# atmos aws cloudformation backend update

Apply configuration changes to the S3 bucket referenced by the component's
resolved `kind: aws/s3` provision target — creating it first if it doesn't
exist yet, then bringing its versioning, encryption, and
public-access-block settings in line with Atmos's secure defaults.
`backend update` and [`backend
  create`](/cli/commands/aws/cloudformation/backend/create) dispatch through
the identical idempotent code path; `update` exists as the explicit,
intention-revealing verb for "make sure this bucket's settings are still
correct."

> ⚠️ Experimental

## Usage

```shell
atmos aws cloudformation backend update <component> --stack <stack> [options]
```

```shell
atmos aws cloudformation backend update vpc -s plat-ue2-dev
```

Disambiguate when the component declares more than one `kind: aws/s3` target:

```shell
atmos aws cloudformation backend update vpc -s plat-ue2-dev --target artifacts
```

## Flags

- **`--stack`, `-s` (required)**
  Atmos stack.
- **`--target` (optional)**
  The 
  `kind: aws/s3`
   provision target to use. Required when more than one is declared.
- **`--identity`, `-i` (optional)**
  Atmos identity to authenticate with.

## Behavior

See [`backend create`](/cli/commands/aws/cloudformation/backend/create) for
the full description of what settings are applied and how the bucket already
existing is handled.