What on Earth is a Flocker? It's a piece of open source software that lets you run databases, key-value stores and queues inside Docker containers, and comes from ClusterHQ.
Docker is an open-source Linux container technology that runs multiple apps under a single OS inside a containing structure instead of each application having its own virtual machine with is own OS, meaning multiple OS copies.
Google is said to instantiate up to two billion containers each and every week. We might fancifully call containerisation a way of thin-provisioning operating systems to applications in a virtualised server. Snarky old IT folks might sarcastically recall multi-tasking under one OS and sniff in sorrow. Whatever.
ClusterHQ calls itself a container data management company, moving containers between physical servers, running multiple containers on a server and setting up apps as connected containers.
Flocker moves a database from one node to another and re-routes network connections. Click to enlarge the diagram.
Flocker version 0.1 enables developers to define an app as a set of connected Docker containers, deploy and then migrate them between hosts, within and between data centres. It gives them the:
- ability to define an entire application, including its databases, as a set of connected containers,
- easy migration of databases, queues and key values stores along with rest of the application and
- support for deployment to and between any public, private or bare metal clouds.
ClusterHQ, headquartered in Bristol, UK, gets a supporting quote from Gabriel Monroy, founder and CTO of Deis, who opines: “Containerised databases are not suitable for production workloads without solutions for data migration, cloning and failover."
Luke Marsden, ClusterHQ's CEO, claims: "ClusterHQ will do for containers what vCenter did for VMs. Containers and PaaS currently only capture the easy, data-free parts of an application. Flocker captures the entire app, enabling distributed data management, dynamic resource scheduling and high availability."
The Flocker founders say the primary unit of deployment for Platform-as-a-Service (PaaS) are Linux containers, and the PaaS market is growing at a 32 per cent CAGR between 2013 and 2018.
Flocker is available today on Github under an Apache 2.0 licence. Get online documentation here. ®