From de6d2c524430287c699aaa898c1325da6afea539 Mon Sep 17 00:00:00 2001 From: Niall Sheridan Date: Wed, 20 Jun 2018 22:39:07 +0100 Subject: Update dependencies --- .../hashicorp/go-retryablehttp/client.go | 487 +++++++++++++++++++++ 1 file changed, 487 insertions(+) create mode 100644 vendor/github.com/hashicorp/go-retryablehttp/client.go (limited to 'vendor/github.com/hashicorp/go-retryablehttp/client.go') diff --git a/vendor/github.com/hashicorp/go-retryablehttp/client.go b/vendor/github.com/hashicorp/go-retryablehttp/client.go new file mode 100644 index 0000000..c016939 --- /dev/null +++ b/vendor/github.com/hashicorp/go-retryablehttp/client.go @@ -0,0 +1,487 @@ +// The retryablehttp package provides a familiar HTTP client interface with +// automatic retries and exponential backoff. It is a thin wrapper over the +// standard net/http client library and exposes nearly the same public API. +// This makes retryablehttp very easy to drop into existing programs. +// +// retryablehttp performs automatic retries under certain conditions. Mainly, if +// an error is returned by the client (connection errors etc), or if a 500-range +// response is received, then a retry is invoked. Otherwise, the response is +// returned and left to the caller to interpret. +// +// Requests which take a request body should provide a non-nil function +// parameter. The best choice is to provide either a function satisfying +// ReaderFunc which provides multiple io.Readers in an efficient manner, a +// *bytes.Buffer (the underlying raw byte slice will be used) or a raw byte +// slice. As it is a reference type, and we will wrap it as needed by readers, +// we can efficiently re-use the request body without needing to copy it. If an +// io.Reader (such as a *bytes.Reader) is provided, the full body will be read +// prior to the first request, and will be efficiently re-used for any retries. +// ReadSeeker can be used, but some users have observed occasional data races +// between the net/http library and the Seek functionality of some +// implementations of ReadSeeker, so should be avoided if possible. +package retryablehttp + +import ( + "bytes" + "fmt" + "io" + "io/ioutil" + "log" + "math" + "math/rand" + "net/http" + "net/url" + "os" + "strings" + "time" + + "github.com/hashicorp/go-cleanhttp" +) + +var ( + // Default retry configuration + defaultRetryWaitMin = 1 * time.Second + defaultRetryWaitMax = 30 * time.Second + defaultRetryMax = 4 + + // defaultClient is used for performing requests without explicitly making + // a new client. It is purposely private to avoid modifications. + defaultClient = NewClient() + + // We need to consume response bodies to maintain http connections, but + // limit the size we consume to respReadLimit. + respReadLimit = int64(4096) +) + +// ReaderFunc is the type of function that can be given natively to NewRequest +type ReaderFunc func() (io.Reader, error) + +// LenReader is an interface implemented by many in-memory io.Reader's. Used +// for automatically sending the right Content-Length header when possible. +type LenReader interface { + Len() int +} + +// Request wraps the metadata needed to create HTTP requests. +type Request struct { + // body is a seekable reader over the request body payload. This is + // used to rewind the request data in between retries. + body ReaderFunc + + // Embed an HTTP request directly. This makes a *Request act exactly + // like an *http.Request so that all meta methods are supported. + *http.Request +} + +// NewRequest creates a new wrapped request. +func NewRequest(method, url string, rawBody interface{}) (*Request, error) { + var err error + var body ReaderFunc + var contentLength int64 + + if rawBody != nil { + switch rawBody.(type) { + // If they gave us a function already, great! Use it. + case ReaderFunc: + body = rawBody.(ReaderFunc) + tmp, err := body() + if err != nil { + return nil, err + } + if lr, ok := tmp.(LenReader); ok { + contentLength = int64(lr.Len()) + } + if c, ok := tmp.(io.Closer); ok { + c.Close() + } + + case func() (io.Reader, error): + body = rawBody.(func() (io.Reader, error)) + tmp, err := body() + if err != nil { + return nil, err + } + if lr, ok := tmp.