# Templates

Atmos supports Go templates in stack manifests, along with Sprig and Gomplate functions. Configure template processing and define datasources for dynamic configuration.

## Configuration

Templates are configured in the `templates` section:

**File:** `atmos.yaml`

```yaml
# https://pkg.go.dev/text/template
templates:
  settings:
    enabled: true
    # https://masterminds.github.io/sprig
    sprig:
      enabled: true
    # https://docs.gomplate.ca
    # https://docs.gomplate.ca/functions
    gomplate:
      enabled: true
      experimental: false
      # Timeout in seconds to execute the datasources
      timeout: 5
      # https://docs.gomplate.ca/datasources
      datasources:
        # 'http' datasource
        # https://docs.gomplate.ca/datasources/#using-file-datasources
        ip:
          url: "https://api.ipify.org?format=json"
          # https://docs.gomplate.ca/datasources/#sending-http-headers
          # https://docs.gomplate.ca/usage/#--datasource-header-h
          headers:
            accept:
              - "application/json"
        # 'file' datasources
        # https://docs.gomplate.ca/datasources/#using-file-datasources
        config-1:
          url: "./config1.json"
        config-2:
          url: "file:///config2.json"
```

## Settings

With no [edition pin](/cli/configuration/edition), or a pin on or after `2026-10-26`, stack template processing,
Sprig, and Gomplate default to enabled when omitted from `atmos.yaml`. Earlier editions preserve the disabled
defaults for configurations that omit these keys. Explicit values take precedence over edition defaults.
The fallback used when no CLI configuration file exists already enabled all three and remains unchanged.

- **`templates.settings.enabled`** — A boolean flag to enable/disable the processing of Go templates in Atmos stack manifests. Defaults to `true`. If set to `false`, Atmos will not process Go templates in stack manifests.
- **`templates.settings.sprig.enabled`** — A boolean flag to enable/disable [Sprig Functions](https://masterminds.github.io/sprig/) in Atmos stack manifests. Defaults to `true`.
- **`templates.settings.gomplate.enabled`** — A boolean flag to enable/disable [Gomplate Functions](https://docs.gomplate.ca/functions/) and [Gomplate Datasources](https://docs.gomplate.ca/datasources) in Atmos stack manifests. Defaults to `true`.
- **`templates.settings.gomplate.timeout`** — Timeout in seconds to execute [Gomplate Datasources](https://docs.gomplate.ca/datasources). Defaults to 5. A
  stack manifest can override it in `settings.templates.settings.gomplate.timeout`; otherwise this value applies.
- **`templates.settings.gomplate.experimental`** — Enables experimental Gomplate functions, such as `net.CIDRHost`.
  Defaults to `false`.

  Set globally in `atmos.yaml` or override per stack with `settings.templates.settings.gomplate.experimental`.
  Stacks inherit the global value when omitted; an explicit `false` disables experimental functions for that stack.
  Import templates use the global value. Does not apply to document generation or scaffold templates.
- **`templates.settings.ignore_missing_template_values`** — A boolean flag to globally ignore missing template values across all stack manifest imports. Defaults to `false`.
  When set to `true`, Atmos will not fail if a Go template variable is missing in any imported stack manifest —
  the missing variable will render as an empty string instead of producing an error.
  This is equivalent to setting `ignore_missing_template_values: true` on every individual import, but applied globally.
  The per-import `ignore_missing_template_values` setting takes precedence and can be used to override the global default.

  This is especially useful when importing catalog manifests that use Go templates for external systems (e.g. Datadog)
  where not all template variables need to be provided by Atmos.
  ```yaml title="atmos.yaml"
  templates:
    settings:
      ignore_missing_template_values: true
  ```

## Datasources

The `templates.settings.gomplate.datasources` setting is a map of [Gomplate Datasource](https://docs.gomplate.ca/datasources) definitions:

- The keys of the map are the datasource names, which are used in Go templates in Atmos stack manifests
- The values of the map are the datasource definitions

### Datasource Schema

Each datasource definition supports the following properties:

- **`url`** — The [Datasource URL](https://docs.gomplate.ca/datasources/#url-format). Can be an HTTP URL, file path, or other supported URL schemes.
- **`headers`** — A map of [HTTP request headers](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers) for the [`http` datasource](https://docs.gomplate.ca/datasources/#sending-http-headers). The keys of the map are the header names. The values of the map are lists of values for the header.

### Using Datasources in Templates

```yaml
terraform:
  vars:
    tags:
      provisioned_by_ip: '{{ (datasource "ip").ip }}'
      config1_tag: '{{ (datasource "config-1").tag }}'
      config2_service_name: '{{ (datasource "config-2").service.name }}'
```

## Available Template Functions

Atmos supports the following template functions and data sources:

- [Go `text/template` functions](https://pkg.go.dev/text/template#hdr-Functions)
- [Atmos Template Functions](/functions/template)
- [Sprig Functions](https://masterminds.github.io/sprig/)
- [Gomplate Functions](https://docs.gomplate.ca/functions/)
- [Gomplate Datasources](https://docs.gomplate.ca/datasources/)

:::tip
For more details, refer to [Atmos Stack Manifest Templating](/templates)
:::

## Function Conflicts

:::warning
Some functions are present in both [Sprig](https://masterminds.github.io/sprig/) and [Gomplate](https://docs.gomplate.ca/functions/).

For example, the `env` function has the same name in [Sprig](https://masterminds.github.io/sprig/os.html) and [Gomplate](https://docs.gomplate.ca/functions/env/), but has different syntax and accepts different numbers of arguments.

If you use the `env` function from one templating engine and enable both [Sprig](https://masterminds.github.io/sprig/) and [Gomplate](https://docs.gomplate.ca/functions/), it will be invalid in the other templating engine, and an error will be thrown.

