Support Multitenant Services Without Requiring MTX Sidecar Setup

[vlovini]

Is your feature request related to a problem? Please describe.

Yes. The current architecture of the @cap-js/attachments plug-in requires a CAP mtx/sidecar setup to manage tenant subscription and model provisioning in multitenant scenarios. However, this requirement is not technically necessary for Node.js-based services, as the runtime already aligns with what the @sap/cds-mtxs library expects.

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Describe the solution you'd like

We’d like the plug-in to support multitenant services without requiring an MTX sidecar. Specifically:

• Allow the plug-in to register its handlers in the main service runtime, not just in the sidecar.
• Introduce a configuration flag (e.g., in .cdsrc.json) to enable this compatibility explicitly.

This would simplify the architecture and make the plug-in more flexible and compatible with modern deployment strategies.

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Describe alternatives you've considered

• Using the MTX sidecar as required today, but this introduces complexity
• Attempting to patch the plug-in to bypass the sidecar check (e.g.,

  attachments/lib/mtx/server.js

  Line 222 in 4a1ec2d

  if (profile === 'mtx-sidecar') {

  ), but this is not maintainable long-term.

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Additional context

• The current check for sidecar usage appears to be based on a profile flag, not a hard technical limitation.
• A related feature request has been created for the underlying MTXS library to support batch multi-tenant operations: [cds-mtxs] Support Batch Multi-Tenant Operations in CAP MTX Endpoints.
• Documentation reference for DWC CF task behavior:
  https://pages.github.tools.sap/deploy-with-confidence/solar-system/how-to-guides/application-development/development/nodejs_cap#cds-database-setup=multitenancy--using-euporie-for-onboarding-offboarding-and-upgrading-tenants-databases

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Have you already checked existing issues before creating a feature request?

Yes.

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Customer Info

Company: SAP