# atmos stack set

Set a component-relative value for a component in a stack. Atmos uses provenance to
find the manifest file that defines the effective value and edits that file in place,
preserving comments, anchors/aliases, Atmos YAML functions, and Go templates.

:::note Deprecated alias
Use `atmos stack config set`. This hidden alias retains its existing configuration-editing behavior until a breaking release.
:::

:::info
`atmos stack set` is an alias for [`atmos stack config set`](/cli/commands/stack/config/set), the canonical form.
:::

## Usage

```shell
atmos stack set <path> <value> -s <stack> -c <component> [--type <type>] [--file <manifest>]
```

## Examples

```shell
# Set the value where it currently resolves from. Component vars have no fixed
# schema, so --type=auto (the default) infers from the value already there --
# a bool/int stays a bool/int, not a quoted string.
atmos stack set vars.region us-west-2 -s plat-ue2-prod -c vpc

# A brand-new vars.<name> key with nothing existing to infer from still infers
# correctly if the component's variables.tf declares a type for it -- writes
# an unquoted number, not the string "3", because `variable "replicas" { type
# = number }` says so. This also retypes an existing value if it disagrees
# with the declared type (e.g. a number stored as a quoted string).
atmos stack set vars.replicas 3 -s plat-ue2-prod -c vpc

# Explicit --type skips inference (needed for a brand-new key with nothing to
# infer from, or to override).
atmos stack set settings.spacelift.workspace_enabled true --type=bool -s plat-ue2-prod -c vpc

# Edit (or create the key in) a specific manifest. A brand-new key with no
# Terraform-declared type still infers from its own shape -- "true" is
# written as a bool here, not the literal string "true".
atmos stack set vars.new_flag true --file stacks/deploy/prod.yaml -s plat-ue2-prod -c vpc
```

## Arguments

- **`<path>` (required)** — Component-relative dot-notation path (e.g. `vars.region`).
- **`<value>` (required)** — The value to set, interpreted according to `--type`.

## Flags

- **`--stack` / `-s` (string, required)** — The stack name.
- **`--component` / `-c` (string, required)** — The component name.
- **`--type` (string, default `auto`)** — How to interpret `<value>`: `auto` (infer from the component's declared Terraform variable
  type for `vars.*` paths, then from the type of the value already at the path, then from the new
  value's own shape, falling back to string with a warning), `string`, `int`, `bool`, `float`,
  `null`, or `yaml` (raw literal).
- **`--file` (string)** — Edit this manifest explicitly instead of resolving via provenance. Required when the value is not yet defined anywhere; can also be used to create new keys.

:::note
Edits that would alter or expand a YAML anchor or alias are rejected to avoid silently
mutating shared data, as are multi-document manifests and manifests that define the
same anchor name more than once. Comments, anchors, indentation width, and line
endings (CRLF/LF) are preserved, but blank lines between entries are dropped and
non-indented sequence styles are normalized when a file is edited.
:::