NetworkService controller

This is a Multus aware service controller, allowing the creation of headless services on Multus additional networks.

This was a temporary home for this code, and the master copy has moved to https://github.com/k8snetworkplumbingwg/net-service-controller. This repo will likely be removed in future.

Build

You do not need to build the project unless you want to change the code.

This project uses the operator-sdk, which you must have installed locally. Build instructions are contained here.

Installation

Install as follows (after building and pushing if you have changed the code).

kubectl apply -f manifest/install

Usage

Sample NetService objects are contained in the manifests directory, together with a sample multi-network deployment (manifests/multi.yaml). These assume networks named core and access have been created and multus is installed in the cluster.

. Each such object has the following fields.

• The name of the NetService object is the name of the resulting service that will be created.

• The netAttachDef field is the name of the network attachment definition to select on.

• The selector is the selector, with the same format as a normal service selector.

Upon creating your NetService object, a service with the same name will be created, pulling the IPs from the corresponding network, and will be kept updated as changes are made to pods.

Design

Suppose the NetService object is called example. The operator creates three things as dependencies of the NetService object.

• It creates a headless service called example-template with a selector as specified. This automatically leads the endpoints controller to create and populate an endpoints object, example-template.

• It creates a headless service called example with no selector.

• It creates an endpoints object called example. This endpoints object is kept up to date with the IPs of the correct network from the pods which appear in example-template.

Limitations

There are some limitations.

• This isn't production quality and has had limited testing.

• The build process (install operator-sdk, copy in some files) should be cleaned up.

• It only supports headless services. It could clearly be extended to other types, but since not all networks are routable from everywhere in general, adding cluster IP support requires some thought.

• Only IPv4 addresses are included, and only the first one for the network attachment definition (if any).

• The naming (with a hardcoded -template) doesn't feel very robust, and the NetService name for the custom resource is probably not right either.

• The annotation parsing code is frankly a hack, which should probably be replaced with use of the standard client.

• There are a couple of other gotchas in the code tagged with FIXME.