%d 0h%dv20H%dz"/>
+    <path fill="url(#b)" d="M0 0h%dv20H0z"/>
+  </g>
+  <g fill="#fff" text-anchor="middle" font-family="DejaVu Sans,Verdana,Geneva,sans-serif" font-size="11">
+    <text x="%d" y="15" fill="#010101" fill-opacity=".3">
+      uptime %s
+    </text>
+    <text x="%d" y="14">
+      uptime %s
+    </text>
+    <text x="%d" y="15" fill="#010101" fill-opacity=".3">
+      %s
+    </text>
+    <text x="%d" y="14">
+      %s
+    </text>
+  </g>
+</svg>`, width, width, labelWidth, color, labelWidth, valueWidth, labelWidth, width, labelX, duration, labelX, duration, valueX, sanitizedValue, valueX, sanitizedValue))
+	return svg
+}

controller/controller.go

@@ -0,0 +1,100 @@
+package controller
+
+import (
+	"bytes"
+	"compress/gzip"
+	"fmt"
+	"log"
+	"net/http"
+	"strings"
+	"time"
+
+	"github.com/TwinProduction/gatus/config"
+	"github.com/TwinProduction/gatus/security"
+	"github.com/TwinProduction/gatus/watchdog"
+	"github.com/gorilla/mux"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
+)
+
+const (
+	cacheTTL = 10 * time.Second
+)
+
+var (
+	cachedServiceStatuses          []byte
+	cachedServiceStatusesGzipped   []byte
+	cachedServiceStatusesTimestamp time.Time
+)
+
+// Handle creates the router and starts the server
+func Handle() {
+	cfg := config.Get()
+	router := CreateRouter(cfg)
+	server := &http.Server{
+		Addr:         fmt.Sprintf("%s:%d", cfg.Web.Address, cfg.Web.Port),
+		Handler:      router,
+		ReadTimeout:  15 * time.Second,
+		WriteTimeout: 15 * time.Second,
+		IdleTimeout:  15 * time.Second,
+	}
+	log.Printf("[controller][Handle] Listening on %s%s\n", cfg.Web.SocketAddress(), cfg.Web.ContextRoot)
+	log.Fatal(server.ListenAndServe())
+}
+
+// CreateRouter creates the router for the http server
+func CreateRouter(cfg *config.Config) *mux.Router {
+	router := mux.NewRouter()
+	statusesHandler := serviceStatusesHandler
+	if cfg.Security != nil && cfg.Security.IsValid() {
+		statusesHandler = security.Handler(serviceStatusesHandler, cfg.Security)
+	}
+	router.HandleFunc("/favicon.ico", favIconHandler).Methods("GET") // favicon needs to be always served from the root
+	router.HandleFunc(cfg.Web.PrependWithContextRoot("/api/v1/statuses"), statusesHandler).Methods("GET")
+	router.HandleFunc(cfg.Web.PrependWithContextRoot("/api/v1/badges/uptime/{duration}/{identifier}"), badgeHandler).Methods("GET")
+	router.HandleFunc(cfg.Web.PrependWithContextRoot("/health"), healthHandler).Methods("GET")
+	router.PathPrefix(cfg.Web.ContextRoot).Handler(GzipHandler(http.StripPrefix(cfg.Web.ContextRoot, http.FileServer(http.Dir("./static")))))
+	if cfg.Metrics {
+		router.Handle(cfg.Web.PrependWithContextRoot("/metrics"), promhttp.Handler()).Methods("GET")
+	}
+	return router
+}
+
+func serviceStatusesHandler(writer http.ResponseWriter, r *http.Request) {
+	if isExpired := cachedServiceStatusesTimestamp.IsZero() || time.Now().Sub(cachedServiceStatusesTimestamp) > cacheTTL; isExpired {
+		buffer := &bytes.Buffer{}
+		gzipWriter := gzip.NewWriter(buffer)
+		data, err := watchdog.GetJSONEncodedServiceStatuses()
+		if err != nil {
+			log.Printf("[main][serviceStatusesHandler] Unable to marshal object to JSON: %s", err.Error())
+			writer.WriteHeader(http.StatusInternalServerError)
+			_, _ = writer.Write([]byte("Unable to marshal object to JSON"))
+			return
+		}
+		gzipWriter.Write(data)
+		gzipWriter.Close()
+		cachedServiceStatuses = data
+		cachedServiceStatusesGzipped = buffer.Bytes()
+		cachedServiceStatusesTimestamp = time.Now()
+	}
+	var data []byte
+	if strings.Contains(r.Header.Get("Accept-Encoding"), "gzip") {
+		writer.Header().Set("Content-Encoding", "gzip")
+		data = cachedServiceStatusesGzipped
+	} else {
+		data = cachedServiceStatuses
+	}
+	writer.Header().Add("Content-type", "application/json")
+	writer.WriteHeader(http.StatusOK)
+	_, _ = writer.Write(data)
+}
+
+func healthHandler(writer http.ResponseWriter, _ *http.Request) {
+	writer.Header().Add("Content-type", "application/json")
+	writer.WriteHeader(http.StatusOK)
+	_, _ = writer.Write([]byte("{\"status\":\"UP\"}"))
+}
+
+// favIconHandler handles requests for /favicon.ico
+func favIconHandler(writer http.ResponseWriter, request *http.Request) {
+	http.ServeFile(writer, request, "./static/favicon.ico")
+}

controller/gzip.go

@@ -0,0 +1,51 @@
+package controller
+
+import (
+	"compress/gzip"
+	"io"
+	"io/ioutil"
+	"net/http"
+	"strings"
+	"sync"
+)
+
+var gzPool = sync.Pool{
+	New: func() interface{} {
+		return gzip.NewWriter(ioutil.Discard)
+	},
+}
+
+type gzipResponseWriter struct {
+	io.Writer
+	http.ResponseWriter
+}
+
+// WriteHeader sends an HTTP response header with the provided status code.
+// It also deletes the Content-Length header, since the GZIP compression may modify the size of the payload
+func (w *gzipResponseWriter) WriteHeader(status int) {
+	w.Header().Del("Content-Length")
+	w.ResponseWriter.WriteHeader(status)
+}
+
+// Write writes len(b) bytes from b to the underlying data stream.
+func (w *gzipResponseWriter) Write(b []byte) (int, error) {
+	return w.Writer.Write(b)
+}
+
+// GzipHandler compresses the response of a given handler if the request's headers specify that the client
+// supports gzip encoding
+func GzipHandler(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(writer http.ResponseWriter, r *http.Request) {
+		// If the request doesn't specify that it supports gzip, then don't compress it
+		if !strings.Contains(r.Header.Get("Accept-Encoding"), "gzip") {
+			next.ServeHTTP(writer, r)
+			return
+		}
+		writer.Header().Set("Content-Encoding", "gzip")
+		gz := gzPool.Get().(*gzip.Writer)
+		defer gzPool.Put(gz)
+		gz.Reset(writer)
+		defer gz.Close()
+		next.ServeHTTP(&gzipResponseWriter{ResponseWriter: writer, Writer: gz}, r)
+	})
+}