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api.go
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api.go
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// Copyright 2016 Circonus, Inc. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package api
import (
"bytes"
"context"
crand "crypto/rand"
"crypto/tls"
"crypto/x509"
"errors"
"fmt"
"io/ioutil"
"log"
"math"
"math/big"
"math/rand"
"net"
"net/http"
"net/url"
"os"
"strings"
"sync"
"time"
"github.com/hashicorp/go-retryablehttp"
)
func init() {
n, err := crand.Int(crand.Reader, big.NewInt(math.MaxInt64))
if err != nil {
rand.Seed(time.Now().UTC().UnixNano())
return
}
rand.Seed(n.Int64())
}
const (
// a few sensible defaults
defaultAPIURL = "https://api.circonus.com/v2"
defaultAPIApp = "circonus-gometrics"
minRetryWait = 1 * time.Second
maxRetryWait = 15 * time.Second
maxRetries = 4 // equating to 1 + maxRetries total attempts
)
// TokenKeyType - Circonus API Token key
type TokenKeyType string
// TokenAppType - Circonus API Token app name
type TokenAppType string
// TokenAccountIDType - Circonus API Token account id
type TokenAccountIDType string
// CIDType Circonus object cid
type CIDType *string
// IDType Circonus object id
type IDType int
// URLType submission url type
type URLType string
// SearchQueryType search query (see: https://login.circonus.com/resources/api#searching)
type SearchQueryType string
// SearchFilterType search filter (see: https://login.circonus.com/resources/api#filtering)
type SearchFilterType map[string][]string
// TagType search/select/custom tag(s) type
type TagType []string
// Config options for Circonus API
type Config struct {
// URL defines the API URL - default https://api.circonus.com/v2/
URL string
// TokenKey defines the key to use when communicating with the API
TokenKey string
// TokenApp defines the app to use when communicating with the API
TokenApp string
TokenAccountID string
// CACert deprecating, use TLSConfig instead
CACert *x509.CertPool
// TLSConfig defines a custom tls configuration to use when communicating with the API
TLSConfig *tls.Config
Log *log.Logger
Debug bool
}
// API Circonus API
type API struct {
apiURL *url.URL
key TokenKeyType
app TokenAppType
accountID TokenAccountIDType
caCert *x509.CertPool
tlsConfig *tls.Config
Debug bool
Log *log.Logger
useExponentialBackoff bool
useExponentialBackoffmu sync.Mutex
}
// NewClient returns a new Circonus API (alias for New)
func NewClient(ac *Config) (*API, error) {
return New(ac)
}
// NewAPI returns a new Circonus API (alias for New)
func NewAPI(ac *Config) (*API, error) {
return New(ac)
}
// New returns a new Circonus API
func New(ac *Config) (*API, error) {
if ac == nil {
return nil, errors.New("Invalid API configuration (nil)")
}
key := TokenKeyType(ac.TokenKey)
if key == "" {
return nil, errors.New("API Token is required")
}
app := TokenAppType(ac.TokenApp)
if app == "" {
app = defaultAPIApp
}
acctID := TokenAccountIDType(ac.TokenAccountID)
au := string(ac.URL)
if au == "" {
au = defaultAPIURL
}
if !strings.Contains(au, "/") {
// if just a hostname is passed, ASSume "https" and a path prefix of "/v2"
au = fmt.Sprintf("https://%s/v2", ac.URL)
}
if last := len(au) - 1; last >= 0 && au[last] == '/' {
// strip off trailing '/'
au = au[:last]
}
apiURL, err := url.Parse(au)
if err != nil {
return nil, err
}
a := &API{
apiURL: apiURL,
key: key,
app: app,
accountID: acctID,
caCert: ac.CACert,
tlsConfig: ac.TLSConfig,
Debug: ac.Debug,
Log: ac.Log,
useExponentialBackoff: false,
}
a.Debug = ac.Debug
a.Log = ac.Log
if a.Debug && a.Log == nil {
a.Log = log.New(os.Stderr, "", log.LstdFlags)
}
if a.Log == nil {
a.Log = log.New(ioutil.Discard, "", log.LstdFlags)
}
return a, nil
}
// EnableExponentialBackoff enables use of exponential backoff for next API call(s)
// and use exponential backoff for all API calls until exponential backoff is disabled.
func (a *API) EnableExponentialBackoff() {
a.useExponentialBackoffmu.Lock()
a.useExponentialBackoff = true
a.useExponentialBackoffmu.Unlock()
}
// DisableExponentialBackoff disables use of exponential backoff. If a request using
// exponential backoff is currently running, it will stop using exponential backoff
// on its next iteration (if needed).
