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