# Customize doctor diagnostic checks

Even though `wp doctor` comes with a [number of default diagnostic checks](/link/240), it's designed with extensibility at its core. Checks are defined at runtime, read from a `doctor.yml` configuration file naming each check with its options.

## doctor.yml format

Let's take a look at the first two checks in the included `doctor.yml`:

    autoload-options-size:
      check: Autoload_Options_Size
    constant-savequeries-falsy:
      check: Constant_Definition
      options:
        constant: SAVEQUERIES
        falsy: true


In this example:

*   'autoload-options-size' and 'constant-savequeries-falsy' are the _names_ for the checks. Names must be unique amongst all registered checks.
*   `Autoload_Options_Size` and `Constant_Definition` are reusable check classes in the `runcommand\Doctor\Checks` namespace. You can use them too, or you can write your own class extending `runcommand\Doctor\Checks\Check` and supply it as 'class: yourNamespace\\yourClassName'.
*   'constant' and 'falsy' are configuration options accepted by the `Constant_Definition` class. In this case, we're telling doctor to ensure `SAVEQUERIES` is either false or undefined.

For the sake of completeness, it's also worth noting `Autoload_Options_Size` accepts 'threshold\_kb' as an optional configuration option. The default value for 'threshold\_kb' is 900, so it doesn't need to be included in the `doctor.yml`.

## Custom doctor.yml configuration files

Run your own doctor checks by creating a `doctor.yml` and supplying it with `wp doctor check --config=doctor.yml`. Use different configurations for different environments by creating separate `prod.yml` and `dev.yml` files.

If you want your custom file to extend an existing doctor config, you can use the magical `_` config file option to define which config file to inherit. 'default' is a magic reference to the bundled `doctor.yml`; you also specify an entire file path.

Take a look at this example:

    _:
      inherit: default
      skipped_checks:
        - autoload-options-size
    constant-disallow-file-mods-falsy:
      check: Constant_Definition
      options:
        constant: DISALLOW_FILE_MODS
        falsy: true
    plugin-akismet-active:
      check: Plugin_Status
      options:
        plugin: akismet
        status: active
    plugin-akismet-valid-api-key:
      class: Akismet_Valid_API_Key
      require: akismet-valid-api-key.php


This custom `doctor.yml` file:

*   Inherits all default diagnostic checks except for 'autoload-options-size'.
*   Defines a 'constant-disallow-file-mods-falsy' check to ensure the `DISALLOW_FILE_MODS` constant is falsy.
*   Defines a 'plugin-akismet-active' check to ensure Akismet is active.
*   Defines a 'plugin-akismet-valid-api-key' [custom check in a akismet-valid-api-key.php file](/link/254) to ensure Akismet has a valid API key.

## Available check types

Some `wp doctor` check types are configurable, meaning the default setting can be changed, while other check types are abstracted in such a way that they can be reusable. For instance, the `Autoload_Options_Size` check accepts an option 'threshold\_kb' while `Plugin_Status` accepts 'plugin' and 'status' as options.

The configurable check types include:

*   `check: Autoload_Options_Size`: Accepts 'threshold\_kb' as an option to set the threshold in kilobytes. Default value is 900.
*   `check: Cron_Count`: Accepts 'threshold\_count' as an option to set the threshold of total cron jobs. Default value is 50.
*   `check: Cron_Duplicates`: Accepts 'threshold\_count' as an option to set the threshold of duplicate cron jobs. Default value is 10.
*   `check: Plugin_Active_Count`: Accepts 'threshold\_count' as an option to set the threshold of total active plugins. Default is 80.
*   `check: Plugin_Deactivated`: Accepts 'threshold\_percentage' as an option to set the threshold of percentage deactivated plugins. Default is 40.

The abstracted check types include:

*   `check: Constant_Definition`: Assert a given constant as defined, a specific value, or falsy. [Learn more](/link/251).
*   `check: File_Contents`: Check all or a selection of WordPress files for a given regex pattern. [Learn more](/link/253).
*   `check: Option_Value`: Assert a given option as a specific value. [Learn more](/link/252).
*   `check: Plugin_Status`: Assert a given plugin as active, installed, or uninstalled. [Learn more](/link/235).

Of course, some check types don't need configuration options:

*   `check: Core_Update`: Errors when new WordPress minor release is available; warns for major release.
*   `check: Core_Verify_Checksums`: Verifies WordPress files against published checksums; errors on failure.
*   `check: Plugin_Update`: Warns when there are plugin updates available.
*   `check: Theme_Update`: Warns when there are theme updates available.

You can [write your own custom check type](/link/254) by extending the `runcommand\Doctor\Checks\Check` class.