| title: | Layer |
|---|---|
| description: | Deis layers are homogeneous groups of nodes that perform work on behalf of a formation. Details on runtime layers, proxy layers and custom layers. |
| keywords: | layer, nodes, deis |
Layers are homogeneous groups of :ref:`Nodes <node>` that perform work on behalf of a formation. Each node in a layer has the same :ref:`Flavor` and configuration, allowing them to be scaled easily.
Runtime layers host :ref:`Containers <container>` for a formation. Nodes in a runtime layer use a Chef Databag to deploy containers for each :ref:`application` in the formation.
Proxy layers expose :ref:`Applications <application>` to the outside world. Nodes in a proxy layer use a Chef Databag to configure routing of inbound requests to :ref:`Containers <container>` hosted on runtime layers.
A layer can be serve as both a proxy and a runtime. By default, most formations are created with an initial "runtime" layer that is dual proxy/runtime, allowing an entire formation to live on one :ref:`node`.
It is also possible to create custom layers that don't provide runtime or proxy services to the formation. This is useful for scaling and managing backing services built with Chef that need to be managed alongside a formation.