micro/util/kubernetes/client/watch.go

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package client
import (
"bufio"
"context"
"encoding/json"
"errors"
"net/http"
"github.com/unistack-org/micro/v3/util/kubernetes/api"
)
const (
// EventTypes used
Added EventType = "ADDED"
Modified EventType = "MODIFIED"
Deleted EventType = "DELETED"
Error EventType = "ERROR"
)
// Watcher is used to watch for events
type Watcher interface {
// A channel of events
Chan() <-chan Event
// Stop the watcher
Stop()
}
// EventType defines the possible types of events.
type EventType string
// Event represents a single event to a watched resource.
type Event struct {
Type EventType `json:"type"`
Object json.RawMessage `json:"object"`
}
// bodyWatcher scans the body of a request for chunks
type bodyWatcher struct {
results chan Event
cancel func()
stop chan bool
res *http.Response
req *api.Request
}
// Changes returns the results channel
func (wr *bodyWatcher) Chan() <-chan Event {
return wr.results
}
// Stop cancels the request
func (wr *bodyWatcher) Stop() {
select {
case <-wr.stop:
return
default:
// cancel the request
wr.cancel()
// stop the watcher
close(wr.stop)
}
}
func (wr *bodyWatcher) stream() {
reader := bufio.NewReader(wr.res.Body)
go func() {
for {
// read a line
b, err := reader.ReadBytes('\n')
if err != nil {
return
}
// send the event
var event Event
if err := json.Unmarshal(b, &event); err != nil {
continue
}
select {
case <-wr.stop:
return
case wr.results <- event:
}
}
}()
}
// newWatcher creates a k8s body watcher for
// a given http request
func newWatcher(req *api.Request) (Watcher, error) {
// set request context so we can cancel the request
ctx, cancel := context.WithCancel(context.Background())
req.Context(ctx)
// do the raw request
res, err := req.Raw()
if err != nil {
cancel()
return nil, err
}
if res.StatusCode < 200 || res.StatusCode >= 300 {
cancel()
// close the response body
res.Body.Close()
// return an error
return nil, errors.New(res.Request.URL.String() + ": " + res.Status)
}
wr := &bodyWatcher{
results: make(chan Event),
stop: make(chan bool),
cancel: cancel,
req: req,
res: res,
}
go wr.stream()
return wr, nil
}