Syntax error on startup and regular job polling in multitenant application

[neilprince]

I am experiencing an error when the CAP service starts and on the regular polling defined with parameter runInterval. The call stack of the syntax error is:

[mtx] - Failed to parse metadata to JSON {
  error: SyntaxError: "undefined" is not valid JSON
      at JSON.parse (<anonymous>)
      at SaasProvisioningService._toMetadataJson (C:\wa-cap-js\myEventQueue\node_modules\@sap\cds-mtxs\srv\cf\abstract-provisioning-service.js:93:19)
      at C:\wa-cap-js\myEventQueue\node_modules\@sap\cds-mtxs\srv\cf\abstract-provisioning-service.js:112:92
      at Array.map (<anonymous>)
      at SaasProvisioningService._read (C:\wa-cap-js\myEventQueue\node_modules\@sap\cds-mtxs\srv\cf\abstract-provisioning-service.js:112:8)
      at process.processTicksAndRejections (node:internal/process/task_queues:95:5)
      at async next (C:\wa-cap-js\myEventQueue\node_modules\@sap\cds\lib\srv\srv-dispatch.js:57:17)
      at async SaasProvisioningService.handle (C:\wa-cap-js\myEventQueue\node_modules\@sap\cds\lib\srv\srv-dispatch.js:55:10)
      at async _getAllTenantBase (C:\wa-cap-js\myEventQueue\node_modules\@cap-js-community\event-queue\src\shared\cdsHelper.js:137:10)
      at async Object.getAllTenantIds (C:\wa-cap-js\myEventQueue\node_modules\@cap-js-community\event-queue\src\shared\cdsHelper.js:141:20),
  metadata: undefined
}
[/eventQueue/runner] - updating of periodic events is disabled or no periodic events configured { updateEnabled: true, events: 0 }

event-queue is executing function _getAllTenantBase which connects to the cds.xt.SaasProvisioningService\tenant endpoint to read tenant details

const _getAllTenantBase = async () => {
  if (!config.isMultiTenancy) {
    return null;
  }

  // NOTE: tmp workaround until cds-mtxs fixes the connect.to service
  for (let i = 0; i < 10; i++) {
    if (cds.services["cds.xt.SaasProvisioningService"] || cds.services["saas-registry"]) {
      break;
    }
    await new Promise((resolve) => setTimeout(resolve, 1000).unref());
  }

  const ssp = await cds.connect.to("cds.xt.SaasProvisioningService");
  return await ssp.get("/tenant");
};

The error is then thrown from @sap\cds-mtxs\srv\cf\abstract-provisioning-service.js in function _read on this code:

    return (await cds.tx({ tenant: t0 }, tx =>
      tx.run(SELECT.from(Tenants).columns(['ID', 'metadata', 'createdAt', 'modifiedAt']))
    )).map(({ ID, metadata, createdAt, modifiedAt }) => ({ subscribedTenantId: ID, ...this._toMetadataJson(metadata, ID), createdAt, modifiedAt }))

The issue only occurs on HANA. On sqlite, the value in metadata is null so the json parsing does not error. On HANA, the SELECT.from(Tenants) returns uppercase field names for metadata, createdAt and modifiedAt. This is resulting with an undefined value being passed to the JSON parsing function which is resulting in the error. If I change all the field names to uppercase in this function, no syntax error occurs.

I have logged a ticket with SAP on this, but as this is being called through event-queue, they have redirected me to raise an issue here (even though I think it is an issue with mtxs)

I have a private repository that can replicate the error if this is of help.

[soccermax]

Hi,

just to double check: the error does not only occur during startup but by every run based on the runInterval right?
This usually occurs if the CDS model of the cds-mtxs services are not correctly loaded.
As you already mentioned this error is not related to event-queue it's more a setup problem. Does this occur only in your local setup or also on deployed on CF?

[neilprince]

Hi Max

Yes the error occurs on both initial startup and every run based on the runInterval. To provide more detail, it does not occur locally when running with sqlite. It does occur locally when running in hybrid mode bound to the HANA instance. It also has the error when deployed to cloud foundry.

Do you mean a setup problem with mtxs? or event-queue? The app is deployed and am able to subscribe and unsubcribe tenants successfully. The metadata field in the tenants table in the t0 tenant is populated for each subscription.

I can provide access to the repo if that helps.

Regards
Neil

[soccermax]

Hi Neil,

I mean a setup issue with MTXS. It only works by coincidence with SQLite because all database fields are created in lowercase there, whereas in HANA they are uppercase, which requires a mapping.

I remember encountering this problem before, but I can’t recall the exact details. It would be great if you could grant me access to the repository.

Thanks and best regards,
Max

[neilprince]

Hi Max

I just added you to my repo. If you look at branch mtx-no-sidecar you should be able to replicate the issue. I am pretty sure the multitenancy branch (which has a sidecar) is in a state with the same issue as well. I thought I had missed something on the sidecar setup so reverted to a single app with mtxs embedded to test that scenario as well.

It's a repo to test out the plugin and its setup, so happy for it to become permanent and public once cleaned up to assist other users.

Regards
Neil

[soccermax]

Hi Neil

yes its like I thought you're lacking the model of the SaaS Service. Can you please add to cds.requires:

{
"cds.xt.SaasProvisioningService": true
}

[neilprince]

Hi Max

I have added the SaasProvisioningService as requested but it made no difference. I have committed the change to the repo.

I was a bit confused by this as I thought the "multitenancy": true setting was a convenience shortcut to serve both the SaasProvisioningService and the DeploymentService as per capire. I can confirm that the saas-provisioning endpoint is being served:

Any other suggestions?

Regards
Neil