> ## Documentation Index
> Fetch the complete documentation index at: https://alto.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Jinja + YAML

> Augment your YAML with Jinja

## Introduction

Agents are configured using a YAML file. If you're totally new to YAML files, you can
learn more about them [here](https://www.redhat.com/en/topics/automation/what-is-yaml).

In Alto, you can augment your YAML configuration files and Python tasks using Jinja, a
powerful templating language. For example, using Jinja enables you to:

* Create relative variables (e.g., relative paths)
* Use environment variables for production deployments

Here are the list of available Jinja functions:

* `__platform__`
* `__version__`
* `__file__`
* `Path`
* `wkdir()`
* `parent_dir(path)`
* `concat(str1, str2)`
* `env(var)`

We'll cover these next.

## Jinja Functions

<Accordion title="__platform__">
  `{{ __platform__ }}` returns the operating system on which your project is running. It's
  identical to sys.platform. You probably won't use this much in your projects.

  Example:

  ```yaml alto.yml theme={null}
  "my-agent-{{ platform }}":
    infra:
      type: ec2
      ...
  ```
</Accordion>

<Accordion title="__version__">
  `{{ __version__ }}` returns the Python version on which your project is running, in
  the format `"{major}.{minor}.{micro}"`. As with `__platform__`, you probably won't use
  this much in your projects.

  Example:

  ```yaml alto.yml theme={null}
  "my-agent-{{ version }}":
    infra:
      type: ec2
      ...
  ```
</Accordion>

<Accordion title="__file__ and Path">
  `{{ __file__ }}` allows you to access the the path to the YAML file.

  `{{ Path(...) }}` allows you convert any string to a pathlib
  [Path](https://docs.python.org/3/library/pathlib.html) object. When using this Jinja
  function, users also get access to Path's methods and operators.

  `{{ __file__ }}` and `{{ Path(...) }}` can be used together to define relative paths.

  Example:

  ```yaml alto.yml theme={null}
  my_cloud_agent:
    infra:
      type: ec2
      instance_type: t2.micro
      ami_image: ami-01c647eace872fc02
    entrypoint:
      type: function
      cmd: main.write_txt_file
      kwargs:
        output_dir: "{{ Path(__file__) / 'output' }}"
  ```
</Accordion>

<Accordion title="wkdir()">
  `{{ wkdir() }}` allows you to access the current project directory as a string. This is a
  less powerful alternative to `{{ Path(__file__) }}`.

  Example:

  ```yaml alto.yml theme={null}
  my_cloud_agent:
    infra:
      type: ec2
      instance_type: t2.micro
      ami_image: ami-01c647eace872fc02
    entrypoint:
      type: function
      cmd: main.write_txt_file
      kwargs:
        output_dir: "{{ wkdir() }}/output"
  ```
</Accordion>

<Accordion title="parent_dir()">
  `{{ parent_dir(path) }}` computes the parent path of path as a string. This is a less
  powerful alternative to `{{ Path(__file__).parent }}`.

  Example:

  ```yaml alto.yml theme={null}
  my_cloud_agent:
    infra:
      type: ec2
      instance_type: t2.micro
      ami_image: ami-01c647eace872fc02
    entrypoint:
      type: function
      cmd: main.write_txt_file
      kwargs:
        output_dir: "{{ parent_dir(wkdir()) }}"
  ```
</Accordion>

<Accordion title="concat()">
  `{{ concat(str1, str2) }}` concatenates str1 and str2 together and returns the
  output as a string.

  Example:

  ```yaml alto.yml theme={null}
  my_cloud_agent:
    infra:
      type: ec2
      instance_type: t2.micro
      ami_image: ami-01c647eace872fc02
    entrypoint:
      type: function
      cmd: main.write_txt_file
      kwargs:
        output_dir: "{{ concat(parent_dir(wkdir()), '/output') }}"
  ```
</Accordion>

<Accordion title="env()">
  `{{ env(var) }}` returns the environment variable var. This is probably the most
  useful Jinja function.

  Example:

  ```yaml alto.yml theme={null}
  my_cloud_agent:
    infra:
      type: ec2
      instance_type: t2.micro
      ami_image: ami-01c647eace872fc02
    entrypoint:
      type: function
      cmd: main.write_txt_file
      kwargs:
        output_dir: "{{ Path(__file__).parent / 'output' }}" 
    requirements: requirements.txt
    env:
      AWS_ACCESS_KEY_ID: "{{ env('AWS_ACCESS_KEY_ID') }}"
      AWS_SECRET_ACCESS_KEY: "{{ env('AWS_SECRET_ACCESS_KEY') }}"
      AWS_DEFAULT_REGION: "{{ env('AWS_DEFAULT_REGION') }}"
  ```
</Accordion>