Use within Google Cloud Functions

I wanted to kick off a job in my GKE cluster from a Google Cloud Function reacting to changes in Cloud Storage. Since there's no `.kube/config` it wasn't clear to me how to do that with the new fromKubeConfig initialization. I got it working by piecing together a config object from data retrieved by `google-auth-library` and `@google-cloud/container` clients. I'll leave it here to both ask if this way makes sense and to serve as an example for others trying to do something similar.

```js
const {auth} = require('google-auth-library');
const container = require('@google-cloud/container');
const job = require('./job.json');
const kube = require('kubernetes-client');

const clusterClient = new container.v1.ClusterManagerClient();
const request = {
projectId: process.env.GCLOUD_PROJECT,
zone: 'us-east4-b',
clusterId: 'cluster-2',
};

function getCluster() {
return clusterClient.getCluster(request)
.then(results => {
return results[0];
});
}

function getToken() {
return auth.getClient()
.then(client => {
return client.getAccessToken();
})
.then(tokenResponse => {
return tokenResponse.token;
});
}

// kubeClient is a lazy global used for caching.
// https://cloud.google.com/functions/docs/bestpractices/tips#use_global_variables_to_reuse_objects_in_future_invocations
let kubeClient;

function getKubeClient(cluster, token) {
kubeClient = new kube.Client({config: kube.config.fromKubeconfig({
apiVersion: 'v1',
kind: 'Config',
preferences: {},
'current-context': 'a',
contexts: [
{
name: 'a',
context: {
cluster: 'a',
user: 'a'
}
}
],
clusters: [
{
name: 'a',
cluster: {
'certificate-authority-data': cluster.masterAuth.clusterCaCertificate,
server: `https://${cluster.endpoint}`
}
}
],
users: [
{
name: 'a',
user: {
'auth-provider': {
config: {
'access-token': token,
'cmd-args': 'config config-helper --format=json',
'cmd-path': '/google/google-cloud-sdk/bin/gcloud',
'token-key': '{.credential.access_token}'
},
name: 'gcp'
}
}
}
]
})});
return kubeClient.loadSpec();
}

exports.updateJob = (event) => {
return (kubeClient && Promise.resolve(kubeClient) ||
Promise.all([getCluster(), getToken()]).then(([cluster, token]) => {
return getKubeClient(cluster, token);
}))
.then(kubeClient => {
// Strip extension from filename to get job name
const name = event.data.name.replace(/\.[^/.]+$/, "");
job.metadata.generateName = `${name}-update-`;
job.spec.template.spec.volumes[0].configMap.name = name;
return kubeClient.apis.batch.v1.namespaces('default').jobs.post({body: job});
})
.then(res => {
console.log('Job created:', res.body.metadata.name);
});
};
```

Review the issue's updateJob entry point and job.json example, then trace the config.fromKubeconfig usage with google-auth-library and @google-cloud/container. Decide whether this Google Cloud Functions and GKE setup belongs in the project's documentation, and confirm the documented example works for the described event flow.

Written by the indexing model from the issue text.