## How cross-account access works

URL: https://docs.atlan.com/apps/connectors/etl-tools/aws-glue/concepts/how-cross-account-access-works

> Learn how Atlan reads your AWS Glue Data Catalog - the traffic path, the two ways of proving identity, and the two-key door that makes role-based access safe.

This page explains how Atlan reads your Glue Data Catalog: the traffic path, the two ways of proving identity, and the "two-key door" that makes role-based access safe - and that causes the most support issues when half-finished. No prior AWS knowledge is required.

For the architecture view of direct and self-deployed runtime connectivity, see [How Atlan connects to AWS Glue](https://docs.atlan.com/llms/connectors/aws-glue/how-atlan-connects-to-aws-glue/llms.txt).

## Visitor badge

Think of your AWS account as an office building and the Glue Data Catalog as its library. Atlan needs to walk in and read the card catalog - never the books themselves (Glue crawling is **metadata only**).

There are two ways to let a visitor in:

- **IAM access keys** are like handing Atlan a permanent staff badge. Simple - but if the badge is ever reprinted (keys rotated) and you forget to give Atlan the new one, Atlan is locked out mid-crawl.
- **A cross-account IAM role** is like a visitor badge printed fresh at reception for every visit. Atlan shows its own government ID (its AWS identity, called the *node instance role*), reception checks the visitor list, and issues a badge that expires within hours. Nothing permanent ever leaves the building.

The visitor-badge system has a catch: **two separate lists must both name the visitor**. Your building's visitor list (the *trust policy* on your role) and Atlan's own outbound register (the *allowlist* on Atlan's side). Miss either one and the door stays shut.

## Traffic path

![Diagram of cross-account access from your Atlan tenant to your AWS account: the Glue crawler workflow, using the node instance role (Atlan's ID card, one per tenant), asks AWS STS "May I assume it?"; STS issues a temporary badge after checking both allowlists against your IAM role for Atlan (trust policy = the visitor list); Atlan then makes Glue API calls with the temporary badge (TLS, metadata only) to the Glue Data Catalog - databases, tables, columns per region - where Lake Formation, if enabled, can silently filter what the APIs return](https://docs.atlan.com/img/apps/connectors/etl-tools/aws-glue/how-tos/glue-cross-account-access-flow.png)

The cross-account flow. With access keys, steps 1–2 are replaced by the key pair - the Glue API path (3) and the Lake Formation filter are identical.

1. **Atlan asks AWS to assume your role.** Atlan's node instance role calls AWS STS (the "reception desk").
2. **AWS checks two lists.** Your role's trust policy must name Atlan's node instance role, *and* Atlan's node instance role must be allowed (by Atlan support) to assume your role. Both - this is the two-key door.
3. **Atlan reads the catalog.** With the temporary credentials, Atlan calls `GetDatabases`, `GetTables`, and related read-only APIs. If Lake Formation governs your catalog, it filters these responses *silently* - missing grants look like empty results, not errors. See [Catalog permissions & Lake Formation](https://docs.atlan.com/llms/connectors/aws-glue/catalog-permissions-and-lake-formation/llms.txt).

## Glossary

For definitions of every term used in these guides - IAM, IAM role, ARN, trust policy, `sts:AssumeRole`, node instance role, Atlan-side allowlisting, external ID, Glue Data Catalog, Catalog ID, Lake Formation, circuit breaker, preflight checks - see the [Network connectivity glossary](https://docs.atlan.com/llms/governance/administration/network-connectivity-glossary/llms.txt).

## See also

- [Choose how Atlan connects to AWS Glue](https://docs.atlan.com/llms/connectors/aws-glue/choose-how-atlan-connects-to-aws-glue/llms.txt): Pick the right method before configuring anything
- [Connect with cross-account IAM role](https://docs.atlan.com/llms/connectors/aws-glue/connect-with-a-cross-account-iam-role/llms.txt): Apply this knowledge in the recommended setup

_Last updated: 20 August 2026._

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