Module: Aws::EC2::Waiters

Defined in:

gems/aws-sdk-ec2/lib/aws-sdk-ec2/waiters.rb

Overview

Waiters are utility methods that poll for a particular state to occur on a client. Waiters can fail after a number of attempts at a polling interval defined for the service client.

For a list of operations that can be waited for and the client methods called for each operation, see the table below or the Client#wait_until field documentation for the Client.

Invoking a Waiter

To invoke a waiter, call #wait_until on a Client. The first parameter is the waiter name, which is specific to the service client and indicates which operation is being waited for. The second parameter is a hash of parameters that are passed to the client method called by the waiter, which varies according to the waiter name.

Wait Failures

To catch errors in a waiter, use WaiterFailed, as shown in the following example.

rescue rescue Aws::Waiters::Errors::WaiterFailed => error
  puts "failed waiting for instance running: #{error.message}
end

Configuring a Waiter

Each waiter has a default polling interval and a maximum number of attempts it will make before returning control to your program. To set these values, use the max_attempts and delay parameters in your #wait_until call. The following example waits for up to 25 seconds, polling every five seconds.

client.wait_until(...) do |w|
  w.max_attempts = 5
  w.delay = 5
end

To disable wait failures, set the value of either of these parameters to nil.

Extending a Waiter

To modify the behavior of waiters, you can register callbacks that are triggered before each polling attempt and before waiting.

The following example implements an exponential backoff in a waiter by doubling the amount of time to wait on every attempt.

client.wait_until(...) do |w|
  w.interval = 0 # disable normal sleep
  w.before_wait do |n, resp|
    sleep(n ** 2)
  end
end

Available Waiters

The following table lists the valid waiter names, the operations they call, and the default :delay and :max_attempts values.

waiter_name	params	:delay	:max_attempts
bundle_task_complete	Client#describe_bundle_tasks	15	40
conversion_task_cancelled	Client#describe_conversion_tasks	15	40
conversion_task_completed	Client#describe_conversion_tasks	15	40
conversion_task_deleted	Client#describe_conversion_tasks	15	40
customer_gateway_available	Client#describe_customer_gateways	15	40
export_task_cancelled	Client#describe_export_tasks	15	40
export_task_completed	Client#describe_export_tasks	15	40
image_available	Client#describe_images	15	40
image_exists	Client#describe_images	15	40
instance_exists	Client#describe_instances	5	40
instance_running	Client#describe_instances	15	40
instance_status_ok	Client#describe_instance_status	15	40
instance_stopped	Client#describe_instances	15	40
instance_terminated	Client#describe_instances	15	40
internet_gateway_exists	Client#describe_internet_gateways	5	6
key_pair_exists	Client#describe_key_pairs	5	6
nat_gateway_available	Client#describe_nat_gateways	15	40
nat_gateway_deleted	Client#describe_nat_gateways	15	40
network_interface_available	Client#describe_network_interfaces	20	10
password_data_available	Client#get_password_data	15	40
security_group_exists	Client#describe_security_groups	5	6
snapshot_completed	Client#describe_snapshots	15	40
snapshot_imported	Client#describe_import_snapshot_tasks	15	40
spot_instance_request_fulfilled	Client#describe_spot_instance_requests	15	40
store_image_task_complete	Client#describe_store_image_tasks	5	40
subnet_available	Client#describe_subnets	15	40
system_status_ok	Client#describe_instance_status	15	40
volume_available	Client#describe_volumes	15	40
volume_deleted	Client#describe_volumes	15	40
volume_in_use	Client#describe_volumes	15	40
vpc_available	Client#describe_vpcs	15	40
vpc_exists	Client#describe_vpcs	1	5
vpc_peering_connection_deleted	Client#describe_vpc_peering_connections	15	40
vpc_peering_connection_exists	Client#describe_vpc_peering_connections	15	40
vpn_connection_available	Client#describe_vpn_connections	15	40
vpn_connection_deleted	Client#describe_vpn_connections	15	40

Defined Under Namespace

Classes: BundleTaskComplete, ConversionTaskCancelled, ConversionTaskCompleted, ConversionTaskDeleted, CustomerGatewayAvailable, ExportTaskCancelled, ExportTaskCompleted, ImageAvailable, ImageExists, InstanceExists, InstanceRunning, InstanceStatusOk, InstanceStopped, InstanceTerminated, InternetGatewayExists, KeyPairExists, NatGatewayAvailable, NatGatewayDeleted, NetworkInterfaceAvailable, PasswordDataAvailable, SecurityGroupExists, SnapshotCompleted, SnapshotImported, SpotInstanceRequestFulfilled, StoreImageTaskComplete, SubnetAvailable, SystemStatusOk, VolumeAvailable, VolumeDeleted, VolumeInUse, VpcAvailable, VpcExists, VpcPeeringConnectionDeleted, VpcPeeringConnectionExists, VpnConnectionAvailable, VpnConnectionDeleted