Notice

This document is for a development version of Ceph.

Bucket Notifications

New in version Nautilus.

Changed in version Squid: A new “v2” format for Topic and Notification metadata can be enabled with the notification_v2 zone feature.

Bucket notifications provide a mechanism for sending information out of radosgw when certain events happen on the bucket. Notifications can be sent to HTTP endpoints, AMQP0.9.1 endpoints, and Kafka endpoints.

A user can create topics. A topic entity is defined by its name and is “per tenant”. A user can associate its topics (via notification configuration) only with buckets it owns.

A notification entity must be created in order to send event notifications for a specific bucket. A notification entity can be created either for a subset of event types or for all “Removed” and “Created” event types (which is the default). The notification may also filter out events based on matches of the prefixes and suffixes of (1) the keys, (2) the metadata attributes attached to the object, or (3) the object tags. Regular-expression matching can also be used on these to create filters. There can be multiple notifications for any specific topic, and the same topic can used for multiple notifications.

REST API has been defined so as to provide configuration and control interfaces for the bucket notification mechanism.

Note

To enable bucket notifications API, the rgw_enable_apis configuration parameter should contain: “notifications”.

Notification Reliability

Notifications can be sent synchronously or asynchronously. This section describes the latency and reliability that you should expect for synchronous and asynchronous notifications.

Synchronous Notifications

Notifications can be sent synchronously, as part of the operation that triggered them. In this mode, the operation is acknowledged (acked) only after the notification is sent to the topic’s configured endpoint. This means that the round trip time of the notification (the time it takes to send the notification to the topic’s endpoint plus the time it takes to receive the acknowledgement) is added to the latency of the operation itself.

Note

The original triggering operation is considered successful even if the notification fails with an error, cannot be delivered, or times out.

Asynchronous Notifications

Notifications can be sent asynchronously. They are committed into persistent storage and then asynchronously sent to the topic’s configured endpoint. In this case, the only latency added to the original operation is the latency added when the notification is committed to persistent storage.

Note

If the notification fails with an error, cannot be delivered, or times out, it is retried until it is successfully acknowledged. You can control its retry with time_to_live/max_retries to have a time/retry limit and control the retry frequency with retry_sleep_duration

Tip

To minimize the latency added by asynchronous notification, we recommended placing the “log” pool on fast media.

Topic Management via CLI

Fetch the configuration of all topics associated with tenants by running the following command:

radosgw-admin topic list [--tenant={tenant}]  [--uid={user}]

Fetch the configuration of a specific topic by running the following command:

radosgw-admin topic get --topic={topic-name} [--tenant={tenant}]

Remove a topic by running the following command:

radosgw-admin topic rm --topic={topic-name} [--tenant={tenant}]

Notification Performance Statistics

  • pubsub_event_triggered: a running counter of events that have at least one topic associated with them

  • pubsub_event_lost: a running counter of events that had topics associated with them, but that were not pushed to any of the endpoints

  • pubsub_push_ok: a running counter, for all notifications, of events successfully pushed to their endpoints

  • pubsub_push_fail: a running counter, for all notifications, of events that failed to be pushed to their endpoints

  • pubsub_push_pending: the gauge value of events pushed to an endpoint but not acked or nacked yet

Note

pubsub_event_triggered and pubsub_event_lost are incremented per event on each notification, but pubsub_push_ok and pubsub_push_fail are incremented per push action on each notification.

Bucket Notification REST API

Topics

Note

In all topic actions, the parameters are URL-encoded and sent in the message body using this content type: application/x-www-form-urlencoded.

Create a Topic

This creates a new topic. Provide the topic with push endpoint parameters, which will be used later when a notification is created. A response is generated. A successful response includes the topic’s ARN (the “Amazon Resource Name”, a unique identifier used to reference the topic). To update a topic, use the same command that you used to create it (but when updating, use the name of an existing topic and different endpoint values).

Tip

Any notification already associated with the topic must be re-created in order for the topic to update.