(LenReader); ok { + contentLength = int64(lr.Len()) + } + if c, ok := tmp.(io.Closer); ok { + c.Close() + } + + // If a regular byte slice, we can read it over and over via new + // readers + case []byte: + buf := rawBody.([]byte) + body = func() (io.Reader, error) { + return bytes.NewReader(buf), nil + } + contentLength = int64(len(buf)) + + // If a bytes.Buffer we can read the underlying byte slice over and + // over + case *bytes.Buffer: + buf := rawBody.(*bytes.Buffer) + body = func() (io.Reader, error) { + return bytes.NewReader(buf.Bytes()), nil + } + contentLength = int64(buf.Len()) + + // We prioritize *bytes.Reader here because we don't really want to + // deal with it seeking so want it to match here instead of the + // io.ReadSeeker case. + case *bytes.Reader: + buf, err := ioutil.ReadAll(rawBody.(*bytes.Reader)) + if err != nil { + return nil, err + } + body = func() (io.Reader, error) { + return bytes.NewReader(buf), nil + } + contentLength = int64(len(buf)) + + // Compat case + case io.ReadSeeker: + raw := rawBody.(io.ReadSeeker) + body = func() (io.Reader, error) { + raw.Seek(0, 0) + return ioutil.NopCloser(raw), nil + } + if lr, ok := raw.(LenReader); ok { + contentLength = int64(lr.Len()) + } + + // Read all in so we can reset + case io.Reader: + buf, err := ioutil.ReadAll(rawBody.(io.Reader)) + if err != nil { + return nil, err + } + body = func() (io.Reader, error) { + return bytes.NewReader(buf), nil + } + contentLength = int64(len(buf)) + + default: + return nil, fmt.Errorf("cannot handle type %T", rawBody) + } + } + + httpReq, err := http.NewRequest(method, url, nil) + if err != nil { + return nil, err + } + httpReq.ContentLength = contentLength + + return &Request{body, httpReq}, nil +} + +// RequestLogHook allows a function to run before each retry. The HTTP +// request which will be made, and the retry number (0 for the initial +// request) are available to users. The internal logger is exposed to +// consumers. +type RequestLogHook func(*log.Logger, *http.Request, int) + +// ResponseLogHook is like RequestLogHook, but allows running a function +// on each HTTP response. This function will be invoked at the end of +// every HTTP request executed, regardless of whether a subsequent retry +// needs to be performed or not. If the response body is read or closed +// from this method, this will affect the response returned from Do(). +type ResponseLogHook func(*log.Logger, *http.Response) + +// CheckRetry specifies a policy for handling retries. It is called +// following each request with the response and error values returned by +// the http.Client. If CheckRetry returns false, the Client stops retrying +// and returns the response to the caller. If CheckRetry returns an error, +// that error value is returned in lieu of the error from the request. The +// Client will close any response body when retrying, but if the retry is +// aborted it is up to the CheckResponse callback to properly close any +// response body before returning. +type CheckRetry func(resp *http.Response, err error) (bool, error) + +// Backoff specifies a policy for how long to wait between retries. +// It is called after a failing request to determine the amount of time +// that should pass before trying again. +type Backoff func(min, max time.Duration, attemptNum int, resp *http.Response) time.Duration + +// ErrorHandler is called if retries are expired, containing the last status +// from the http library. If not specified, default behavior for the library is +// to close the body and return an error indicating how many tries were +// attempted. If overriding this, be sure to close the body if needed. +type ErrorHandler func(resp *http.Response, err error, numTries int) (*http.Response, error) + +// Client is used to make HTTP requests. It adds additional functionality +// like automatic retries to tolerate minor outages. +type Client struct { + HTTPClient *http.Client // Internal HTTP client. + Logger *log.Logger // Customer logger instance. + + RetryWaitMin time.Duration // Minimum time to wait + RetryWaitMax time.Duration // Maximum time to wait + RetryMax int // Maximum number of retries + + // RequestLogHook allows a user-supplied function to be called + // before each retry. + RequestLogHook RequestLogHook + + // ResponseLogHook allows a user-supplied function to be called + // with the response from each HTTP request executed. + ResponseLogHook ResponseLogHook + + // CheckRetry specifies the policy for handling retries, and is called + // after each request. The default policy is DefaultRetryPolicy. + CheckRetry CheckRetry + + // Backoff specifies the policy for how long to wait between retries + Backoff Backoff + + // ErrorHandler specifies the custom error handler to use, if any + ErrorHandler ErrorHandler +} + +// NewClient creates a new Client with default settings. +func NewClient() *Client { + return &Client{ + HTTPClient: cleanhttp.DefaultClient(), + Logger: log.New(os.Stderr, "", log.LstdFlags), + RetryWaitMin: defaultRetryWaitMin, + RetryWaitMax: defaultRetryWaitMax, + RetryMax: defaultRetryMax, + CheckRetry: DefaultRetryPolicy, + Backoff: DefaultBackoff, + } +} + +// DefaultRetryPolicy provides a default callback for Client.CheckRetry, which +// will retry on connection errors and server errors. +func DefaultRetryPolicy(resp *http.Response, err error) (bool, error) { + if err != nil { + 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. + if resp.StatusCode == 0 || (resp.StatusCode >= 500 && resp.StatusCode != 501) { + return true, nil + } + + return false, nil +} + +// DefaultBackoff provides a default callback for Client.Backoff which +// will perform exponential backoff based on the attempt number and limited +// by the provided minimum and maximum durations. +func DefaultBackoff(min, max time.Duration, attemptNum int, resp *http.Response) time.Duration { + mult := math.Pow(2, float64(attemptNum)) * float64(min) + sleep := time.Duration(mult) + if float64(sleep) != mult || sleep > max { + sleep = max + } + return sleep +} + +// LinearJitterBackoff provides a callback for Client.Backoff which will +// perform linear backoff based on the attempt number and with jitter to +// prevent a thundering herd. +// +// min and max here are *not* absolute values. The number to be multipled by +// the attempt number will be chosen at random from between them, thus they are +// bounding the jitter. +// +// For instance: +// * To get strictly linear backoff of one second increasing each retry, set +// both to one second (1s, 2s, 3s, 4s, ...) +// * To get a small amount of jitter centered around one second increasing each +// retry, set to around one second, such as a min of 800ms and max of 1200ms +// (892ms, 2102ms, 2945ms, 4312ms, ...) +// * To get extreme jitter, set to a very wide spread, such as a min of 100ms +// and a max of 20s (15382ms, 292ms, 51321ms, 35234ms, ...) +func LinearJitterBackoff(min, max time.Duration, attemptNum int, resp *http.Response) time.Duration { + // attemptNum always starts at zero but we want to start at 1 for multiplication + attemptNum++ + + if max <= min { + // Unclear what to do here, or they are the same, so return min * + // attemptNum + return min * time.Duration(attemptNum) + } + + // Seed rand; doing this every time is fine + rand := rand.New(rand.NewSource(int64(time.Now().Nanosecond()))) + + // Pick a random number that lies somewhere between the min and max and + // multiply by the attemptNum. attemptNum starts at zero so we always + // increment here. We first get a random percentage, then apply that to the + // difference between min and max, and add to min. + jitter := rand.Float64() * float64(max-min) + jitterMin := int64(jitter) + int64(min) + return time.Duration(jitterMin * int64(attemptNum)) +} + +// PassthroughErrorHandler is an ErrorHandler that directly passes through the +// values from the net/http library for the final request. The body is not +// closed. +func PassthroughErrorHandler(resp *http.Response, err error, _ int) (*http.Response, error) { + return resp, err +} + +// Do wraps calling an HTTP method with retries. +func (c *Client) Do(req *Request) (*http.Response, error) { + if c.Logger != nil { + c.Logger.Printf("[DEBUG] %s %s", req.Method, req.URL) + } + + var resp *http.Response + var err error + + for i := 0; ; i++ { + var code int // HTTP response code + + // Always rewind the request body when non-nil. + if req.body != nil { + body, err := req.body() + if err != nil { + return resp, err + } + if c, ok := body.