Publish ITWorx Pulse source

internal/metricquery/handler.go

@@ -0,0 +1,125 @@
+package metricquery
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"errors"
+	"io"
+	"net/http"
+	"strings"
+
+	"github.com/itworx/pulse/internal/auth"
+	"github.com/itworx/pulse/internal/problem"
+	"github.com/itworx/pulse/internal/promqlbinding"
+	"github.com/itworx/pulse/internal/queryplan"
+)
+
+const maxRequestBody = 64 << 10
+
+type Handler struct{ Service *Service }
+
+func (h Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	if r.Method != http.MethodPost {
+		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 query metrics.", nil)
+		return
+	}
+	if h.Service == nil {
+		problem.Write(w, r, http.StatusServiceUnavailable, "METRIC_SOURCE_UNAVAILABLE", "Metric source unavailable", "The configured metric source is not available.", nil)
+		return
+	}
+	var response Response
+	var err error
+	switch strings.TrimPrefix(r.URL.Path, "/api/v1/metrics/") {
+	case "inspect":
+		var request queryplan.Request
+		if !decodeJSON(w, r, &request) {
+			return
+		}
+		inspector, inspectErr := h.Service.Inspect(r.Context(), request)
+		if inspectErr != nil {
+			writeQueryError(w, r, inspectErr)
+			return
+		}
+		w.Header().Set("Content-Type", "application/json")
+		_ = json.NewEncoder(w).Encode(map[string]any{"inspector": inspector})
+		return
+	case "query-range":
+		var request queryplan.Request
+		if decodeJSON(w, r, &request) {
+			response, err = h.Service.ExecuteRange(r.Context(), request)
+		}
+	case "query":
+		var request InstantRequest
+		if decodeJSON(w, r, &request) {
+			response, err = h.Service.ExecuteInstant(r.Context(), request)
+		}
+	default:
+		http.NotFound(w, r)
+		return
+	}
+	if err != nil {
+		writeQueryError(w, r, err)
+		return
+	}
+	w.Header().Set("Content-Type", "application/json")
+	_ = json.NewEncoder(w).Encode(response)
+}
+
+func decodeJSON(w http.ResponseWriter, r *http.Request, destination any) bool {
+	body, readErr := io.ReadAll(io.LimitReader(r.Body, maxRequestBody+1))
+	if readErr != nil || len(body) > maxRequestBody {
+		problem.Write(w, r, http.StatusRequestEntityTooLarge, "QUERY_BODY_LIMIT", "Query body too large", "The metric query body exceeds the allowed size.", nil)
+		return false
+	}
+	decoder := json.NewDecoder(bytes.NewReader(body))
+	decoder.DisallowUnknownFields()
+	if err := decoder.Decode(destination); err != nil {
+		problem.Write(w, r, http.StatusBadRequest, "QUERY_BODY_INVALID", "Invalid query body", "The metric query body is invalid.", nil)
+		return false
+	}
+	var extra any
+	if err := decoder.Decode(&extra); err != io.EOF {
+		problem.Write(w, r, http.StatusBadRequest, "QUERY_BODY_INVALID", "Invalid query body", "The metric query body contains trailing data.", nil)
+		return false
+	}
+	return true
+}
+
+func writeQueryError(w http.ResponseWriter, r *http.Request, err error) {
+	if errors.Is(err, ErrInspectorUnauthorized) {
+		problem.Write(w, r, http.StatusForbidden, "QUERY_INSPECTOR_FORBIDDEN", "Query inspector forbidden", "The query inspector requires operate permission.", nil)
+		return
+	}
+	if errors.Is(err, context.Canceled) {
+		return
+	}
+	var sourceErr sourceError
+	if errors.Is(err, ErrSourceUnavailable) || errors.As(err, &sourceErr) {
+		problem.Write(w, r, http.StatusServiceUnavailable, "QUERY_SOURCE_UNAVAILABLE", "Metric source unavailable", "The metric source could not be queried.", nil)
+		return
+	}
+	var planError queryplan.Error
+	if errors.As(err, &planError) {
+		status := http.StatusUnprocessableEntity
+		if planError.Code == queryplan.ErrUnauthorized.Code {
+			status = http.StatusUnauthorized
+		}
+		problem.Write(w, r, status, planError.Code, "Metric query rejected", planError.Detail, map[string]string{"field": planError.Field})
+		return
+	}
+	var bindingError promqlbinding.Error
+	if errors.As(err, &bindingError) {
+		status := http.StatusUnprocessableEntity
+		if bindingError.Code == "PROMQL_RAW_UNAUTHORIZED" {
+			status = http.StatusForbidden
+		}
+		problem.Write(w, r, status, bindingError.Code, "Metric query rejected", bindingError.Detail, map[string]string{"field": bindingError.Field})
+		return
+	}
+	problem.Write(w, r, http.StatusServiceUnavailable, "QUERY_UNAVAILABLE", "Metric query unavailable", "The metric query could not be completed.", nil)
+}