POST

Action=CreateTopic
&Name=<topic-name>
[&Attributes.entry.1.key=amqp-exchange&Attributes.entry.1.value=<exchange>]
[&Attributes.entry.2.key=amqp-ack-level&Attributes.entry.2.value=none|broker|routable]
[&Attributes.entry.3.key=verify-ssl&Attributes.entry.3.value=true|false]
[&Attributes.entry.4.key=kafka-ack-level&Attributes.entry.4.value=none|broker]
[&Attributes.entry.5.key=use-ssl&Attributes.entry.5.value=true|false]
[&Attributes.entry.6.key=ca-location&Attributes.entry.6.value=<file path>]
[&Attributes.entry.7.key=OpaqueData&Attributes.entry.7.value=<opaque data>]
[&Attributes.entry.8.key=push-endpoint&Attributes.entry.8.value=<endpoint>]
[&Attributes.entry.9.key=persistent&Attributes.entry.9.value=true|false]
[&Attributes.entry.10.key=cloudevents&Attributes.entry.10.value=true|false]
[&Attributes.entry.11.key=mechanism&Attributes.entry.11.value=<mechanism>]
[&Attributes.entry.12.key=time_to_live&Attributes.entry.12.value=<seconds to live>]
[&Attributes.entry.13.key=max_retries&Attributes.entry.13.value=<retries number>]
[&Attributes.entry.14.key=retry_sleep_duration&Attributes.entry.14.value=<sleep seconds>]
[&Attributes.entry.15.key=Policy&Attributes.entry.15.value=<policy-JSON-string>]
[&Attributes.entry.16.key=user-name&Attributes.entry.16.value=<user-name-string>]
[&Attributes.entry.17.key=password&Attributes.entry.17.value=<password-string>]

Request parameters:

  • push-endpoint: This is the URI of an endpoint to send push notifications to.

  • OpaqueData: Opaque data is set in the topic configuration and added to all notifications that are triggered by the topic.

  • persistent: This indicates whether notifications to this endpoint are persistent (=asynchronous) or not persistent. (This is “false” by default.)

  • time_to_live: This will limit the time (in seconds) to retain the notifications. default value is taken from rgw_topic_persistency_time_to_live. providing a value overrides the global value. zero value means infinite time to live.

  • max_retries: This will limit the max retries before expiring notifications. default value is taken from rgw_topic_persistency_max_retries. providing a value overrides the global value. zero value means infinite retries.

  • retry_sleep_duration: This will control the frequency of retrying the notifications. default value is taken from rgw_topic_persistency_sleep_duration. providing a value overrides the global value. zero value mean there is no delay between retries.

  • Policy: This will control who can access the topic in addition to the owner of the topic. The policy passed needs to be a JSON string similar to bucket policy. For example, one can send a policy string as follows:

    {
      "Version": "2012-10-17",
      "Statement": [{
        "Effect": "Allow",
        "Principal": {"AWS": ["arn:aws:iam::usfolks:user/fred:subuser"]},
        "Action": ["sns:GetTopicAttributes","sns:Publish"],
        "Resource": ["arn:aws:sns:default::mytopic"],
      }]
    }
    

    Currently, we support only the following actions: - sns:GetTopicAttributes To list or get existing topics - sns:SetTopicAttributes To set attributes for the existing topic - sns:DeleteTopic To delete the existing topic - sns:Publish To be able to create/subscribe notification on existing topic

  • HTTP endpoint

  • URI: http[s]://<fqdn>[:<port]

  • port: This defaults to 80 for HTTP and 443 for HTTPS.

  • verify-ssl: This indicates whether the server certificate is validated by the client. (This is “true” by default.)

  • cloudevents: This indicates whether the HTTP header should contain attributes according to the S3 CloudEvents Spec. (This is “false” by default.)

  • AMQP0.9.1 endpoint

  • URI: amqp[s]://[<user>:<password>@]<fqdn>[:<port>][/<vhost>]

  • user/password: This defaults to “guest/guest”.

  • user/password: This must be provided only over HTTPS. Topic creation requests will otherwise be rejected.

  • port: This defaults to 5672 for unencrypted connections and 5671 for SSL-encrypted connections.

  • vhost: This defaults to “/”.

  • verify-ssl: This indicates whether the server certificate is validated by the client. (This is “true” by default.)

  • If ca-location is provided and a secure connection is used, the specified CA will be used to authenticate the broker. The default CA will not be used.

  • amqp-exchange: The exchanges must exist and must be able to route messages based on topics. This parameter is mandatory.

  • amqp-ack-level: No end2end acking is required. Messages may persist in the broker before being delivered to their final destinations. Three ack methods exist:

  • “none”: The message is considered “delivered” if it is sent to the broker.

