145 lines
3.6 KiB
Go
145 lines
3.6 KiB
Go
package notifications
|
|
|
|
import (
|
|
"bytes"
|
|
"encoding/json"
|
|
"fmt"
|
|
"net/http"
|
|
"sync"
|
|
"time"
|
|
)
|
|
|
|
// httpSink implements a single-flight, http notification endpoint. This is
|
|
// very lightweight in that it only makes an attempt at an http request.
|
|
// Reliability should be provided by the caller.
|
|
type httpSink struct {
|
|
url string
|
|
|
|
mu sync.Mutex
|
|
closed bool
|
|
client *http.Client
|
|
listeners []httpStatusListener
|
|
|
|
// TODO(stevvooe): Allow one to configure the media type accepted by this
|
|
// sink and choose the serialization based on that.
|
|
}
|
|
|
|
// newHTTPSink returns an unreliable, single-flight http sink. Wrap in other
|
|
// sinks for increased reliability.
|
|
func newHTTPSink(u string, timeout time.Duration, headers http.Header, listeners ...httpStatusListener) *httpSink {
|
|
return &httpSink{
|
|
url: u,
|
|
listeners: listeners,
|
|
client: &http.Client{
|
|
Transport: &headerRoundTripper{
|
|
Transport: http.DefaultTransport.(*http.Transport),
|
|
headers: headers,
|
|
},
|
|
Timeout: timeout,
|
|
},
|
|
}
|
|
}
|
|
|
|
// httpStatusListener is called on various outcomes of sending notifications.
|
|
type httpStatusListener interface {
|
|
success(status int, events ...Event)
|
|
failure(status int, events ...Event)
|
|
err(err error, events ...Event)
|
|
}
|
|
|
|
// Accept makes an attempt to notify the endpoint, returning an error if it
|
|
// fails. It is the caller's responsibility to retry on error. The events are
|
|
// accepted or rejected as a group.
|
|
func (hs *httpSink) Write(events ...Event) error {
|
|
hs.mu.Lock()
|
|
defer hs.mu.Unlock()
|
|
|
|
if hs.closed {
|
|
return ErrSinkClosed
|
|
}
|
|
|
|
envelope := Envelope{
|
|
Events: events,
|
|
}
|
|
|
|
// TODO(stevvooe): It is not ideal to keep re-encoding the request body on
|
|
// retry but we are going to do it to keep the code simple. It is likely
|
|
// we could change the event struct to manage its own buffer.
|
|
|
|
p, err := json.MarshalIndent(envelope, "", " ")
|
|
if err != nil {
|
|
for _, listener := range hs.listeners {
|
|
listener.err(err, events...)
|
|
}
|
|
return fmt.Errorf("%v: error marshaling event envelope: %v", hs, err)
|
|
}
|
|
|
|
body := bytes.NewReader(p)
|
|
resp, err := hs.client.Post(hs.url, EventsMediaType, body)
|
|
if err != nil {
|
|
for _, listener := range hs.listeners {
|
|
listener.err(err, events...)
|
|
}
|
|
|
|
return fmt.Errorf("%v: error posting: %v", hs, err)
|
|
}
|
|
|
|
// The notifier will treat any 2xx or 3xx response as accepted by the
|
|
// endpoint.
|
|
switch {
|
|
case resp.StatusCode >= 200 && resp.StatusCode < 400:
|
|
for _, listener := range hs.listeners {
|
|
listener.success(resp.StatusCode, events...)
|
|
}
|
|
|
|
// TODO(stevvooe): This is a little accepting: we may want to support
|
|
// unsupported media type responses with retries using the correct
|
|
// media type. There may also be cases that will never work.
|
|
|
|
return nil
|
|
default:
|
|
for _, listener := range hs.listeners {
|
|
listener.failure(resp.StatusCode, events...)
|
|
}
|
|
return fmt.Errorf("%v: response status %v unaccepted", hs, resp.Status)
|
|
}
|
|
}
|
|
|
|
// Close the endpoint
|
|
func (hs *httpSink) Close() error {
|
|
hs.mu.Lock()
|
|
defer hs.mu.Unlock()
|
|
|
|
if hs.closed {
|
|
return fmt.Errorf("httpsink: already closed")
|
|
}
|
|
|
|
hs.closed = true
|
|
return nil
|
|
}
|
|
|
|
func (hs *httpSink) String() string {
|
|
return fmt.Sprintf("httpSink{%s}", hs.url)
|
|
}
|
|
|
|
type headerRoundTripper struct {
|
|
*http.Transport // must be transport to support CancelRequest
|
|
headers http.Header
|
|
}
|
|
|
|
func (hrt *headerRoundTripper) RoundTrip(req *http.Request) (*http.Response, error) {
|
|
var nreq http.Request
|
|
nreq = *req
|
|
nreq.Header = make(http.Header)
|
|
|
|
merge := func(headers http.Header) {
|
|
for k, v := range headers {
|
|
nreq.Header[k] = append(nreq.Header[k], v...)
|
|
}
|
|
}
|
|
|
|
merge(req.Header)
|
|
merge(hrt.headers)
|
|
|
|
return hrt.Transport.RoundTrip(&nreq)
|
|
}
|