# Autoplanning
On any **new** pull request or **new commit** to an existing pull request, Atlantis will attempt to
run `terraform plan` in the directories it thinks hold modified Terraform projects.

The algorithm it uses is as follows:
1. Get list of all modified files in pull request
1. Filter to those containing `.tf`
1. Get the directories that those files are in
1. If the directory path doesn't contain `modules/` then try to run `plan` in that directory
1. If it does contain `modules/` look at the directory one level above `modules/`. If it
contains a `main.tf` run plan in that directory, otherwise ignore the change.

## Example
Given the directory structure:
```
.
├── modules
│   └── module1
│       └── main.tf
└── project1
    ├── main.tf
    └── modules
        └── module1
            └── main.tf
```

* If `project1/main.tf` were modified, we would run `plan` in `project1`
* If `modules/module1/main.tf` were modified, we would not automatically run `plan` because we couldn't determine the location of the terraform project
    * You could use an [atlantis.yaml](repo-level-atlantis-yaml.html#configuring-planning) file to specify which projects to plan when this module changed
    * Or you could manually plan with `atlantis plan -d <dir>`
* If `project1/modules/module1/main.tf` were modified, we would look one level above `project1/modules`
into `project1/`, see that there was a `main.tf` file and so run plan in `project1/`

## Customizing
If you would like to customize how Atlantis determines which directory to run in
or disable it all together you need to create an `atlantis.yaml` file.
See
* [Disabling Autoplanning](repo-level-atlantis-yaml.html#disabling-autoplanning)
* [Configuring Planning](repo-level-atlantis-yaml.html#configuring-planning)