  • “broker”: The message is considered “delivered” if it is acked by the broker (default).

  • “routable”: The message is considered “delivered” if the broker can route to a consumer.

Tip

The topic-name (see Create a Topic) is used for the AMQP topic (“routing key” for a topic exchange).

  • Kafka endpoint

  • URI: kafka://[<user>:<password>@]<fqdn>[:<port]

  • use-ssl: If this is set to “true”, a secure connection is used to connect to the broker. (This is “false” by default.)

  • ca-location: If this is provided and a secure connection is used, the specified CA will be used instead of the default CA to authenticate the broker.

  • user/password: This should be provided over HTTPS. If not, the config parameter rgw_allow_notification_secrets_in_cleartext must be true in order to create topics.

  • user/password: This should be provided together with use-ssl. If not, the broker credentials will be sent over insecure transport.

  • mechanism: may be provided together with user/password (default: PLAIN). The supported SASL mechanisms are:

  • user-name: User name to use when connecting to the Kafka broker. If both this parameter and URI user are provided then this parameter overrides the URI user.

    The same security considerations are in place for this parameter as are for user/password.

  • password: Password to use when connecting to the Kafka broker. If both this parameter and URI password are provided then this parameter overrides the URI password.

    The same security considerations are in place for this parameter as are for user/password.

  • PLAIN

  • SCRAM-SHA-256

  • SCRAM-SHA-512

  • GSSAPI

  • OAUTHBEARER

  • port: This defaults to 9092.

  • kafka-ack-level: No end2end acking is required. Messages may persist in the broker before being delivered to their final destinations. Two ack methods exist:

  • “none”: Messages are considered “delivered” if sent to the broker.

  • “broker”: Messages are considered “delivered” if acked by the broker. (This is the default.)

Note

  • The key-value pair of a specific parameter need not reside in the same line as the parameter, and need not appear in any specific order, but it must use the same index.

  • Attribute indexing need not be sequential and need not start from any specific value.

  • AWS Create Topic provides a detailed explanation of the endpoint attributes format. In our case, however, different keys and values are used.

The response has the following format:

<CreateTopicResponse xmlns="https://sns.amazonaws.com/doc/2010-03-31/">
    <CreateTopicResult>
        <TopicArn></TopicArn>
    </CreateTopicResult>
    <ResponseMetadata>
        <RequestId></RequestId>
    </ResponseMetadata>
</CreateTopicResponse>

The topic ARN in the response has the following format:

arn:aws:sns:<zone-group>:<tenant>:<topic>

Get Topic Attributes

This returns information about a specific topic. This includes push-endpoint information, if provided.

POST

Action=GetTopicAttributes
&TopicArn=<topic-arn>

The response has the following format:

<GetTopicAttributesResponse>
    <GetTopicAttributesResult>
        <Attributes>
            <entry>
                <key>User</key>
                <value></value>
            </entry>
            <entry>
                <key>Name</key>
                <value></value>
            </entry>
            <entry>
                <key>EndPoint</key>
                <value></value>
            </entry>
            <entry>
                <key>TopicArn</key>
                <value></value>
            </entry>
            <entry>
                <key>OpaqueData</key>
                <value></value>
            </entry>
        </Attributes>
    </GetTopicAttributesResult>
    <ResponseMetadata>
        <RequestId></RequestId>
    </ResponseMetadata>
</GetTopicAttributesResponse>
  • User: the name of the user that created the topic.

  • Name: the name of the topic.

  • EndPoint: The JSON-formatted endpoint parameters, including:
    • EndpointAddress: The push-endpoint URL.

    • EndpointArgs: The push-endpoint args.

    • EndpointTopic: The topic name to be sent to the endpoint (can be different than the above topic name).

    • HasStoredSecret: This is “true” if the endpoint URL contains user/password information. In this case, the request must be made over HTTPS. The “topic get” request will otherwise be rejected.

    • Persistent: This is “true” if the topic is persistent.

    • TimeToLive: This will limit the time (in seconds) to retain the notifications.

    • MaxRetries: This will limit the max retries before expiring notifications.

    • RetrySleepDuration: This will control the frequency of retrying the notifications.

  • TopicArn: topic ARN.

