/
resource_discovery.go
90 lines (76 loc) · 2.78 KB
/
resource_discovery.go
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// Copyright 2019 VMware, Inc. All Rights Reserved.
// SPDX-License-Identifier: Apache-2.0
package client
import (
"context"
"github.com/golang/protobuf/ptypes/any"
log "github.com/sirupsen/logrus"
rd "github.com/vmware/hamlet/api/resourcediscovery/v1alpha1"
"google.golang.org/genproto/googleapis/rpc/code"
"google.golang.org/genproto/googleapis/rpc/status"
)
// ResourceObserver is a generic resource observer that receives notifications
// when resources are created, updated, or deleted.
type ResourceObserver interface {
// OnCreate is called when a new resource is created.
OnCreate(*any.Any) error
// OnUpdate is called when an existing resource is updated.
OnUpdate(*any.Any) error
// OnDelete is called when an existing resource is deleted.
OnDelete(*any.Any) error
}
// notifyObserver notifies the observer about a particular event on a particular
// resource as received from the federated service mesh owner.
func (c *client) notifyObserver(observer ResourceObserver, res *rd.StreamResponse) error {
switch res.Operation {
case rd.StreamResponse_CREATE:
return observer.OnCreate(res.Resource)
case rd.StreamResponse_UPDATE:
return observer.OnUpdate(res.Resource)
case rd.StreamResponse_DELETE:
return observer.OnDelete(res.Resource)
default:
log.WithField("operation", res.Operation).Errorln("Unable to handle operation")
return nil
}
}
// prepareAcknowledgement prepares the acknowledgement for a previously consumed
// notification from the federated service mesh owner.
func (c *client) prepareAcknowledgement(req *rd.StreamRequest, nonce string, err error) {
req.ResponseNonce = nonce
if err == nil {
req.Status = &status.Status{Code: int32(code.Code_OK)}
} else {
log.WithField("err", err).Errorln("Error occurred while processing stream response")
req.Status = &status.Status{Code: int32(code.Code_UNAVAILABLE), Message: err.Error()}
}
}
func (c *client) WatchResources(ctx context.Context, resourceUrl string, observer ResourceObserver) error {
// Create a stream instance.
stream, err := c.dsClient.EstablishStream(ctx)
if err != nil {
log.WithField("err", err).Errorln("Error occurred while creating stream instance")
return err
}
// Create the initial stream request.
req := &rd.StreamRequest{ResourceUrl: resourceUrl}
// Loop until the stream has ended.
for {
// Send the stream request.
err := stream.Send(req)
if err != nil {
log.WithField("err", err).Errorln("Error occurred while sending stream request")
return err
}
// Receive a message.
res, err := stream.Recv()
if err != nil {
log.WithField("err", err).Errorln("Error occurred while consuming stream response")
return err
}
// Notify the observer.
err = c.notifyObserver(observer, res)
// Prepare the acknowledgement.
c.prepareAcknowledgement(req, res.Nonce, err)
}
}