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Amazon ElastiCache
User Guide (API Version 2015-02-02)

Event Notifications and Amazon SNS

ElastiCache can publish messages using Amazon Simple Notification Service (SNS) when significant events happen on a cache cluster. This feature can be used to refresh the server-lists on client machines connected to individual cache node endpoints of a cache cluster.

Note

For more information on Amazon Simple Notification Service (SNS), including information on pricing and links to the Amazon SNS documentation, go to the Amazon SNS product page.

Notifications are published to a specified Amazon SNS topic. The following are requirements for notifications:

  • Only one topic can be configured for ElastiCache notifications.

  • The AWS account that owns the Amazon SNS topic must be the same account that owns the cache cluster on which notifications are enabled.

Example ElastiCache SNS Notification

The following example shows an ElastiCache Amazon SNS notification for successfully creating a cache cluster.

{
    "Date": "2015-12-05T01:02:18.336Z",
    "Message": "Cache cluster created",
    "SourceIdentifier": "memcache-ni",
    "SourceType": "cache-cluster"
}

ElastiCache Events

The following ElastiCache events trigger Amazon SNS notifications:

Event Name Message Description

ElastiCache:AddCacheNodeComplete

"Finished modifying number of nodes from %d to %d"

A cache node has been added to the cache cluster and is ready for use.

ElastiCache:AddCacheNodeFailed due to insufficient free IP addresses

"Failed to modify number of nodes from %d to %d due to insufficient free IP addresses"

A cache node could not be added because there are not enough available IP addresses.

ElastiCache:CacheClusterParametersChanged

"Updated parameter %s to %s"

In case of create, also send "Updated to use a CacheParameterGroup %s"

One or more cache cluster parameters have been changed.

ElastiCache:CacheClusterProvisioningComplete

"Cache cluster created"

The provisioning of a cache cluster is completed, and the cache nodes in the cache cluster are ready to use.

ElastiCache:CacheClusterProvisioningFailed due to incompatible network state

"Failed to create the cache cluster due to incompatible network state"

An attempt was made to launch a new cache cluster into a nonexistent virtual private cloud (VPC).

ElastiCache:CacheClusterRestoreFailed

"Restore from %s failed for node %s"

ElastiCache was unable to populate the cache cluster with Redis snapshot data. This could be due to a nonexistent snapshot file in Amazon S3, or incorrect permissions on that file. If you describe the cache cluster, the status will be restore-failed. You will need to delete the cache cluster and start over.

For more information, see Seeding a New Cluster with an Externally Created Backup (Redis).

ElastiCache:CacheClusterScalingComplete

"Succeeded applying modification to cache node type to %s."

: Scale up for cache-cluster completed successfully.

ElastiCache:CacheClusterScalingFailed

"Failed applying modification to cache node type to %s."

Scale-up operation on cache-cluster failed.

ElastiCache:CacheClusterSecurityGroupModified

"Applied change to security group"

One of the following events has occurred:

  • The list of cache security groups authorized for the cache cluster has been modified.

  • One or more new EC2 security groups have been authorized on any of the cache security groups associated with the cache cluster.

  • One or more EC2 security groups have been revoked from any of the cache security groups associated with the cache cluster.

ElastiCache:CacheNodeReplaceComplete

"Finished recovery for cache nodes %s"

ElastiCache has detected that the host running a cache node is degraded or unreachable and has completed replacing the cache node.

Note

The DNS entry for the replaced cache node is not changed.

In most instances, you do not need to refresh the server-list for your clients when this event occurs. However, some cache client libraries may stop using the cache node even after ElastiCache has replaced the cache node; in this case, the application should refresh the server-list when this event occurs.

ElastiCache:CacheNodesRebooted

"Cache node %s restarted"

One or more cache nodes has been rebooted.

Message (Memcached): "Cache node %s shutdown" Then a second message: "Cache node %s restarted"

ElastiCache:CreateReplicationGroupComplete

"Replication group %s created"

The replication group was successfully created.

ElastiCache:CreateReplicationGroupFailed

"Failed to create replication group %s due to unsuccessful creation of its cache cluster(s)." and "Deleting all cache clusters belonging to this replication group."

The replication group was not created.

ElastiCache:DeleteCacheClusterComplete

"Cache cluster deleted"

The deletion of a cache cluster and all associated cache nodes has completed.

ElastiCache:FailoverComplete

"Failover to replica node %s completed"

Failover over to a replica node was successful.

ElastiCache:NodeReplacementCanceled

"The replacement for Cache Cluster ID: %s, Node ID: %s scheduled during the maintenance window from Start Time: %s, End Time: %s has been canceled"

A node in your cluster that was scheduled for replacement is no longer scheduled for replacement.

ElastiCache:NodeReplacementRescheduled

"The replacement in maintenance window for node with Cache Cluster ID: %s, Node ID: %s has re-scheduled from Previous Start Time: %s, Previous End Time: %s to New Start Time: %s, New End Time: %s""

A node in your cluster previously scheduled for replacement has been rescheduled for replacement during the new window described in the notification.

For information on what actions you can take, go to Actions You Can Take When a Node is Scheduled for Replacement.

ElastiCache:NodeReplacementScheduled

"The node with Cache Cluster ID: %s, Node ID: %s is scheduled for replacement during the maintenance window from Start Time: %s, End Time: %s"

A node in your cluster is scheduled for replacement during the window described in the notification.

For information on what actions you can take, go to Actions You Can Take When a Node is Scheduled for Replacement.

ElastiCache:RemoveCacheNodeComplete

"Removed cache nodes %s"

A cache node has been removed from the cache cluster.

ElastiCache:ReplicationGroupScalingComplete

"Succeeded applying modification to cache node type to %s."

Scale-up operation on replication group completed successfully.

ElastiCache:ReplicationGroupScalingFailed

"Failed applying modification to cache node type to %s."

Scale-up operation on replication group failed.

ElastiCache:SnapshotComplete

"Snapshot succeeded for snapshot with ID '%s' of cache cluster with ID '%s'"

A cache snapshot has completed successfully.

ElastiCache:SnapshotFailed

"Snapshot failed for snapshot with ID '%s' of cache cluster with ID '%s'"

A cache snapshot has failed. See the cluster’s cache events for more a detailed cause.

If you describe the snapshot, see DescribeSnapshots, the status will be failed.

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