prometheus/web/api/legacy/query.go

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// Copyright 2013 The Prometheus Authors
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package legacy
import (
"encoding/json"
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"errors"
"fmt"
"io"
"net/http"
"net/url"
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"sort"
"strconv"
"time"
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"github.com/prometheus/common/log"
"github.com/prometheus/common/model"
)
// Enables cross-site script calls.
func setAccessControlHeaders(w http.ResponseWriter) {
w.Header().Set("Access-Control-Allow-Headers", "Accept, Authorization, Content-Type, Origin")
w.Header().Set("Access-Control-Allow-Methods", "GET, OPTIONS")
w.Header().Set("Access-Control-Allow-Origin", "*")
w.Header().Set("Access-Control-Expose-Headers", "Date")
}
func httpJSONError(w http.ResponseWriter, err error, code int) {
w.WriteHeader(code)
errorJSON(w, err)
}
func parseTimestampOrNow(t string, now model.Time) (model.Time, error) {
if t == "" {
return now, nil
}
tFloat, err := strconv.ParseFloat(t, 64)
if err != nil {
return 0, err
}
return model.TimeFromUnixNano(int64(tFloat * float64(time.Second/time.Nanosecond))), nil
}
func parseDuration(d string) (time.Duration, error) {
dFloat, err := strconv.ParseFloat(d, 64)
if err != nil {
return 0, err
}
return time.Duration(dFloat * float64(time.Second/time.Nanosecond)), nil
}
// Options handles OPTIONS requests to /api/... endpoints.
func (api *API) Options(w http.ResponseWriter, r *http.Request) {
setAccessControlHeaders(w)
w.WriteHeader(http.StatusNoContent)
}
// Query handles the /api/query endpoint.
func (api *API) Query(w http.ResponseWriter, r *http.Request) {
setAccessControlHeaders(w)
w.Header().Set("Content-Type", "application/json")
params := getQueryParams(r)
expr := params.Get("expr")
timestamp, err := parseTimestampOrNow(params.Get("timestamp"), api.Now())
if err != nil {
httpJSONError(w, fmt.Errorf("invalid query timestamp %s", err), http.StatusBadRequest)
return
}
query, err := api.QueryEngine.NewInstantQuery(expr, timestamp)
if err != nil {
httpJSONError(w, err, http.StatusOK)
return
}
res := query.Exec()
if res.Err != nil {
httpJSONError(w, res.Err, http.StatusOK)
return
}
log.Debugf("Instant query: %s\nQuery stats:\n%s\n", expr, query.Stats())
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if vec, ok := res.Value.(model.Vector); ok {
respondJSON(w, plainVec(vec))
return
}
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if sca, ok := res.Value.(*model.Scalar); ok {
respondJSON(w, (*plainScalar)(sca))
return
}
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if str, ok := res.Value.(*model.String); ok {
respondJSON(w, (*plainString)(str))
return
}
respondJSON(w, res.Value)
}
// plainVec is an indirection that hides the original MarshalJSON method
// which does not fit the response format for the legacy API.
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type plainVec model.Vector
func (pv plainVec) MarshalJSON() ([]byte, error) {
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type plainSmpl model.Sample
v := make([]*plainSmpl, len(pv))
for i, sv := range pv {
v[i] = (*plainSmpl)(sv)
}
return json.Marshal(&v)
}
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func (pv plainVec) Type() model.ValueType {
return model.ValVector
}
func (pv plainVec) String() string {
return ""
}
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// plainScalar is an indirection that hides the original MarshalJSON method
// which does not fit the response format for the legacy API.
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type plainScalar model.Scalar
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func (ps plainScalar) MarshalJSON() ([]byte, error) {
s := strconv.FormatFloat(float64(ps.Value), 'f', -1, 64)
return json.Marshal(&s)
}
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func (plainScalar) Type() model.ValueType {
return model.ValScalar
}
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func (plainScalar) String() string {
return ""
}
// plainString is an indirection that hides the original MarshalJSON method
// which does not fit the response format for the legacy API.
