Creating a cloud compute service
Overview
A cloud service is an abstraction of a compute service that corresponds to a cloud platform that provides access to virtualized compute resources, i.e., virtual machines (VMs). The cloud service provides all necessary functions to manage VMs (create, suspend/resume, shutdown). Jobs are never submitted directly to a cloud service. Instead, a VM instance behaves as a bare-metal service, to which jobs can be submitted.
The main difference between a cloud service and a virtualized cluster service is that the latter does expose the underlying physical infrastructure (e.g., it is possible to instantiate a VM on a particular physical host, or to migrate a VM between two particular physical hosts).
Creating a cloud compute service
In WRENCH, a cloud service is defined by the
wrench::CloudComputeService
class. An instantiation of a cloud
service requires the following parameters:
The name of a host on which to start the service;
A list (
std::vector
) of hostnames (all cores and all RAM of each host are available to the cloud service);A mount point (corresponding to a disk attached to the host) for the scratch space, i.e., storage local to the cloud service (used to store workflow files, as needed, during job executions); and
Maps (
std::map
) of configurable properties (wrench::CloudComputeServiceProperty
) and configurable message payloads (wrench::CloudComputeServiceMessagePayload
).
The example below creates an instance of a cloud service that runs on
host cloud_gateway
, provides access to 4 execution hosts, and has a
scratch space on the disk mounted at path /scratch
at host
cloud_gateway
. Furthermore, the VM boot time is configured to be 10
second, and the message with which the service answers resource request
description requests is configured to be 1KiB:
auto cloud_cs = simulation->add(
new wrench::CloudComputeService("cloud_gateway", {"host1", "host2", "host3", "host4"}, "/scratch/",
{{wrench::CloudComputeServiceProperty::VM_BOOT_OVERHEAD, "10s"}},
{{wrench::BareMetalComputeServiceMessagePayload::RESOURCE_DESCRIPTION_ANSWER_MESSAGE_PAYLOAD, 1024}}));
See the documentation of wrench::CloudComputeServiceProperty
and
wrench::CloudComputeServiceMessagePayload
for all possible
configuration options.
Also see the simulators in the examples/workflow_api/basic-examples/cloud-*/
and
examples/action_api/cloud-*/
directories, which use cloud compute services.