refactor: simplify how url generation works

The URLS file is no longer necessary as urls are now generated directly from the app VHOST file.

This also moves all the url generation logic to the domains plugin.

docs/appendices/0.29.0-migration-guide.md

@@ -13,3 +13,5 @@
 - The `DOKKU_WAIT_TO_RETIRE` environment variable has been migrated to a `checks` property named `wait-to-retire` and will be ignored if set as an environment variable.
 - The `Procfile` is now extracted when source code is extracted for a build and not from the built image. Users can specify alternative paths via the `procfile-path` property of the `ps` plugin. See the [process management documentation](/docs/processes/process-management.md#changing-the-procfile-location) for more information on how to configure the `Procfile` path for your application.
 - The `domains-setup` trigger has been removed. Initial app domains will now be automatically setup during app creation.
+- The `URLS` file containing generated urls for an app is no longer generated or referenced. Users should retrieve app urls via the new `domains-urls` plugin trigger.
+- The common function `get_app_urls` has been removed. Users should retrieve app urls via the new `domains-urls` plugin trigger.

docs/development/plugin-triggers.md

@@ -236,6 +236,21 @@ set -eo pipefail; [[ $DOKKU_TRACE ]] && set -x
 # TODO
 ```
 
+### `certs-exists`
+
+- Description: Echos `true` if certs exists for the app, `false` otherwise
+- Invoked by:
+- Arguments: `$APP`
+- Example:
+
+```shell
+#!/usr/bin/env bash
+
+set -eo pipefail; [[ $DOKKU_TRACE ]] && set -x
+
+# TODO
+```
+
 ### `check-deploy`
 
 - Description: Allows you to run checks on a deploy before Dokku allows the container to handle requests.
@@ -713,6 +728,21 @@ set -eo pipefail; [[ $DOKKU_TRACE ]] && set -x
 # TODO
 ```
 
+### `domains-urls`
+
+- Description: Gets an app's url(s)
+- Invoked by:
+- Arguments: `$APP $URL_TYPE`
+- Example:
+
+```shell
+#!/usr/bin/env bash
+
+set -eo pipefail; [[ $DOKKU_TRACE ]] && set -x
+
+# TODO
+```
+
 ### `domains-vhost-enabled`
 
 - Description: Checks if a virtual hosts are enabled for an app