Polly implements a centralized storage scheduling service that integrates with popular container schedulers of different application platforms for containerized workloads. It is an open source framework that supports use of external storage, with scheduled containerized workloads, at scale. It can be used to centralize the control of creating, mapping, snapshotting and deleting persistent data volumes on a multitude of storage platforms.

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• Configure services to interface with schedulers and groups of container runtimes
• Restrict existing volumes and new volumes to services
• Centralized control and distribution of storage resources
• Offer based mechanism for advertising storage to container schedulers
• Framework supporting direct integration to any container scheduler, storage orchestrator, and storage platform
• Basic Volume Management capabilities

Container runtime schedulers need to be integrated with every aspect of available hardware resources, including persistent storage. When requesting resources for an application the scheduler gets offers for CPU, RAM and disk.

To be able to offer persistent storage in a scalable way, the application and container scheduler needs awareness of the available resources from the underlying storage infrastructure.

The following is an intended workflow for Polly. Today the requests for volumes come through the container runtimes or libStorage compatible clients directly.

1. An application requires highly available storage with a specific set of policies applied.
2. The scheduler receives a request to start the application.
3. The scheduler checks with Polly or already is aware of outstanding offers for storage resources.
4. Scheduler send request to container runtimes to start the container with persistent storage.
5. Container runtime requests volume access from Polly.
6. Container runtime orchestrates process of starting container and attaching persistent storage with help from a libStorage storage orchestrator.

Polly provides an open framework to enable integration to any container, cloud, or storage platform.

Container runtime schedulers:

• Docker Swarm
• Mesos
• Kubernetes
• Cloud Foundry

Supported cloud and storage platforms directly comes from the libStorage project. REX-Ray is a compatible libStoage client instance that can be ran alongside the container runtimes and remotely talk with Polly.

Cloud platforms:

• AWS EC2 (EBS)
• Google Compute Engine
• OpenStack
• Private Cloud
• Public Cloud (RackSpace, and others)

Planned supported storage platforms:

• EMC ScaleIO
• XtremIO
• VMAX
• Isilon
• Others
• VirtualBox

The following command will install Polly. If using CentOS, RedHat, Ubuntu, or Debian the necessary service manager is used to bootstrap the process on startup.

curl -sSL https://dl.bintray.com/emccode/polly/install | sh -s stable

You can also install the latest staged release with the following command.

curl -sSL https://dl.bintray.com/emccode/polly/install | sh -s staged

Make sure to create an /etc/polly/config.yml following this to configure Polly properly.

Polly makes use of the open source storage plugin framework libStorage to enable storage orchestrator tools and container runtimes to make requests of storage. Any storage platform that has a driver implementation for the libStorage framework will work with Polly.