support fieldSelector for Informer

[andekande]

In order to watch a resource list that is protected by a role on the resource name, we must be able to specify that name as fieldselector both in the request to watch (client-node.makeInformer()) and list (coreV1Api.listNamespaced[Resource]).

This is documented here: https://kubernetes.io/docs/reference/access-authn-authz/rbac/#referring-to-resources

If you restrict list or watch by resourceName, clients must include a metadata.name field selector in their list or watch request that matches the specified resourceName in order to be authorized.

An example is outlined explained in broader detail in the accompanying PR: kubernetes/website#29468

This is code to verify the desired state:

const k8s = require('@kubernetes/client-node');
const fs = require('fs')
const kc = new k8s.KubeConfig();
kc.loadFromDefault();
const k8sCoreApi = kc.makeApiClient(k8s.CoreV1Api);
const listFn = () => this.k8sCoreApi.listNamespacedSecret("myNamespace", undefined, undefined, undefined, "metadata.name=mySecret");
const informer = k8s.makeInformer(kc, "/api/v1/namespaces/myNamespace/secrets", listFn, undefined, "metadata.name=mySecret");

informer.on(k8s.ERROR, (err) => {
    console.error(err);
    // winding up with a 403 if fieldSelector is not specified for the makeInformer request
    // the list request is okay though
});

informer.start();

Currently this code produces:

Error: Forbidden
    at Request.<anonymous> (/app/beb-luigi-core/node_modules/@kubernetes/client-node/dist/watch.js:23:31)
    at Request.emit (events.js:314:20)
    at Request.onRequestResponse (/app/beb-luigi-core/node_modules/request/request.js:1059:10)
    at ClientRequest.emit (events.js:314:20)
    at HTTPParser.parserOnIncomingClient [as onIncoming] (_http_client.js:601:27)
    at HTTPParser.parserOnHeadersComplete (_http_common.js:122:17)
    at TLSSocket.socketOnData (_http_client.js:474:22)
    at TLSSocket.emit (events.js:314:20)
    at addChunk (_stream_readable.js:297:12)
    at readableAddChunk (_stream_readable.js:272:9) {
  statusCode: 403
}

When this role is in use:

apiVersion: rbac.authorization.k8s.io/v1
kind: Role
metadata:
  name: secret-role
  namespace: myNamespace
rules:
  - apiGroups: [""]
    resources: ["secrets"]
    resourceNames: [ "mySecret" ]
    verbs: ["watch", "get", "list"]
```

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: andekande / name: Jan Hesse (e0127b4, eb4d246, 57c6bfc)

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[brendandburns]

/lgtm
/approve

Thanks for the PR (and special thanks for writing unit tests!)

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[andekande]

Thanks for the PR (and special thanks for writing unit tests!)

Thanks for the excellent first-contributor experience!