Monitoring: legacy ES client usages blocking migration of the licensing plugin

[pgayvallet]

So, I tried to migrate the licensing plugin to use the new elasticsearch client (#92143)

I'm currently blocked by the monitoring plugin usage of createLicensePoller:

• The plugin is still using the deprecated createLicensePoller API from the setup method instead of the one from start
• The plugin is creating the legacy ES client using the deprecated core.elasticsearch.legacy.createClient API during its setup phase (there is no equivalent setup API to create new ES clients)

Overall, these two points are causing some huge pain to adapt the call to licensing.createLicensePoller, as creating the new ES client from monitoring's setup method can no longer be synchronous, meaning that we need to either:

• Have the monitoring licensingService be created during start (and passed to the routes created during setup via reference
• Have the monitoring licensingService receive a promise of an ES client and change its APIs from synchronous to asynchronous
• Cleanup the MonitoringPlugin.getLegacyShim (no disrespect, but) atrocities and use request handler context to propagate the monitoring licensing service down to the routes.

kibana/x-pack/plugins/monitoring/server/plugin.ts

Lines 102 to 106 in 3b3327d

	const cluster = (this.cluster = instantiateClient(
	config.ui.elasticsearch,
	this.log,
	core.elasticsearch.legacy.createClient
	));

kibana/x-pack/plugins/monitoring/server/plugin.ts

Lines 108 to 115 in 3b3327d

	// Start our license service which will ensure
	// the appropriate licenses are present
	this.licenseService = new LicenseService().setup({
	licensing: plugins.licensing,
	monitoringClient: cluster,
	config,
	log: this.log,
	});

One workaround to unblock the migration of the licensing plugin to the new ES client could be to add a new deprecated createLegacyLicensePoller API that would use a ILegacyClusterClient instead of IClusterClient.

cc @elastic/stack-monitoring-ui @restrry

[elasticmachine]

Pinging @elastic/kibana-core (Team:Core)

[mshustov]

Cleanup the MonitoringPlugin.getLegacyShim (no disrespect, but) atrocities and use request handler context to propagate the monitoring licensing service down to the routes.

It'd say it's time to get rid of the legacy wrapper. Monitoring plugin must migrate to the new ES client before v8.0 anyway #83910 , which will force the plugin to move ES client instantiation to start lifecycle.

@chrisronline @igoristic Is this work planned any time soon? Is it possible to refactor licensingService to unblock @pgayvallet work?

[chrisronline]

@restrry I'm investigating solutions in #93620

[chrisronline]

@restrry #93620 should handle unblocking the license service. We'll do the work to refactor the legacy createClient usage in a separate PR.

[simianhacker]

The plugin is still using the deprecated createLicensePoller API from the setup method instead of the one from start

Is there a replacement API we should be using that will accept a IClusterClient? There seems to be a discrepancy between the type definition and the implementation.

  createLicensePoller: (
    clusterClient: IClusterClient,
    pollingFrequency: number
  ) => { license$: Observable<ILicense>; refresh(): Promise<ILicense> };

vs

  private createLicensePoller(clusterClient: ILegacyClusterClient, pollingFrequency: number) {

OR should I just update createLicensePoller and fetchLicense to use the new IClusterClient interface?

[mshustov]

@simianhacker should be done in #92143 @pgayvallet any ETA for this?

[pgayvallet]

any ETA for this?

There wasn't, but if we're unblocked, I will try to do it asap.

Need to take a look to check if #93620 solves all we need to unblock the licensing migration. Planning to take a look this week.