[v8.4.x] Plugins: Make backend plugin metrics endpoints available with optional authentication (#47004)

pkg/api/plugin_metrics.go

@@ -0,0 +1,44 @@
+package api
+
+import (
+	"errors"
+	"net/http"
+	"strings"
+
+	"github.com/grafana/grafana/pkg/plugins/backendplugin"
+	"github.com/grafana/grafana/pkg/web"
+)
+
+func (hs *HTTPServer) pluginMetricsEndpoint(ctx *web.Context) {
+	if !hs.Cfg.MetricsEndpointEnabled {
+		return
+	}
+
+	if ctx.Req.Method != http.MethodGet || !strings.HasPrefix(ctx.Req.URL.Path, "/metrics/plugins/") {
+		return
+	}
+
+	if hs.metricsEndpointBasicAuthEnabled() && !BasicAuthenticatedRequest(ctx.Req, hs.Cfg.MetricsEndpointBasicAuthUsername, hs.Cfg.MetricsEndpointBasicAuthPassword) {
+		ctx.Resp.WriteHeader(http.StatusUnauthorized)
+		return
+	}
+
+	pathParts := strings.SplitAfter(ctx.Req.URL.Path, "/")
+	pluginID := pathParts[len(pathParts)-1]
+
+	resp, err := hs.pluginClient.CollectMetrics(ctx.Req.Context(), pluginID)
+	if err != nil {
+		if errors.Is(err, backendplugin.ErrPluginNotRegistered) {
+			ctx.Resp.WriteHeader(http.StatusNotFound)
+			return
+		}
+
+		ctx.Resp.WriteHeader(http.StatusInternalServerError)
+		return
+	}
+
+	ctx.Resp.Header().Set("Content-Type", "text/plain")
+	if _, err := ctx.Resp.Write(resp.PrometheusMetrics); err != nil {
+		hs.log.Error("Failed to write to response", "err", err)
+	}
+}