(io.ReadCloser); ok { + req.Request.Body = c + } else { + req.Request.Body = ioutil.NopCloser(body) + } + } + + if c.RequestLogHook != nil { + c.RequestLogHook(c.Logger, req.Request, i) + } + + // Attempt the request + resp, err = c.HTTPClient.Do(req.Request) + if resp != nil { + code = resp.StatusCode + } + + // Check if we should continue with retries. + checkOK, checkErr := c.CheckRetry(resp, err) + + if err != nil { + if c.Logger != nil { + c.Logger.Printf("[ERR] %s %s request failed: %v", req.Method, req.URL, err) + } + } else { + // Call this here to maintain the behavior of logging all requests, + // even if CheckRetry signals to stop. + if c.ResponseLogHook != nil { + // Call the response logger function if provided. + c.ResponseLogHook(c.Logger, resp) + } + } + + // Now decide if we should continue. + if !checkOK { + if checkErr != nil { + err = checkErr + } + return resp, err + } + + // We do this before drainBody beause there's no need for the I/O if + // we're breaking out + remain := c.RetryMax - i + if remain <= 0 { + break + } + + // We're going to retry, consume any response to reuse the connection. + if err == nil && resp != nil { + c.drainBody(resp.Body) + } + + wait := c.Backoff(c.RetryWaitMin, c.RetryWaitMax, i, resp) + desc := fmt.Sprintf("%s %s", req.Method, req.URL) + if code > 0 { + desc = fmt.Sprintf("%s (status: %d)", desc, code) + } + if c.Logger != nil { + c.Logger.Printf("[DEBUG] %s: retrying in %s (%d left)", desc, wait, remain) + } + time.Sleep(wait) + } + + if c.ErrorHandler != nil { + return c.ErrorHandler(resp, err, c.RetryMax+1) + } + + // By default, we close the response body and return an error without + // returning the response + if resp != nil { + resp.Body.Close() + } + return nil, fmt.Errorf("%s %s giving up after %d attempts", + req.Method, req.URL, c.RetryMax+1) +} + +// Try to read the response body so we can reuse this connection. +func (c *Client) drainBody(body io.ReadCloser) { + defer body.Close() + _, err := io.Copy(ioutil.Discard, io.LimitReader(body, respReadLimit)) + if err != nil { + if c.Logger != nil { + c.Logger.Printf("[ERR] error reading response body: %v", err) + } + } +} + +// Get is a shortcut for doing a GET request without making a new client. +func Get(url string) (*http.Response, error) { + return defaultClient.Get(url) +} + +// Get is a convenience helper for doing simple GET requests. +func (c *Client) Get(url string) (*http.Response, error) { + req, err := NewRequest("GET", url, nil) + if err != nil { + return nil, err + } + return c.Do(req) +} + +// Head is a shortcut for doing a HEAD request without making a new client. +func Head(url string) (*http.Response, error) { + return defaultClient.Head(url) +} + +// Head is a convenience method for doing simple HEAD requests. +func (c *Client) Head(url string) (*http.Response, error) { + req, err := NewRequest("HEAD", url, nil) + if err != nil { + return nil, err + } + return c.Do(req) +} + +// Post is a shortcut for doing a POST request without making a new client. +func Post(url, bodyType string, body interface{}) (*http.Response, error) { + return defaultClient.Post(url, bodyType, body) +} + +// Post is a convenience method for doing simple POST requests. +func (c *Client) Post(url, bodyType string, body interface{}) (*http.Response, error) { + req, err := NewRequest("POST", url, body) + if err != nil { + return nil, err + } + req.Header.Set("Content-Type", bodyType) + return c.Do(req) +} + +// PostForm is a shortcut to perform a POST with form data without creating +// a new client. +func PostForm(url string, data url.Values) (*http.Response, error) { + return defaultClient.PostForm(url, data) +} + +// PostForm is a convenience method for doing simple POST operations using +// pre-filled url.Values form data. +func (c *Client) PostForm(url string, data url.Values) (*http.Response, error) { + return c.Post(url, "application/x-www-form-urlencoded", strings.NewReader(data.Encode())) +} -- cgit v1.2.3