  • OpaqueData: The opaque data set on the topic.

  • Policy: Any access permission set on the topic.

Get Topic Information

This returns information about a specific topic. This includes push-endpoint information, if provided. Note that this API is now deprecated in favor of the AWS compliant GetTopicAttributes API.

POST

Action=GetTopic
&TopicArn=<topic-arn>

The response has the following format:

<GetTopicResponse>
    <GetTopicResult>
        <Topic>
            <User></User>
            <Name></Name>
            <EndPoint>
                <EndpointAddress></EndpointAddress>
                <EndpointArgs></EndpointArgs>
                <EndpointTopic></EndpointTopic>
                <HasStoredSecret></HasStoredSecret>
                <Persistent></Persistent>
            </EndPoint>
            <TopicArn></TopicArn>
            <OpaqueData></OpaqueData>
        </Topic>
    </GetTopicResult>
    <ResponseMetadata>
        <RequestId></RequestId>
    </ResponseMetadata>
</GetTopicResponse>
  • User: The name of the user that created the topic.

  • Name: The name of the topic.

  • EndpointAddress: The push-endpoint URL.

  • EndpointArgs: The push-endpoint args.

  • EndpointTopic: The topic name to be sent to the endpoint (which can be different than the above topic name).

  • HasStoredSecret: This is “true” if the endpoint URL contains user/password information. In this case, the request must be made over HTTPS. The “topic get” request will otherwise be rejected.

  • Persistent: “true” if topic is persistent.

  • TopicArn: topic ARN.

  • OpaqueData: the opaque data set on the topic.

  • Policy: Any access permission set on the topic.

Delete Topic

POST

Action=DeleteTopic
&TopicArn=<topic-arn>

This deletes the specified topic.

Note

  • Deleting an unknown notification (for example, double delete) is not considered an error.

  • Deleting a topic does not automatically delete all notifications associated with it.

The response has the following format:

<DeleteTopicResponse xmlns="https://sns.amazonaws.com/doc/2010-03-31/">
    <ResponseMetadata>
        <RequestId></RequestId>
    </ResponseMetadata>
</DeleteTopicResponse>

List Topics

List all topics associated with a tenant.

POST

Action=ListTopics

The response has the following format:

<ListTopicsResponse xmlns="https://sns.amazonaws.com/doc/2010-03-31/">
    <ListTopicsResult>
        <Topics>
            <member>
                <User></User>
                <Name></Name>
                <EndPoint>
                    <EndpointAddress></EndpointAddress>
                    <EndpointArgs></EndpointArgs>
                    <EndpointTopic></EndpointTopic>
                </EndPoint>
                <TopicArn></TopicArn>
                <OpaqueData></OpaqueData>
            </member>
        </Topics>
    </ListTopicsResult>
    <ResponseMetadata>
        <RequestId></RequestId>
    </ResponseMetadata>
</ListTopicsResponse>
  • If the endpoint URL contains user/password information in any part of the topic, the request must be made over HTTPS. The “topic list” request will otherwise be rejected.

Set Topic Attributes

POST

Action=SetTopicAttributes
&TopicArn=<topic-arn>&AttributeName=<attribute-name>&AttributeValue=<attribute-value>

This allows to set/modify existing attributes on the specified topic.

Note

  • The AttributeName passed will either be updated or created (if not exist) with AttributeValue passed.

  • Any unsupported AttributeName passed will result in error 400.

The response has the following format:

<SetTopicAttributesResponse xmlns="https://sns.amazonaws.com/doc/2010-03-31/">
    <ResponseMetadata>
        <RequestId></RequestId>
    </ResponseMetadata>
</SetTopicAttributesResponse>

Valid AttributeName that can be passed:

  • push-endpoint: This is the URI of an endpoint to send push notifications to.

  • OpaqueData: Opaque data is set in the topic configuration and added to all notifications that are triggered by the topic.

  • persistent: This indicates whether notifications to this endpoint are persistent (=asynchronous) or not persistent. (This is “false” by default.)

  • time_to_live: This will limit the time (in seconds) to retain the notifications.

  • max_retries: This will limit the max retries before expiring notifications.

  • retry_sleep_duration: This will control the frequency of retrying the notifications.

  • Policy: This will control who can access the topic other than owner of the topic.

  • verify-ssl: This indicates whether the server certificates must be validated by the client. This is “true” by default.

