client_golang/api/prometheus/api.go

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// Copyright 2015 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 prometheus provides bindings to the Prometheus HTTP API:
// http://prometheus.io/docs/querying/api/
package prometheus
import (
"encoding/json"
"fmt"
"io/ioutil"
"net"
"net/http"
"net/url"
"path"
"strconv"
"strings"
"time"
"github.com/prometheus/common/model"
"golang.org/x/net/context"
"golang.org/x/net/context/ctxhttp"
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)
const (
statusAPIError = 422
apiPrefix = "/api/v1"
epQuery = "/query"
epQueryRange = "/query_range"
epLabelValues = "/label/:name/values"
epSeries = "/series"
)
// ErrorType models the different API error types.
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type ErrorType string
// Possible values for ErrorType.
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const (
ErrBadData ErrorType = "bad_data"
ErrTimeout = "timeout"
ErrCanceled = "canceled"
ErrExec = "execution"
ErrBadResponse = "bad_response"
)
// Error is an error returned by the API.
type Error struct {
Type ErrorType
Msg string
}
func (e *Error) Error() string {
return fmt.Sprintf("%s: %s", e.Type, e.Msg)
}
// CancelableTransport is like net.Transport but provides
// per-request cancelation functionality.
type CancelableTransport interface {
http.RoundTripper
CancelRequest(req *http.Request)
}
// DefaultTransport is used if no Transport is set in Config.
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var DefaultTransport CancelableTransport = &http.Transport{
Proxy: http.ProxyFromEnvironment,
Dial: (&net.Dialer{
Timeout: 30 * time.Second,
KeepAlive: 30 * time.Second,
}).Dial,
TLSHandshakeTimeout: 10 * time.Second,
}
// Config defines configuration parameters for a new client.
type Config struct {
// The address of the Prometheus to connect to.
Address string
// Transport is used by the Client to drive HTTP requests. If not
// provided, DefaultTransport will be used.
Transport CancelableTransport
}
func (cfg *Config) transport() CancelableTransport {
if cfg.Transport == nil {
return DefaultTransport
}
return cfg.Transport
}
// Client is the interface for an API client.
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type Client interface {
url(ep string, args map[string]string) *url.URL
do(context.Context, *http.Request) (*http.Response, []byte, error)
}
// New returns a new Client.
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//
// It is safe to use the returned Client from multiple goroutines.
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func New(cfg Config) (Client, error) {
u, err := url.Parse(cfg.Address)
if err != nil {
return nil, err
}
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u.Path = strings.TrimRight(u.Path, "/") + apiPrefix
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return &httpClient{
endpoint: u,
transport: cfg.transport(),
}, nil
}
type httpClient struct {
endpoint *url.URL
transport CancelableTransport
}
func (c *httpClient) url(ep string, args map[string]string) *url.URL {
p := path.Join(c.endpoint.Path, ep)
for arg, val := range args {
arg = ":" + arg
p = strings.Replace(p, arg, val, -1)
}
u := *c.endpoint
u.Path = p
return &u
}
func (c *httpClient) do(ctx context.Context, req *http.Request) (*http.Response, []byte, error) {
resp, err := ctxhttp.Do(ctx, &http.Client{Transport: c.transport}, req)
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defer func() {
if resp != nil {
resp.Body.Close()
}
}()
if err != nil {
return nil, nil, err
}
var body []byte
done := make(chan struct{})
go func() {
body, err = ioutil.ReadAll(resp.Body)
close(done)
}()
select {
case <-ctx.Done():
err = resp.Body.Close()
<-done
if err == nil {
err = ctx.Err()
}
case <-done:
}
return resp, body, err
}
// apiClient wraps a regular client and processes successful API responses.
