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@peterbourgon @geoffberger @travissalascox @basvanbeek @Ayiga @xescugc @willfaught @simonjefford @rossmcf @rolaveric @gaplyk @drscre
210 lines (181 sloc) 5.9 KB
package http
import (
"bytes"
"context"
"encoding/json"
"encoding/xml"
"io"
"io/ioutil"
"net/http"
"net/url"
"github.com/go-kit/kit/endpoint"
)
// HTTPClient is an interface that models *http.Client.
type HTTPClient interface {
Do(req *http.Request) (*http.Response, error)
}
// Client wraps a URL and provides a method that implements endpoint.Endpoint.
type Client struct {
client HTTPClient
method string
tgt *url.URL
enc EncodeRequestFunc
dec DecodeResponseFunc
before []RequestFunc
after []ClientResponseFunc
finalizer []ClientFinalizerFunc
bufferedStream bool
}
// NewClient constructs a usable Client for a single remote method.
func NewClient(
method string,
tgt *url.URL,
enc EncodeRequestFunc,
dec DecodeResponseFunc,
options ...ClientOption,
) *Client {
c := &Client{
client: http.DefaultClient,
method: method,
tgt: tgt,
enc: enc,
dec: dec,
before: []RequestFunc{},
after: []ClientResponseFunc{},
bufferedStream: false,
}
for _, option := range options {
option(c)
}
return c
}
// ClientOption sets an optional parameter for clients.
type ClientOption func(*Client)
// SetClient sets the underlying HTTP client used for requests.
// By default, http.DefaultClient is used.
func SetClient(client HTTPClient) ClientOption {
return func(c *Client) { c.client = client }
}
// ClientBefore sets the RequestFuncs that are applied to the outgoing HTTP
// request before it's invoked.
func ClientBefore(before ...RequestFunc) ClientOption {
return func(c *Client) { c.before = append(c.before, before...) }
}
// ClientAfter sets the ClientResponseFuncs applied to the incoming HTTP
// request prior to it being decoded. This is useful for obtaining anything off
// of the response and adding onto the context prior to decoding.
func ClientAfter(after ...ClientResponseFunc) ClientOption {
return func(c *Client) { c.after = append(c.after, after...) }
}
// ClientFinalizer is executed at the end of every HTTP request.
// By default, no finalizer is registered.
func ClientFinalizer(f ...ClientFinalizerFunc) ClientOption {
return func(s *Client) { s.finalizer = append(s.finalizer, f...) }
}
// BufferedStream sets whether the Response.Body is left open, allowing it
// to be read from later. Useful for transporting a file as a buffered stream.
// That body has to be Closed to propery end the request.
func BufferedStream(buffered bool) ClientOption {
return func(c *Client) { c.bufferedStream = buffered }
}
// Endpoint returns a usable endpoint that invokes the remote endpoint.
func (c Client) Endpoint() endpoint.Endpoint {
return func(ctx context.Context, request interface{}) (interface{}, error) {
ctx, cancel := context.WithCancel(ctx)
var (
resp *http.Response
err error
)
if c.finalizer != nil {
defer func() {
if resp != nil {
ctx = context.WithValue(ctx, ContextKeyResponseHeaders, resp.Header)
ctx = context.WithValue(ctx, ContextKeyResponseSize, resp.ContentLength)
}
for _, f := range c.finalizer {
f(ctx, err)
}
}()
}
req, err := http.NewRequest(c.method, c.tgt.String(), nil)
if err != nil {
cancel()
return nil, err
}
if err = c.enc(ctx, req, request); err != nil {
cancel()
return nil, err
}
for _, f := range c.before {
ctx = f(ctx, req)
}
resp, err = c.client.Do(req.WithContext(ctx))
if err != nil {
cancel()
return nil, err
}
// If we expect a buffered stream, we don't cancel the context when the endpoint returns.
// Instead, we should call the cancel func when closing the response body.
if c.bufferedStream {
resp.Body = bodyWithCancel{ReadCloser: resp.Body, cancel: cancel}
} else {
defer resp.Body.Close()
defer cancel()
}
for _, f := range c.after {
ctx = f(ctx, resp)
}
response, err := c.dec(ctx, resp)
if err != nil {
return nil, err
}
return response, nil
}
}
// bodyWithCancel is a wrapper for an io.ReadCloser with also a
// cancel function which is called when the Close is used
type bodyWithCancel struct {
io.ReadCloser
cancel context.CancelFunc
}
func (bwc bodyWithCancel) Close() error {
bwc.ReadCloser.Close()
bwc.cancel()
return nil
}
// ClientFinalizerFunc can be used to perform work at the end of a client HTTP
// request, after the response is returned. The principal
// intended use is for error logging. Additional response parameters are
// provided in the context under keys with the ContextKeyResponse prefix.
// Note: err may be nil. There maybe also no additional response parameters
// depending on when an error occurs.
type ClientFinalizerFunc func(ctx context.Context, err error)
// EncodeJSONRequest is an EncodeRequestFunc that serializes the request as a
// JSON object to the Request body. Many JSON-over-HTTP services can use it as
// a sensible default. If the request implements Headerer, the provided headers
// will be applied to the request.
func EncodeJSONRequest(c context.Context, r *http.Request, request interface{}) error {
r.Header.Set("Content-Type", "application/json; charset=utf-8")
if headerer, ok := request.(Headerer); ok {
for k := range headerer.Headers() {
r.Header.Set(k, headerer.Headers().Get(k))
}
}
var b bytes.Buffer
r.Body = ioutil.NopCloser(&b)
return json.NewEncoder(&b).Encode(request)
}
// EncodeXMLRequest is an EncodeRequestFunc that serializes the request as a
// XML object to the Request body. If the request implements Headerer,
// the provided headers will be applied to the request.
func EncodeXMLRequest(c context.Context, r *http.Request, request interface{}) error {
r.Header.Set("Content-Type", "text/xml; charset=utf-8")
if headerer, ok := request.(Headerer); ok {
for k := range headerer.Headers() {
r.Header.Set(k, headerer.Headers().Get(k))
}
}
var b bytes.Buffer
r.Body = ioutil.NopCloser(&b)
return xml.NewEncoder(&b).Encode(request)
}
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