  • use-ssl: If this is set to “true”, a secure connection is used to connect to the broker. This is “false” by default.

  • cloudevents: This indicates whether the HTTP header should contain attributes according to the S3 CloudEvents Spec.

  • amqp-exchange: The exchanges must exist and must be able to route messages based on topics.

  • amqp-ack-level: No end2end acknowledgement is required. Messages may persist in the broker before being delivered to their final destinations.

  • ca-location: If this is provided and a secure connection is used, the specified CA will be used instead of the default CA to authenticate the broker.

  • mechanism: may be provided together with user/password (default: PLAIN).

  • kafka-ack-level: No end2end acknowledgement is required. Messages may persist in the broker before being delivered to their final destinations.

Notifications

Detailed under: Bucket Operations.

Note

  • “Abort Multipart Upload” request does not emit a notification

  • Both “Initiate Multipart Upload” and “POST Object” requests will emit an s3:ObjectCreated:Post notification

Events

Events are in JSON format (regardless of the actual endpoint), and are S3-compatible. For example:

{"Records":[
    {
        "eventVersion":"2.1",
        "eventSource":"ceph:s3",
        "awsRegion":"zonegroup1",
        "eventTime":"2019-11-22T13:47:35.124724Z",
        "eventName":"ObjectCreated:Put",
        "userIdentity":{
            "principalId":"tester"
        },
        "requestParameters":{
            "sourceIPAddress":""
        },
        "responseElements":{
            "x-amz-request-id":"503a4c37-85eb-47cd-8681-2817e80b4281.5330.903595",
            "x-amz-id-2":"14d2-zone1-zonegroup1"
        },
        "s3":{
            "s3SchemaVersion":"1.0",
            "configurationId":"mynotif1",
            "bucket":{
                "name":"mybucket1",
                "ownerIdentity":{
                    "principalId":"tester"
                },
                "arn":"arn:aws:s3:zonegroup1::mybucket1",
                "id":"503a4c37-85eb-47cd-8681-2817e80b4281.5332.38"
            },
            "object":{
                "key":"myimage1.jpg",
                "size":"1024",
                "eTag":"37b51d194a7513e45b56f6524f2d51f2",
                "versionId":"",
                "sequencer": "F7E6D75DC742D108",
                "metadata":[],
                "tags":[]
            }
        },
        "eventId":"",
        "opaqueData":"me@example.com"
    }
]}
  • awsRegion: The zonegroup.

  • eventTime: The timestamp, indicating when the event was triggered.

  • eventName: For the list of supported events see: S3 Notification Compatibility. Note that eventName values do not start with the s3: prefix.

  • userIdentity.principalId: The user that triggered the change.

  • requestParameters.sourceIPAddress: not supported

  • responseElements.x-amz-request-id: The request ID of the original change.

  • responseElements.x_amz_id_2: The RGW on which the change was made.

  • s3.configurationId: The notification ID that created the event.

  • s3.bucket.name: The name of the bucket.

  • s3.bucket.ownerIdentity.principalId: The owner of the bucket.

  • s3.bucket.arn: The ARN of the bucket.

  • s3.bucket.id: The ID of the bucket. (This is an extension to the S3 notification API.)

  • s3.object.key: The object key.

  • s3.object.size: The object size.

  • s3.object.eTag: The object etag.

  • s3.object.versionId: The object version, if the bucket is versioned. When a copy is made, it includes the version of the target object. When a delete marker is created, it includes the version of the delete marker.

  • s3.object.sequencer: The monotonically-increasing identifier of the “change per object” (hexadecimal format).

  • s3.object.metadata: Any metadata set on the object that is sent as x-amz-meta- (that is, any metadata set on the object that is sent as an extension to the S3 notification API).

  • s3.object.tags: Any tags set on the object. (This is an extension to the S3 notification API.)

  • s3.eventId: The unique ID of the event, which could be used for acking. (This is an extension to the S3 notification API.)

  • s3.opaqueData: This means that “opaque data” is set in the topic configuration and is added to all notifications triggered by the topic. (This is an extension to the S3 notification API.)

Brought to you by the Ceph Foundation

The Ceph Documentation is a community resource funded and hosted by the non-profit Ceph Foundation. If you would like to support this and our other efforts, please consider joining now.