For this reason, you can use the `templates.settings.sprig.enabled` and `templates.settings.gomplate.enabled` settings to selectively enable/disable the [Sprig](https://masterminds.github.io/sprig/) and [Gomplate](https://docs.gomplate.ca/functions/) functions.
:::

### Removed and Renamed Gomplate Functions

Atmos embeds Gomplate v5. Functions that Gomplate deprecated in v3 were removed upstream in v4, so templates written
against older Atmos releases reference names that no longer exist in Gomplate itself. Atmos keeps every one of them
working through a compatibility shim: the old name still runs with its Gomplate v3 behavior and logs a warning naming
the replacement to switch to. The replacement is not always a drop-in: some take their arguments in a different order
or return a different type, as noted for each function below. A bare alias that Sprig provides (such as `contains`)
resolves to Sprig without a warning, as it did before.

A stack manifest rendered as a whole (for example, an import with `context`) is named in the warning, once per manifest
per function. Component configuration is rendered after Atmos merges every manifest that contributes to it, so there is
no single manifest to name: those warnings appear once per function per run, under the name of the rendering step.
Search your stacks for the function name to find each call. The shim is a bridge, not a long-term guarantee — it will
be removed in a future major release of Atmos, so treat the warning as a to-do, not background noise. Each removed
function has a direct replacement:

- **`conv.Bool`** — Use [`conv.ToBool`](https://docs.gomplate.ca/functions/conv/#convtobool).
- **`conv.Slice`, `conv.Dict`, `conv.Has`** — Use [`coll.Slice`](https://docs.gomplate.ca/functions/coll/#collslice), [`coll.Dict`](https://docs.gomplate.ca/functions/coll/#colldict), and [`coll.Has`](https://docs.gomplate.ca/functions/coll/#collhas).
- **`strings.Sort`** — Use [`coll.Sort`](https://docs.gomplate.ca/functions/coll/#collsort).
- **`net.ParseIP`, `net.ParseIPPrefix`, `net.ParseIPRange`** — Use [`net.ParseAddr`](https://docs.gomplate.ca/functions/net/#netparseaddr), [`net.ParsePrefix`](https://docs.gomplate.ca/functions/net/#netparseprefix), and [`net.ParseRange`](https://docs.gomplate.ca/functions/net/#netparserange). The old names still work, warn, and return their v3 types (`netaddr.IP`, `netaddr.IPPrefix`, and `netaddr.IPRange`), so their methods keep working. The replacements return `netip.Addr`, `netip.Prefix`, and `netipx.IPRange`, which have different methods.
- **`slice`, `contains`, `hasPrefix`, `hasSuffix`, `split`, `splitN`, `trim` (bare aliases)** — Gomplate no longer registers these unqualified names. Use the namespaced forms (`coll.Slice`, `strings.Contains`,
  `strings.HasPrefix`, `strings.HasSuffix`, `strings.Split`, `strings.SplitN`, `strings.Trim`), and check the
  argument order when you switch. Gomplate's bare aliases, and the Atmos shims that serve them when Sprig is disabled,
  take the input first; the `strings.*` functions take it last so they work in pipelines. For example,
  `contains "alphabet" "pha"` becomes `strings.Contains "pha" "alphabet"`, and `splitN "a,b,c" "," 2` becomes `strings.SplitN "," 2 "a,b,c"`. `coll.Slice` takes the same arguments as `slice`.

  When `templates.settings.sprig.enabled` is `true` (the default), the bare `slice`, `contains`, `hasPrefix`,
  `hasSuffix`, `split`, and `trim` names keep working through [Sprig](https://masterminds.github.io/sprig/), which defines functions
  of the same name (note that Sprig's argument order differs from Gomplate's in some cases) — Atmos doesn't warn in
  that case, since Sprig owns the name and nothing changed. With Sprig disabled, Atmos's compatibility shim serves
  the old Gomplate argument order and warns instead. The bare `slice` name works the same way: Sprig's `slice` when
  Sprig is enabled, and Gomplate's `slice` (build a list from its arguments, not Go's builtin) with a warning when
  Sprig is disabled. There is no Sprig fallback for `splitN`, so the shim covers it either way.

Two further upstream changes affect existing templates:

- Conversion functions such as `conv.ToInt64`, `conv.ToFloat64`, and `conv.Atoi` (and the functions built on them) now return an error on input they cannot convert, instead of silently returning `0`. Atmos does not restore the old silent-zero behavior; the error message includes a hint to guard the call with `if` or a default.
- The `regexp.*` functions return an error for an invalid pattern instead of panicking.

Two datasource behaviors also changed upstream. Atmos can't emulate either one, so instead it warns when it recognizes
the pattern in your stack manifests, naming the fix:

- An `aws+smp://` (AWS SSM Parameter Store) datasource now returns the parameter value directly instead of a struct
  with a `Value` field. Drop the trailing `.Value` from calls like `(ds "param").Value`; add `?type=application/json`
  to the datasource URL if you need the value parsed as JSON.
- A sub-path argument to `ds`/`datasource`/`include` (for example `ds "config" "nested/file.yaml"`) is now resolved as
  a relative URL against the datasource's own URL, so the datasource URL must end with `/` to be treated as a
  directory.

The `boltdb://` datasource scheme was removed upstream with no replacement; Atmos warns if a configured datasource
still uses it.

Gomplate v5 also adds the [`semver.*`](https://docs.gomplate.ca/functions/semver/) namespace for parsing and comparing semantic versions.

## See Also

- [CLI Configuration](/cli/configuration) — Overview of CLI configuration
- [Stack Manifest Templating](/templates) — Complete guide to using templates in stacks
- [Template Functions](/functions/template) — Atmos-specific template functions