Publish ITWorx Pulse source

internal/metricsapi/handler.go

@@ -0,0 +1,33 @@
+package metricsapi
+
+import (
+	"encoding/json"
+	"net/http"
+
+	"github.com/itworx/pulse/internal/auth"
+	"github.com/itworx/pulse/internal/metriccatalog"
+	"github.com/itworx/pulse/internal/problem"
+)
+
+type Handler struct{ Registry metriccatalog.Registry }
+
+func (h Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	if r.Method != http.MethodGet || r.URL.Path != "/api/v1/metrics/catalog" {
+		http.NotFound(w, r)
+		return
+	}
+	if _, ok := auth.PrincipalFromContext(r.Context()); !ok {
+		problem.Write(w, r, http.StatusUnauthorized, "UNAUTHORIZED", "Authentication required", "Authentication is required to read the metric catalog.", nil)
+		return
+	}
+	w.Header().Set("Content-Type", "application/json")
+	w.Header().Set("Cache-Control", "private, max-age=60")
+	w.Header().Set("ETag", `"`+h.Registry.Version()+`"`)
+	if r.Header.Get("If-None-Match") == `"`+h.Registry.Version()+`"` {
+		w.WriteHeader(http.StatusNotModified)
+		return
+	}
+	if err := json.NewEncoder(w).Encode(h.Registry.Response()); err != nil {
+		return
+	}
+}