differ

NRI Differ Plugin

The differ plugin can be injected before, after or between other NRI plugins to track and show what changes these other plugins request to containers. The plugin can register itself multiple times at multiple indices, so a single differ instance can be used to track and show step-by-step all the changes made to a container.

Deployment

The NRI repository contains minimal kustomize overlays for this plugin at contrib/kustomize/differ.

Deploy the latest release with:

kubectl apply -k https://github.com/containerd/nri/contrib/kustomize/differ

Deploy a specific release with:

RELEASE_TAG=v0.10.0
kubectl apply -k "github.com/containerd/nri/contrib/kustomize/differ?ref=${RELEASE_TAG}"

Deploy the latest development build from tip of the main branch with:

kubectl apply -k https://github.com/containerd/nri/contrib/kustomize/differ/unstable

Testing

You can test this plugin by registering it to the desired indices (for instance nri-differ --indices 00,20,99 --yaml) in addition to your other plugins that make changes to containers, then starting some containers and examining the results. You should see container modifications printed as yaml-diffs. Make sure you properly inject/register differ both at the front of the plugin chain and after any other plugin.