# atmos aws cloudformation output

Show the deployed stack's `Outputs` (`DescribeStacks`), formatted for
consumption by shells, other tools, or other Atmos components. `apply`
renders this same view automatically at the end of a successful deploy.

> ⚠️ Experimental

**CloudFormation Configuration**

Configure templates, parameters, and delivery targets for your component.
Configuration Reference[Read more](/stacks/components/aws-cloudformation)

## Usage

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

## Examples

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

Print a single Output by its key. The value is written bare, so it is safe to use in a shell
pipeline:

```shell
atmos aws cloudformation output vpc VpcId -s plat-ue2-dev
VPC_ID=$(atmos aws cloudformation output vpc VpcId -s plat-ue2-dev)
```

Choose an output format:

```shell
atmos aws cloudformation output vpc -s plat-ue2-dev --format=json
atmos aws cloudformation output vpc -s plat-ue2-dev --format=env
atmos aws cloudformation output vpc -s plat-ue2-dev --format=github
```

Flatten nested Outputs into compound keys, or uppercase every key:

```shell
atmos aws cloudformation output vpc -s plat-ue2-dev --format=dotenv --flatten --uppercase
```

Show output for all or affected components:

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

With more than one component selected, the JSON and YAML formats print a single document keyed by stack and then by component, so the result stays parseable:

```shell
atmos aws cloudformation output --all --format=json
```

```json
{
  "plat-ue2-dev": {
    "vpc": { "VpcId": "vpc-0123456789abcdef0" },
    "dns": { "ZoneId": "Z0123456789ABCDEFGHIJ" }
  }
}
```

The table format prints a heading naming the component and stack above each table. The other formats print each component's outputs in turn.

## Arguments

- **`component` (required unless `--all`/`--affected`/`--tags`/`--labels` is set)**
  The 
  `aws/cloudformation`
   component.
- **`key` (optional)**

  The Output key to print on its own. With the default `table` format the value is written bare, one line, on stdout.
  With `--format=json` the value is JSON-encoded, with `--format=yaml` YAML-encoded, and the other formats
  render a single `KEY=value`-style entry. A key the stack does not have is an error that lists the
  keys it does have. A key cannot be combined with `--all`, `--affected`, `--tags`, or `--labels`.

## Flags

- **`--stack`, `-s` (required for a single component)**
  Atmos stack. With bulk selection flags, limits the selected components to this stack.
- **`--format` (optional, default `table`)**
  Output format: 
  `json`
  , 
  `yaml`
  , 
  `hcl`
  , 
  `env`
  , 
  `dotenv`
  , 
  `bash`
  , 
  `csv`
  , 
  `tsv`
  , 
  `table`
  , or 
  `github`
  . An unsupported value is an error that names the value and lists the valid formats.
- **`--flatten` (optional)**
  Flatten nested Outputs into compound keys.
- **`--uppercase` (optional)**
  Uppercase Output keys.

:::note
`outputs` is accepted as an alias for `output`.
:::

## Stack state

The `output` command reads the deployed stack, so the stack has to be deployed:

- A stack that is not deployed is an error: `REVIEW_IN_PROGRESS` (a preview changeset created by
  `diff` or `plan` on a component that was never applied), `ROLLBACK_COMPLETE`, `ROLLBACK_FAILED`,
  `CREATE_FAILED`, and the `DELETE_*` statuses. Apply the component, or delete a stack that is stuck in
  a failed create first.
- A deployed stack that declares no `Outputs` prints `Stack <name> has no outputs` instead of an empty
  table. `--format=json` and the other structured formats still print an empty document, so
  pipelines keep getting parseable output.

JSON output is written without HTML escaping, so masked values read `<MASKED>`.

## Masking

With masking enabled, output presentation requires both
`cloudformation:GetTemplate` and `cloudformation:DescribeStacks`.
Atmos reads the deployed template's `NoEcho` metadata, without requiring a
local template or source download.

### Values Masked

- Outputs that reference `NoEcho` parameters, including intrinsic expressions
  and indirect resource or condition dependencies.
- Known parameter and default literals registered for masking.
- A single selected output key, using the same rules as the full output listing.

Unreadable or malformed template metadata stops presentation before values are
printed. Changes to local parameters do not bypass deployed-template masking.

### Limits and Overrides

Use `--mask=false` to disable presentation masking. Internal YAML output
lookups return real values for component dependencies.

Secrets transformed in ways that leave no detectable template reference may
not be recognized. Keep secrets out of CloudFormation outputs.

## Try it out

Requires Docker or Podman, Python 3, and network access for the emulator image. Run against the local AWS emulator; the final commands clean up. No AWS account is needed.

```shell
atmos config set aliases.cft "aws cloudformation"
atmos emulator up aws -s local
atmos cft deploy demo -s local
atmos cft output demo -s local
atmos cft delete demo -s local --auto-approve
atmos emulator down aws -s local
```