traefik/vendor/github.com/vdemeester/docker-events/events.go

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2017-02-07 21:33:23 +00:00
package events
import (
"encoding/json"
"io"
"golang.org/x/net/context"
"github.com/docker/engine-api/client"
"github.com/docker/engine-api/types"
eventtypes "github.com/docker/engine-api/types/events"
)
// Monitor subscribes to the docker events api using engine api and will execute the
// specified function on each message.
// It will pass the specified options to the underline method (i.e Events).
func Monitor(ctx context.Context, cli client.SystemAPIClient, options types.EventsOptions, fun func(m eventtypes.Message)) chan error {
handler := NewHandler(func(_ eventtypes.Message) string {
// Let's return always the same thing to not filter at all
return ""
})
handler.Handle("", fun)
return MonitorWithHandler(ctx, cli, options, handler)
}
// MonitorWithHandler subscribes to the docker events api using engine api and will pass the message
// to the specified Handler, that will take care of it.
// It will pass the specified options to the underline method (i.e Events).
func MonitorWithHandler(ctx context.Context, cli client.SystemAPIClient, options types.EventsOptions, handler *Handler) chan error {
eventChan := make(chan eventtypes.Message)
errChan := make(chan error)
started := make(chan struct{})
go handler.Watch(eventChan)
go monitorEvents(ctx, cli, options, started, eventChan, errChan)
go func() {
for {
select {
case <-ctx.Done():
// close(eventChan)
errChan <- nil
}
}
}()
<-started
return errChan
}
func monitorEvents(ctx context.Context, cli client.SystemAPIClient, options types.EventsOptions, started chan struct{}, eventChan chan eventtypes.Message, errChan chan error) {
body, err := cli.Events(ctx, options)
// Whether we successfully subscribed to events or not, we can now
// unblock the main goroutine.
close(started)
if err != nil {
errChan <- err
return
}
defer body.Close()
if err := decodeEvents(body, func(event eventtypes.Message, err error) error {
if err != nil {
return err
}
eventChan <- event
return nil
}); err != nil {
errChan <- err
return
}
}
type eventProcessor func(event eventtypes.Message, err error) error
func decodeEvents(input io.Reader, ep eventProcessor) error {
dec := json.NewDecoder(input)
for {
var event eventtypes.Message
err := dec.Decode(&event)
if err != nil && err == io.EOF {
break
}
if procErr := ep(event, err); procErr != nil {
return procErr
}
}
return nil
}