func (a *API) DisableExponentialBackoff() {
a.useExponentialBackoffmu.Lock()
a.useExponentialBackoff = false
a.useExponentialBackoffmu.Unlock()
}
// Get API request
func (a *API) Get(reqPath string) ([]byte, error) {
return a.apiRequest("GET", reqPath, nil)
}
// Delete API request
func (a *API) Delete(reqPath string) ([]byte, error) {
return a.apiRequest("DELETE", reqPath, nil)
}
// Post API request
func (a *API) Post(reqPath string, data []byte) ([]byte, error) {
return a.apiRequest("POST", reqPath, data)
}
// Put API request
func (a *API) Put(reqPath string, data []byte) ([]byte, error) {
return a.apiRequest("PUT", reqPath, data)
}
func backoff(interval uint) float64 {
return math.Floor(((float64(interval) * (1 + rand.Float64())) / 2) + .5)
}
// apiRequest manages retry strategy for exponential backoffs
func (a *API) apiRequest(reqMethod string, reqPath string, data []byte) ([]byte, error) {
backoffs := []uint{2, 4, 8, 16, 32}
attempts := 0
success := false
var result []byte
var err error
for !success {
result, err = a.apiCall(reqMethod, reqPath, data)
if err == nil {
success = true
}
// break and return error if not using exponential backoff
if err != nil {
if !a.useExponentialBackoff {
break
}
if strings.Contains(err.Error(), "code 403") {
break
}
}
if !success {
var wait float64
if attempts >= len(backoffs) {
wait = backoff(backoffs[len(backoffs)-1])
} else {
wait = backoff(backoffs[attempts])
}
attempts++
a.Log.Printf("[WARN] API call failed %s, retrying in %d seconds.\n", err.Error(), uint(wait))
time.Sleep(time.Duration(wait) * time.Second)
}
}
return result, err
}
// apiCall call Circonus API
func (a *API) apiCall(reqMethod string, reqPath string, data []byte) ([]byte, error) {
reqURL := a.apiURL.String()
if reqPath == "" {
return nil, errors.New("Invalid URL path")
}
if reqPath[:1] != "/" {
reqURL += "/"
}
if len(reqPath) >= 3 && reqPath[:3] == "/v2" {
reqURL += reqPath[3:]
} else {
reqURL += reqPath
}
// keep last HTTP error in the event of retry failure
var lastHTTPError error
retryPolicy := func(ctx context.Context, resp *http.Response, err error) (bool, error) {
if ctxErr := ctx.Err(); ctxErr != nil {
return false, ctxErr
}
if err != nil {
lastHTTPError = err
return true, err
}
// Check the response code. We retry on 500-range responses to allow
// the server time to recover, as 500's are typically not permanent
// errors and may relate to outages on the server side. This will catch
// invalid response codes as well, like 0 and 999.
// Retry on 429 (rate limit) as well.
if resp.StatusCode == 0 || // wtf?!
resp.StatusCode >= 500 || // rutroh
resp.StatusCode == 429 { // rate limit
body, readErr := ioutil.ReadAll(resp.Body)
if readErr != nil {
lastHTTPError = fmt.Errorf("- response: %d %s", resp.StatusCode, readErr.Error())
} else {
lastHTTPError = fmt.Errorf("- response: %d %s", resp.StatusCode, strings.TrimSpace(string(body)))
}
return true, nil
}
return false, nil
}
dataReader := bytes.NewReader(data)
req, err := retryablehttp.NewRequest(reqMethod, reqURL, dataReader)
if err != nil {
return nil, fmt.Errorf("[ERROR] creating API request: %s %+v", reqURL, err)
}
req.Header.Add("Accept", "application/json")
req.Header.Add("X-Circonus-Auth-Token", string(a.key))
req.Header.Add("X-Circonus-App-Name", string(a.app))
if string(a.accountID) != "" {
req.Header.Add("X-Circonus-Account-ID", string(a.accountID))
}
client := retryablehttp.NewClient()
if a.apiURL.Scheme == "https" {
var tlscfg *tls.Config
if a.tlsConfig != nil { // preference full custom tls config
tlscfg = a.tlsConfig
} else if a.caCert != nil {
tlscfg = &tls.Config{RootCAs: a.caCert}
}
client.HTTPClient.Transport = &http.Transport{
Proxy: http.ProxyFromEnvironment,
Dial: (&net.Dialer{
Timeout: 30 * time.Second,
KeepAlive: 30 * time.Second,
}).Dial,
TLSHandshakeTimeout: 10 * time.Second,
TLSClientConfig: tlscfg,
DisableKeepAlives: true,
MaxIdleConnsPerHost: -1,
DisableCompression: true,
}
} else {
client.HTTPClient.Transport = &http.Transport{
Proxy: http.ProxyFromEnvironment,
Dial: (&net.Dialer{
Timeout: 30 * time.Second,
KeepAlive: 30 * time.Second,
}).Dial,
TLSHandshakeTimeout: 10 * time.Second,
DisableKeepAlives: true,
MaxIdleConnsPerHost: -1,
DisableCompression: true,
}
}
a.useExponentialBackoffmu.Lock()
eb := a.useExponentialBackoff
a.useExponentialBackoffmu.Unlock()
if eb {
// limit to one request if using exponential backoff
client.RetryWaitMin = 1
client.RetryWaitMax = 2
client.RetryMax = 0
} else {
client.RetryWaitMin = minRetryWait
client.RetryWaitMax = maxRetryWait
client.RetryMax = maxRetries
}
// retryablehttp only groks log or no log
if a.Debug {
client.Logger = a.Log
} else {
client.Logger = log.New(ioutil.Discard, "", log.LstdFlags)
}
client.CheckRetry = retryPolicy
resp, err := client.Do(req)
if err != nil {
if lastHTTPError != nil {
return nil, lastHTTPError
}
return nil, fmt.Errorf("[ERROR] %s: %+v", reqURL, err)
}
defer resp.Body.Close()
body, err := ioutil.ReadAll(resp.Body)
if err != nil {
return nil, fmt.Errorf("[ERROR] reading response %+v", err)
}
if resp.StatusCode < 200 || resp.StatusCode >= 300 {
msg := fmt.Sprintf("API response code %d: %s", resp.StatusCode, string(body))
if a.Debug {
a.Log.Printf("[DEBUG] %s\n", msg)
}
return nil, fmt.Errorf("[ERROR] %s", msg)
}
return body, nil
}