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Signed-off-by: Ilia Gogotchuri <ilia.gogotchuri0@gmail.com> Co-authored-by: Oleksandr Levchenkov <ollevche@gmail.com>
72 lines
2.5 KiB
Plaintext
72 lines
2.5 KiB
Plaintext
---
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description: >-
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An introduction to the functions which can be used to transform and
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combine values in expressions.
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---
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# Functions
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## Built-in Functions
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The OpenTofu language includes a number of built-in functions that you can
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call from within expressions to transform and combine values. The general
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syntax for function calls is a function name followed by comma-separated
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arguments in parentheses:
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```hcl
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max(5, 12, 9)
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```
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For more details on syntax, see
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[_Function Calls_](../../language/expressions/function-calls.mdx)
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in the Expressions section.
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You can experiment with the behavior of OpenTofu's built-in functions from
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the OpenTofu expression console, by running
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[the `tofu console` command](../../cli/commands/console.mdx):
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```
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> max(5, 12, 9)
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12
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```
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The examples in the documentation for each function use console output to
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illustrate the result of calling the function with different parameters.
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## Provider-defined Functions
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As of OpenTofu 1.7.0, providers may define their own functions to be available during
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execution.
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OpenTofu iterates through the [required_providers](../../language/providers/requirements.mdx) block
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and queries the specified providers for any functions they wish to register. Functions are
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added to the current module's context under `provider::<provider_name>::<function_name>`. Provider
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aliases are also supported under `provider::<provider_name>::<provider_alias>::<function_name>`.
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Functions are scoped to the module that requires the provider and are not inherited by child modules.
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### Example:
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```hcl
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terraform {
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required_providers {
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myhelper = {
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# yantrio/helpers registers a function named "echo"
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source = "yantrio/helpers"
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}
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}
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}
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locals {
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myval = provider::myhelper::echo("Hello Functions!")
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}
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```
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### Built-in Provider Functions:
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OpenTofu has a built-in provider `terraform.io/builtin/terraform` which provides [additional functions](../providers/builtin.mdx#functions) that can be used in OpenTofu configurations.
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### Notes for Provider Authors:
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* Support for functions was added in protocol version 5.5 and 6.5.
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* OpenTofu's provider protocol is compatible with Terraform's provider protocol.
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* `GetProviderSchema()` is used to initially query the functions available in a given provider.
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* Providers which supply functions may be configured and may supply additional functions via `GetFunctions()`. See the experimental [Lua](https://github.com/opentofu/terraform-provider-lua) and [Go](https://github.com/opentofu/terraform-provider-go) providers for implementation examples.
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