# atmos aws cloudformation validate

Validate the component's template with CloudFormation's server-side
`ValidateTemplate` API — a syntax and capability-discovery check, not a local
linter.

> ⚠️ Experimental

## Usage

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

```shell
atmos aws cloudformation validate vpc -s plat-ue2-dev
```

Validate all or affected components in dependency order:

```shell
atmos aws cloudformation validate --all -s plat-ue2-dev
atmos aws cloudformation validate --affected --base origin/main
```

Validate components filtered by tags or labels (composes with `--all`/`--affected` to narrow the selected set further):

```shell
atmos aws cloudformation validate --all --tags production,tier-1
atmos aws cloudformation validate --affected --labels cost-center=platform
```

## Flags

- **`--stack`, `-s` (required for a single component)**
  Atmos stack. Required when operating on a single component; optional (and used only to narrow the selected set) with 
  `--all`
  /
  `--affected`
  .

:::note
`validate` only checks template syntax and discovers required capabilities
(e.g. `CAPABILITY_IAM`) via the AWS API. It does not run local linters such as
`cfn-lint` or `cfn-guard` — declare those tools via the
[toolchain subsystem](/cli/configuration/toolchain) and run them from
[hooks](/stacks/hooks) or workflow steps if you want that check.
:::