informer's cache is empty after await informer.start()

[atamon]

Describe the bug
We're migrating from using v0.2X of this library to 1.0, currently 1.0.0-rc7

In the previous version we could rely on informer.list(this.options.namespace) returning the complete list of objects after await informer.start()

With the new version the first call returns undefined.

We use the add, change and delete events to react to changes to this list, and when doing so we can see that the cache/informer is filled up from 0 to N objects.

Is this a new intended behavior, or should it be considered a bug?

Client Version
1.0.0-rc7

Server Version
v1.30.5

To Reproduce

const fn = () => {
    return client.list(
      config.apiVersionLatest,
      config.kind,
      namespace,
    );
  };

  const informer = k8s.makeInformer(
    kubeConfig,
    `/apis/${config.apiVersionLatest}/namespaces/${namespace}/mycrd`,
    fn,
  );

  await informer.start()
  this.informer.list(this.options.namespace) // <- returns undefined, but I would have expected a full cache

Expected behavior
Being able to list all objects directly after the informer.start() promise resolves

Example Code
See steps to reproduce

Environment (please complete the following information):

• OS: Linux
• NodeJS Version v20.18.0
• Cloud runtime GKE

[cjihrig]

I haven't been able to reproduce the issue, but maybe I'm doing something wrong. Are you able to provide a runnable reproduction?

[brendandburns]

I don't know if the example code above is exactly your code for the bug, but I notice that you are using namespace when you create the informer and this.options.namespace when you list from the informer. Is it possible that those two values are different?

The code for the informer is here:

https://github.com/kubernetes-client/javascript/blob/release-1.x/src/cache.ts#L132

And you can see that it does in fact always list and populate the cache on create.

[atamon]

I take it this is not an intended change, and the issue is probably in our code. I'll get back to you when I have looked into this further.

I'll reopen the issue if I can come up with a prop repro. Thanks for the quick support!

[atamon]

Maybe part of my confusion lies within this row:

https://github.com/kubernetes-client/javascript/blob/release-1.x/src/cache.ts#L173

The this.indexCache is only populated for a namespaces if the list actually contains items. Could this in turn lead to this row https://github.com/kubernetes-client/javascript/blob/release-1.x/src/cache.ts#L105 returning undefined until the client has received a non-empty answer within a namespace?

[atamon]

The second part of my confusion had to do with the order of addOrUpdateObject and this.indexObj being called here https://github.com/kubernetes-client/javascript/blob/release-1.x/src/cache.ts#L196

We have code which can be boiled down to this example:

informer.on('add', (obj) => {
  const list = informer.list(namespace) // <- obj will not be included in this list for 1.x, but it was in 0.2
  prometheusMetric.set('myobjs_count', list.length);
});

If I add an await Promise.resolve() line at the top of my callback, I get my expected (but maybe not desired 😛) behaviour:

informer.on('add', async (obj) => {
  await Promise.resolve();
  const list = informer.list(namespace) // <- obj is included in the list
  prometheusMetric.set('myobjs_count', list.length);
});

Having figured out these two cases I think we'll be able to migrate to 1.0 successfully. Great job in your work with the request->fetch migration 😃

[brendandburns]

fwiw, the code at HEAD in the release-1.x branch hasn't actually been released out to NPM yet, it was updated in #1995 so you'll want to either clone and update to HEAD or look at an older version of the code.

It is definitely the case that add events will happen before the full list is populated, since add is called for each object received from the list operation.