> ## Documentation Index
> Fetch the complete documentation index at: https://docs.oncost.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Connect GCP

> Set up GCP cost collection via BigQuery billing export

# Connect GCP

oncost collects GCP costs via the BigQuery billing export. Setup takes about 10 minutes.

## Prerequisites

* A GCP project with billing enabled
* Permission to create service accounts and enable BigQuery billing export

## Step 1: Enable billing export to BigQuery

If you don't already have billing export enabled:

1. Go to **GCP Console > Billing > Billing export**
2. Click **Edit settings** under BigQuery export
3. Select a project and dataset (create a new dataset if needed, e.g., `billing_export`)
4. Select **Detailed usage cost** export type
5. Click **Save**

GCP starts populating data within a few hours.

## Step 2: Create a service account

1. Go to **GCP Console > IAM & Admin > Service Accounts**
2. Click **Create Service Account**
3. Name it (e.g., `oncost-billing-reader`)
4. Grant the role **BigQuery Data Viewer** on the billing dataset
5. Grant the role **BigQuery Job User** on the project
6. Click **Done**
7. Create a JSON key for the service account and download it

## Step 3: Complete the connection

In oncost, go to **Settings > Connections > New Connection > GCP**:

1. Upload or paste the **service account JSON key**
2. Enter the **BigQuery dataset** name (e.g., `project-id.billing_export`)
3. Click **Test Connection** to verify access
4. Click **Save**

## What oncost collects

* Daily cost breakdown by service, SKU, project, and region
* Usage quantities and units
* Labels applied to resources
* Credits and discounts

## Troubleshooting

| Issue               | Fix                                                                                                              |
| ------------------- | ---------------------------------------------------------------------------------------------------------------- |
| "Permission denied" | Verify the service account has BigQuery Data Viewer on the billing dataset and BigQuery Job User on the project. |
| No data             | BigQuery export can take a few hours to start. Check the export settings in GCP Console.                         |
| Missing labels      | Labels appear in the billing export automatically. Ensure resources are labeled in GCP.                          |