FIX: Show detailed errors on CLI for live environments

API: Add HTTPOutputHandler::setCLIFormatter

Fixes https://github.com/silverstripe/silverstripe-framework/issues/6835

This provides detailed errors (but not warnings or notices) in CLI calls
on live environments.

It does this by adding a 2nd argument to our output handler,
CliFormatter. This formatter will be used when Director::is_cli() is
true.

_config/logging.yml

@@ -37,8 +37,9 @@ SilverStripe\Core\Injector\Injector:
     constructor:
       - "error"
     properties:
-      Formatter: %$FriendlyErrorFormatter
-  FriendlyErrorFormatter:
+      Formatter: %$SilverStripe\Logging\DebugViewFriendlyErrorFormatter
+      CLIFormatter: %$SilverStripe\Logging\DetailedErrorFormatter
+  SilverStripe\Logging\DebugViewFriendlyErrorFormatter:
     class: SilverStripe\Logging\DebugViewFriendlyErrorFormatter
     properties:
       Title: "There has been an error"

docs/en/02_Developer_Guides/07_Debugging/01_Error_Handling.md

@@ -107,7 +107,7 @@ To send emails, you can use Monolog's [NativeMailerHandler](https://github.com/S
 	        - error
 	      properties:
 	        ContentType: text/html
-	        Formatter: %$SilverStripe\Framework\Logging\DetailedErrorFormatter
+	        Formatter: %$SilverStripe\Logging\DetailedErrorFormatter
 
 The first section 4 lines passes a new handler to `Logger::pushHandler()` from the named service `MailHandler`. The
 next 10 lines define what the service is.
@@ -157,11 +157,12 @@ non-dev.
 	    calls:
 	      - [ pushHandler, [ %$DisplayErrorHandler ]] 
 	  DisplayErrorHandler:
-	    class: SilverStripe\Framework\Logging\HTTPOutputHandler
+	    class: SilverStripe\Logging\HTTPOutputHandler
 	    constructor:
 	      - "notice"
 	    properties:
-	      Formatter: %$SilverStripe\Framework\Logging\DetailedErrorFormatter
+	      Formatter: %$SilverStripe\Logging\DetailedErrorFormatter
+          CLIFormatter: %$SilverStripe\Logging\DetailedErrorFormatter
 	---
 	Name: live-errors
 	Except:
@@ -181,13 +182,13 @@ non-dev.
 	      Formatter: %$Monolog\Formatter\HtmlFormatter
 	      ContentType: text/html
 	  DisplayErrorHandler:
-	    class: SilverStripe\Framework\Logging\HTTPOutputHandler
+	    class: SilverStripe\Logging\HTTPOutputHandler
 	    constructor:
 	      - "error"
 	    properties:
-	      Formatter: %$FriendlyErrorFormatter
-	  FriendlyErrorFormatter:
-	    class: SilverStripe\Framework\Logging\DebugViewFriendlyErrorFormatter
+	      Formatter: %$SilverStripe\Logging\DebugViewFriendlyErrorFormatter
+	  SilverStripe\Logging\DebugViewFriendlyErrorFormatter:
+	    class: SilverStripe\Logging\DebugViewFriendlyErrorFormatter
 	    properties:
 	      Title: "There has been an error"
 	      Body: "The website server has not been able to respond to your request"
@@ -236,21 +237,21 @@ be ignored.
 
 ### Replacing the error handler
 
-The class `SilverStripe\Framework\Logging\MonologLoader` is responsible for loading performing Monolog-specific
-configuration. It does a number of things:
+The Injector service `ErrorHandler` is responsible for initialising the error handler. By default it 
 
- * Create a `Monolog\ErrorHandler` object.
- * Register the registered service `Logger` against it, to start the error handler.
- * If `Logger` has a `pushHandler()` method, pass every object defined by `ErrorHandler.handlers` into it, one at a time.
+ * Create a `SilverStripe\Logging\MonologErrorHandler` object.
+ * Attach the registered service `Psr\Log\LoggerInterface` to it, to start the error handler.
+ 
+Core.php will call `start()` on this method, to start the error handler.
 
 This error handler is flexible enough to work with any PSR-3 logging implementation, but sometimes you will want to use
 another. To replace this, you should registered a new service, `ErrorHandlerLoader`.  For example:
 
 	SilverStripe\Core\Injector\Injector:
-	  ErrorHandlerLoader: 
+	  ErrorHandler: 
 	    class: MyApp\CustomErrorHandlerLoader
 
-You should register something `Callable`, for example a class with an `__invoke()` method.
+You should register something with a `start()` method.
 
 ## Differences from SilverStripe 3
 

src/Logging/HTTPOutputHandler.php

@@ -3,8 +3,10 @@
 namespace SilverStripe\Logging;
 
 use SilverStripe\Control\Controller;
+use SilverStripe\Control\Director;
 use SilverStripe\Control\HTTPResponse;
 use Monolog\Handler\AbstractProcessingHandler;
+use Monolog\Formatter\FormatterInterface;
 
 /**
  * Output the error to the browser, with the given HTTP status code.
@@ -23,6 +25,11 @@ class HTTPOutputHandler extends AbstractProcessingHandler
      */
     private $statusCode = 500;
 
+    /**
+     * @var FormatterInterface
+     */
+    private $cliFormatter = null;
+
     /**
      * Get the mime type to use when displaying this error.
      *
@@ -38,7 +45,7 @@ class HTTPOutputHandler extends AbstractProcessingHandler
      * Default text/html
      *
      * @param string $contentType
-     * @return $this
+     * @return HTTPOutputHandler Return $this to allow chainable calls
      */
     public function setContentType($contentType)
     {
@@ -69,6 +76,45 @@ class HTTPOutputHandler extends AbstractProcessingHandler
         return $this;
     }
 
+    /**
+     * Set a formatter to use if Director::is_cli() is true
+     *
+     * @param $cliFormatter
+     * @return HTTPOutputHandler Return $this to allow chainable calls
+     */
+    public function setCLIFormatter(FormatterInterface $cliFormatter)
+    {
+        $this->cliFormatter = $cliFormatter;
+
+        return $this;
+    }
+
+    /**
+     * Return the formatter use if Director::is_cli() is true
+     * If none has been set, null is returned, and the getFormatter() result will be used instead
+     *
+     * @return FormatterInterface
+     */
+    public function getCLIFormatter()
+    {
+        return $this->cliFormatter;
+    }
+
+    /**
+     * Return the formatter to use in this case.
+     * May be the getCliFormatter() value if one is provided and Director::is_cli() is true.
+     *
+     * @return FormatterInterface
+     */
+    public function getFormatter()
+    {
+        if (Director::is_cli() && ($cliFormatter = $this->getCLIFormatter())) {
+            return $cliFormatter;
+        }
+
+        return parent::getFormatter();
+    }
+
     /**
      * @param array $record
      * @return bool