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type plainString model.String
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func (pv plainString) Type() model.ValueType {
return model.ValString
}
func (pv plainString) String() string {
return ""
}
// QueryRange handles the /api/query_range endpoint.
func (api *API) QueryRange(w http.ResponseWriter, r *http.Request) {
setAccessControlHeaders(w)
w.Header().Set("Content-Type", "application/json")
params := getQueryParams(r)
expr := params.Get("expr")
duration, err := parseDuration(params.Get("range"))
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if err != nil {
httpJSONError(w, fmt.Errorf("invalid query range: %s", err), http.StatusBadRequest)
return
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}
step, err := parseDuration(params.Get("step"))
if err != nil {
httpJSONError(w, fmt.Errorf("invalid query resolution: %s", err), http.StatusBadRequest)
return
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}
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end, err := parseTimestampOrNow(params.Get("end"), api.Now())
if err != nil {
httpJSONError(w, fmt.Errorf("invalid query timestamp: %s", err), http.StatusBadRequest)
return
}
// TODO(julius): Remove this special-case handling a while after PromDash and
// other API consumers have been changed to no longer set "end=0" for setting
// the current time as the end time. Instead, the "end" parameter should
// simply be omitted or set to an empty string for that case.
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if end == 0 {
end = api.Now()
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}
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// For safety, limit the number of returned points per timeseries.
// This is sufficient for 60s resolution for a week or 1h resolution for a year.
if duration/step > 11000 {
err := errors.New("exceeded maximum resolution of 11,000 points per timeseries. Try decreasing the query resolution (?step=XX)")
httpJSONError(w, err, http.StatusBadRequest)
return
}
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// Align the start to step "tick" boundary.
end = end.Add(-time.Duration(end.UnixNano() % int64(step)))
start := end.Add(-duration)
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query, err := api.QueryEngine.NewRangeQuery(expr, start, end, step)
if err != nil {
httpJSONError(w, err, http.StatusOK)
return
}
matrix, err := query.Exec().Matrix()
if err != nil {
httpJSONError(w, err, http.StatusOK)
return
}
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log.Debugf("Range query: %s\nQuery stats:\n%s\n", expr, query.Stats())
respondJSON(w, matrix)
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}
// Metrics handles the /api/metrics endpoint.
func (api *API) Metrics(w http.ResponseWriter, r *http.Request) {
setAccessControlHeaders(w)
w.Header().Set("Content-Type", "application/json")
metricNames := api.Storage.LabelValuesForLabelName(model.MetricNameLabel)
sort.Sort(metricNames)
resultBytes, err := json.Marshal(metricNames)
if err != nil {
log.Error("Error marshalling metric names: ", err)
httpJSONError(w, fmt.Errorf("error marshalling metric names: %s", err), http.StatusInternalServerError)
return
}
w.Write(resultBytes)
}
// GetQueryParams calls r.ParseForm and returns r.Form.
func getQueryParams(r *http.Request) url.Values {
r.ParseForm()
return r.Form
}
var jsonFormatVersion = 1
// ErrorJSON writes the given error JSON-formatted to w.
func errorJSON(w io.Writer, err error) error {
data := struct {
Type string `json:"type"`
Value string `json:"value"`
Version int `json:"version"`
}{
Type: "error",
Value: err.Error(),
Version: jsonFormatVersion,
}
enc := json.NewEncoder(w)
return enc.Encode(data)
}
// RespondJSON converts the given data value to JSON and writes it to w.
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func respondJSON(w io.Writer, val model.Value) error {
data := struct {
Type string `json:"type"`
Value interface{} `json:"value"`
Version int `json:"version"`
}{
Type: val.Type().String(),
Value: val,
Version: jsonFormatVersion,
}
// TODO(fabxc): Adding MarshalJSON to promql.Values might be a good idea.
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if sc, ok := val.(*model.Scalar); ok {
data.Value = sc.Value
}
enc := json.NewEncoder(w)
return enc.Encode(data)
}