`principalId` i.e user identity is kept as AccessKey in
accordance with S3 spec.
Additionally responseElements{} are added starting with
`x-amz-request-id` is a hexadecimal of the event time itself in nanosecs.
`x-minio-origin-server` - points to the server generating the event.
Fixes#3556
* Implements a Peer RPC router that sends info to all Minio servers in the cluster.
* Bucket notifications are propagated to all nodes via this RPC router.
* Bucket listener configuration is persisted to separate object layer
file (`listener.json`) and peer RPCs are used to communicate changes
throughout the cluster.
* When events are generated, RPC calls to send them to other servers
where bucket listeners may be connected is implemented.
* Some bucket notification tests are now disabled as they cannot work in
the new design.
* Minor fix in `funcFromPC` to use `path.Join`
This API is precursor before implementing `minio lambda` and `mc` continous replication.
This new api is an extention to BucketNofication APIs.
// Request
```
GET /bucket?notificationARN=arn:minio:lambda:us-east-1:10:minio HTTP/1.1
...
...
```
// Response
```
{"Records": ...}
...
...
...
{"Records": ...}
```
While the existing code worked, it went to an entire cycle
of constructing event structure and end up not sending it.
Avoid this in the first place, but returning quickly if
notifications are not set on the bucket.
* Implement basic S3 notifications through queues
Supports multiple queues and three basic queue types:
1. NilQueue -- messages don't get sent anywhere
2. LogQueue -- messages get logged
3. AmqpQueue -- messages are sent to an AMQP queue
* api: Implement bucket notification.
Supports two different queue types
- AMQP
- ElasticSearch.
* Add support for redis
Harshavardhana