// Successful also includes responses that errored at the API level.
type apiClient struct {
Client
}
type apiResponse struct {
Status string `json:"status"`
Data json.RawMessage `json:"data"`
ErrorType ErrorType `json:"errorType"`
Error string `json:"error"`
}
func (c apiClient) do(ctx context.Context, req *http.Request) (*http.Response, []byte, error) {
resp, body, err := c.Client.do(ctx, req)
if err != nil {
return resp, body, err
}
code := resp.StatusCode
if code/100 != 2 && code != statusAPIError {
return resp, body, &Error{
Type: ErrBadResponse,
Msg: fmt.Sprintf("bad response code %d", resp.StatusCode),
}
}
var result apiResponse
if err = json.Unmarshal(body, &result); err != nil {
return resp, body, &Error{
Type: ErrBadResponse,
Msg: err.Error(),
}
}
if (code == statusAPIError) != (result.Status == "error") {
err = &Error{
Type: ErrBadResponse,
Msg: "inconsistent body for response code",
}
}
if code == statusAPIError && result.Status == "error" {
err = &Error{
Type: result.ErrorType,
Msg: result.Error,
}
}
return resp, []byte(result.Data), err
}
// Range represents a sliced time range.
type Range struct {
// The boundaries of the time range.
Start, End time.Time
// The maximum time between two slices within the boundaries.
Step time.Duration
}
// queryResult contains result data for a query.
type queryResult struct {
Type model.ValueType `json:"resultType"`
Result interface{} `json:"result"`
// The decoded value.
v model.Value
}
func (qr *queryResult) UnmarshalJSON(b []byte) error {
v := struct {
Type model.ValueType `json:"resultType"`
Result json.RawMessage `json:"result"`
}{}
err := json.Unmarshal(b, &v)
if err != nil {
return err
}
switch v.Type {
case model.ValScalar:
var sv model.Scalar
err = json.Unmarshal(v.Result, &sv)
qr.v = &sv
case model.ValVector:
var vv model.Vector
err = json.Unmarshal(v.Result, &vv)
qr.v = vv
case model.ValMatrix:
var mv model.Matrix
err = json.Unmarshal(v.Result, &mv)
qr.v = mv
default:
err = fmt.Errorf("unexpected value type %q", v.Type)
}
return err
}
// QueryAPI provides bindings the Prometheus's query API.
type QueryAPI interface {
// Query performs a query for the given time.
Query(ctx context.Context, query string, ts time.Time) (model.Value, error)
// Query performs a query for the given range.
QueryRange(ctx context.Context, query string, r Range) (model.Value, error)
}
// NewQueryAPI returns a new QueryAPI for the client.
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//
// It is safe to use the returned QueryAPI from multiple goroutines.
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func NewQueryAPI(c Client) QueryAPI {
return &httpQueryAPI{client: apiClient{c}}
}
type httpQueryAPI struct {
client Client
}
func (h *httpQueryAPI) Query(ctx context.Context, query string, ts time.Time) (model.Value, error) {
u := h.client.url(epQuery, nil)
q := u.Query()
q.Set("query", query)
q.Set("time", ts.Format(time.RFC3339Nano))
u.RawQuery = q.Encode()
req, _ := http.NewRequest("GET", u.String(), nil)
_, body, err := h.client.do(ctx, req)
if err != nil {
return nil, err
}
var qres queryResult
err = json.Unmarshal(body, &qres)
return model.Value(qres.v), err
}
func (h *httpQueryAPI) QueryRange(ctx context.Context, query string, r Range) (model.Value, error) {
u := h.client.url(epQueryRange, nil)
q := u.Query()
var (
start = r.Start.Format(time.RFC3339Nano)
end = r.End.Format(time.RFC3339Nano)
step = strconv.FormatFloat(r.Step.Seconds(), 'f', 3, 64)
)
q.Set("query", query)
q.Set("start", start)
q.Set("end", end)
q.Set("step", step)
u.RawQuery = q.Encode()
req, _ := http.NewRequest("GET", u.String(), nil)
_, body, err := h.client.do(ctx, req)
if err != nil {
return nil, err
}
var qres queryResult
err = json.Unmarshal(body, &qres)
return model.Value(qres.v), err
}