How to upload files from Bubble to Google Cloud Storage securely: an architecture guide
The short answer
The key design decision is where authorization happens. For a private client portal, a defensible pattern is to let Bubble request upload permission from a server-side integration service. That service verifies the user and organization, assigns a specific object ID, and grants a short-lived way to upload only that object. The browser sends the bytes to Cloud Storage, then the service verifies the stored object and records its state for Bubble to show. The upload is not complete merely because a signed URL was issued or a browser displayed “100%.”
This is a conceptual architecture, not a tested Bubble2X workflow. Bubble2X’s customer-facing Cloud Storage integration is planned. The diagram and sample messages below are illustrative; no production service, file-size limit, performance result, or release date is implied.
The parts you need
In Bubble, you need an authenticated user, a trustworthy relationship between that user and the client organization, a file-selection interface, and a place to show file status. You also need a way for Bubble to call an integration API. Bubble’s API Connector documentation describes outbound API requests. Its security guidance says private connector parameters stay on Bubble’s server when configured correctly and warns against putting credentials in page values or connector defaults.
In Google Cloud, you need a bucket with deliberately scoped access, an identity used by the integration service, and a policy for object retention and deletion. Cloud Storage access control explains the available permission systems. Uniform bucket-level access makes IAM the access-control system for a bucket by disabling object ACLs. The service must have only the operations required by the design; a broad storage administrator role is not a shortcut for application authorization.
Finally, you need an integration service or backend that checks requests. Cloud Storage does not understand Bubble’s organization membership. The service must derive the acting user from a trusted mechanism, look up the intended organization, and check that user can create a file there. Never accept “organization_id=cedar” from the browser as proof that the user belongs to Cedar.
A reference request flow
Conceptual diagram
The service should record a pending upload before issuing access. An illustrative authorization request might contain a local file label, declared type, intended organization, and an idempotency key. The service should return an opaque upload ID, expected object ID, expiry, and temporary upload mechanism. The exact fields and transport depend on the tested implementation; they are not a Bubble2X API contract.
The browser may use a signed URL for a specific object and HTTP method. Google’s signed URL documentation is explicit that anyone holding an active URL can use it. Keep the URL short-lived, transmit it only over HTTPS, and avoid logging it. The service must check the application user’s rights before issuing it. A signed URL by itself does not bind a storage request to a Bubble user or tenant.
For a browser-direct request, inspect Cloud Storage CORS behavior. A browser’s cross-origin rules can block a request even when the storage permission is otherwise valid. Configure only the required origins, methods, and headers for the chosen Cloud Storage endpoint, and test both authorized and unauthorized origins. CORS is a browser interaction rule; it is not the tenant authorization system.
Object naming, overwrite protection, and limits
Give each upload a server-assigned, opaque object name. A path may include a non-sensitive organization key and a random file ID for operations, but the path itself should never be the sole security control. Keep the user-supplied filename as display metadata after sanitization, not as the unique storage key. That reduces collision risk and avoids revealing customer names in object paths and logs.
Decide what should happen if an object already exists. Cloud Storage generation preconditions include a create-only condition that fails when a live object is already present. A tested implementation can use a precondition where the chosen upload method supports it. Alternatively, generate unguessable new object IDs and reject duplicate finalization. Either way, test repeat submissions and retries so a client cannot overwrite another file by choosing a familiar name.
Set a declared size and type policy when the service authorizes an upload, then verify the actual stored object afterward. A file’s extension or browser-declared MIME type is not proof of its contents. If the use case requires content inspection or malware scanning, place the file in a pending state until the required check finishes; define what happens to rejected files. The exact enforcement options differ by upload method. Do not claim that every signed URL automatically enforces a maximum size. Google Cloud also documents signed policy documents for HTML form uploads with policy conditions; evaluate that approach separately if browser-side constraints are required.
What “upload complete” should mean
The browser knows whether its transfer request finished, but it cannot be the authority on whether the expected object was stored, belongs to the intended upload, and passed the application’s validation. Let the service inspect Cloud Storage metadata for the exact object ID, compare the expected and observed size or type where appropriate, and record a terminal outcome. Then Bubble can poll or receive a safe status update. A file should not appear as downloadable while it is merely authorized or awaiting validation.
Use an idempotency key for authorization and finalization. If the user clicks twice or the browser retries after losing a response, the service should return the same pending upload or an intelligible conflict, not issue multiple indistinguishable grants. Define expiry for unused grants. If an object was uploaded but finalization never arrived, a reconciliation job can inspect the pending record and object metadata before deciding whether to finalize, reject, or clean it up.
Separate user-facing states such as “ready to upload,” “uploading,” “checking file,” “available,” and “failed.” The upload-status guide develops these states and recovery messages. Avoid treating a timeout as proof of failure: the bytes may have arrived even if Bubble did not receive confirmation.
Direct upload versus a server-mediated byte path
A direct browser-to-Cloud-Storage path can keep large file bytes away from the integration service. It also means the browser receives a temporary storage grant, so URL handling, CORS, size policy, and completion verification need careful testing. A server-mediated path sends the bytes through your service. That gives the service more immediate control over request handling and content inspection, but it must now handle bandwidth, memory, streaming, timeouts, retries, and additional transfer costs. Neither pattern is universally safer or cheaper; compare it using expected file sizes, clients, inspection needs, and the agency’s operational capacity.
Bubble’s own private-file features may be sufficient for a portal without an external storage requirement. Before adding Google Cloud, write down what the external design solves: a specific ownership model, downstream processing need, customer requirement, or storage lifecycle. A new bucket and service add another system to secure, monitor, and support.
A test plan before publishing instructions
Run this design with synthetic Cedar and Harbor organizations in a disposable Bubble app and GCP project. Verify that Cedar can request only its own upload grant. Try a Harbor account, an expired grant, a modified object name, a duplicate upload ID, an oversized file, a mismatched content type, and a browser that never sends finalization. Confirm that a blocked request does not leave a downloadable object or a misleading “available” row. Inspect audit logs for secret URLs and personal data.
Test download and deletion separately. Upload authorization does not authorize later reading. For a download, the service should recheck current membership and issue a separate bounded access mechanism. For deletion, define whether it removes the Bubble record, the Cloud Storage object, or both, and how failures are reconciled. Cloud Storage lifecycle actions are asynchronous, so they should not be presented as immediate deletion.
The operating cost includes Cloud Storage capacity, request operations, network movement, service runtime, monitoring, and human maintenance. A numeric savings claim would need measured traffic and current prices. Record those inputs before choosing a path.
Request early access to discuss your Bubble file-upload workflow. Bubble2X is developing a Google Cloud Storage integration for customer-file workflows.
Related reading: file-upload security checklist and Bubble database versus BigQuery.
