Add the configerator config source doc. (facebookresearch#1190)

* Add configerator config source doc

website/docs/fb/configerator-config-source.md

@@ -0,0 +1,59 @@
+---
+id: fbcode-configerator-config-source
+title: Configerator Config Source Plugin
+---
+
+The ConfigeratorConfigSource plugin makes it possible for Hydra applications to consume a domain of configs from configerator.
+
+### Dependency
+
+Add the following to your `TARGET` file
+```commandline
+//fair_infra/fbcode_hydra_plugins/configerator_config_source:configerator_config_source
+```
+
+### Usage
+
+1. The Configerator Config Source plugin requires that you place the configs under a [domain](https://fburl.com/wiki/n5cgchxe).
+You can find an example domain [here](https://fburl.com/diffusion/ms50g5hu)
+
+:::important
+Due to the limitations of Configerator APIs, matching the name of your domain and directory of configs is necessary for the plugin to extract information on the full config names. 
+For example, the config paths returned by Configerator API could look like `fair_infra/hydra_plugins/configerator_config_source/example/db/mysql`. The plugin needs to know where the directory of configs begins ([`example`](https://fburl.com/diffusion/7c0c5tig)), in order to determine the full config name (`db/mysql`). So in this case the domain should be named [`example.cconf`](https://fburl.com/diffusion/pyymoo1t)
+:::
+
+
+2. Create a [SearchPathPlugin](https://hydra.cc/docs/next/advanced/search_path) to add the Configerator path to the list of search paths.
+   The path you add in your SearchPathPlugin should be the name of your domain of configs, such as in this [example SearchPathPlugin](https://fburl.com/diffusion/ljggtux5)
+
+:::info
+Adding a new search path will become much easier once [#274](https://github.com/facebookresearch/hydra/issues/274) is resolved, which is planned for Hydra 1.1.
+:::
+
+
+### Example:
+
+#### Example SearchPathPlugin
+[`ConfigeratorExampleSearchPathPlugin`](https://fburl.com/diffusion/vwa82fbg) adds the example configerator domain to the search path of the example applications.
+
+#### Reading primary config from configerator
+This example reads its primary config from configerator [here](https://fburl.com/diffusion/twk3smkj) which has a default list defined.
+
+```commandline
+$ buck run //fair_infra/fbcode_hydra_plugins/configerator_config_source/example/primary_config:my_app 
+...
+Parsing buck files: finished in 1.1 sec
+...
+{'driver': 'mysql', 'user': 'alau'}
+```
+
+#### Compose config with configerator
+This example reads its primary config from local yaml file `primary_config.yaml` but reads config groups info from configerator.
+
+```commandline
+$ buck run //fair_infra/fbcode_hydra_plugins/configerator_config_source/example/config_group:my_app -- +db=mysql
+...
+Parsing buck files: finished in 1.1 sec
+...
+{'foo': 'bar', 'driver': 'mysql', 'user': 'alau'}
+```

website/docs/fb/fbcode.md

@@ -16,6 +16,7 @@ title: Hydra at fbcode
 
 ### Facebook specified plugins
  - fbcode_defaults : Changes configuration defaults to be appropriate for fbcode (e.g: Output directories are in `fbcode/outputs` and `fbcode/multirun`)
+ - configerator_config_source: See [doc](/fb/configerator-config-source.md)  for more information.
 
 #### TARGETS
 Hydra includes buck TARGETS you can use in fbcode. In general, if there is TARGET there are two options:

website/sidebars.js

@@ -142,6 +142,7 @@ module.exports = {
             'fb/fbcode',
             'fb/internal-fb-cluster',
             'fb/fair-cluster',
+            'fb/fbcode-configerator-config-source',
         ]),
     }
 }