[8.x] Add method for on-demand log creation

src/Illuminate/Log/LogManager.php

@@ -110,12 +110,13 @@ public function getChannels()
      * Attempt to get the log from the local cache.
      *
      * @param  string  $name
+     * @param  array|null  $config
      * @return \Psr\Log\LoggerInterface
      */
-    protected function get($name)
+    protected function get($name, ?array $config = null)
     {
         try {
-            return $this->channels[$name] ?? with($this->resolve($name), function ($logger) use ($name) {
+            return $this->channels[$name] ?? with($this->resolve($name, $config), function ($logger) use ($name) {
                 return $this->channels[$name] = $this->tap($name, new Logger($logger, $this->app['events']));
             });
         } catch (Throwable $e) {
@@ -180,13 +181,14 @@ protected function createEmergencyLogger()
      * Resolve the given log instance by name.
      *
      * @param  string  $name
+     * @param  array|null  $config
      * @return \Psr\Log\LoggerInterface
      *
      * @throws \InvalidArgumentException
      */
-    protected function resolve($name)
+    protected function resolve($name, ?array $config = null)
     {
-        $config = $this->configurationFor($name);
+        $config = $config ?? $this->configurationFor($name);
 
         if (is_null($config)) {
             throw new InvalidArgumentException("Log [{$name}] is not defined.");
@@ -242,11 +244,15 @@ protected function createStackDriver(array $config)
         }
 
         $handlers = collect($config['channels'])->flatMap(function ($channel) {
-            return $this->channel($channel)->getHandlers();
+            return $channel instanceof LoggerInterface
+                ? $channel->getHandlers()
+                : $this->channel($channel)->getHandlers();
         })->all();
 
         $processors = collect($config['channels'])->flatMap(function ($channel) {
-            return $this->channel($channel)->getProcessors();
+            return $channel instanceof LoggerInterface
+                ? $channel->getProcessors()
+                : $this->channel($channel)->getProcessors();
         })->all();
 
         if ($config['ignore_exceptions'] ?? false) {
@@ -630,6 +636,17 @@ public function log($level, $message, array $context = [])
         $this->driver()->log($level, $message, $context);
     }
 
+    /**
+     * Build an on-demand channel.
+     *
+     * @param  array  $config
+     * @return \Psr\Log\LoggerInterface
+     */
+    public function build(array $config)
+    {
+        return $this->get('ondemand', $config);
+    }
+
     /**
      * Dynamically call the default driver instance.
      *

tests/Log/LogManagerTest.php

@@ -13,6 +13,7 @@
 use Monolog\Handler\StreamHandler;
 use Monolog\Handler\SyslogHandler;
 use Monolog\Logger as Monolog;
+use Monolog\Processor\UidProcessor;
 use Orchestra\Testbench\TestCase;
 use ReflectionProperty;
 use RuntimeException;
@@ -377,4 +378,58 @@ public function testLogManagerPurgeResolvedChannels()
 
         $this->assertEmpty($manager->getChannels());
     }
+
+    public function testLogManagerCanBuildOnDemandChannel()
+    {
+        $manager = new LogManager($this->app);
+
+        $logger = $manager->build([
+            'driver' => 'single',
+            'path' => storage_path('logs/on-demand.log'),
+        ]);
+        $handler = $logger->getLogger()->getHandlers()[0];
+
+        $this->assertInstanceOf(StreamHandler::class, $handler);
+
+        $url = new ReflectionProperty(get_class($handler), 'url');
+        $url->setAccessible(true);
+
+        $this->assertSame(storage_path('logs/on-demand.log'), $url->getValue($handler));
+    }
+
+    public function testLogManagerCanUseOnDemandChannelInOnDemandStack()
+    {
+        $manager = new LogManager($this->app);
+        $this->app['config']->set('logging.channels.test', [
+            'driver' => 'single',
+        ]);
+
+        $factory = new class()
+        {
+            public function __invoke()
+            {
+                return new Monolog(
+                    'uuid',
+                    [new StreamHandler(storage_path('logs/custom.log'))],
+                    [new UidProcessor()]
+                );
+            }
+        };
+        $channel = $manager->build([
+            'driver' => 'custom',
+            'via' => get_class($factory),
+        ]);
+        $logger = $manager->stack(['test', $channel]);
+
+        $handler = $logger->getLogger()->getHandlers()[1];
+        $processor = $logger->getLogger()->getProcessors()[0];
+
+        $this->assertInstanceOf(StreamHandler::class, $handler);
+        $this->assertInstanceOf(UidProcessor::class, $processor);
+
+        $url = new ReflectionProperty(get_class($handler), 'url');
+        $url->setAccessible(true);
+
+        $this->assertSame(storage_path('logs/custom.log'), $url->getValue($handler));
+    }
 }