On the heels of CoreOS raising a Series B, Rancher Labs has done the same, announcing the close of its own $20 million Series B today.

You could argue that all this really proves is that venture capitalists have picked containers as the next shiny object they all want to chase. But it does seem the container ecosystem is ready for the next wave of startups to push to a new level of maturity, fleshing out an ecosystem that Docker Inc. helped start.

Rancher's Series B was led by GRC SinoGreen. Prior investors Mayfield and Nexus Venture Partners participated as well.

Rancher recently released its open source container management platform, which is geared toward running containers in production. That's been an ongoing theme with containers. Developers have been using the technology in test networks, and companies throughout the ecosystem are now fortifying containers and management systems for production as well.

Competition in this area could include ContainerX, the Tectonic platform from CoreOS, and DC/OS from Mesosphere.