Added possibility to set max length for level name in LineFormatter

Closes #1850

src/Monolog/Formatter/LineFormatter.php

@@ -31,6 +31,7 @@ class LineFormatter extends NormalizerFormatter
     protected bool $allowInlineLineBreaks;
     protected bool $ignoreEmptyContextAndExtra;
     protected bool $includeStacktraces;
+    protected ?int $maxLevelNameLength = null;
     protected Closure|null $stacktracesParser = null;
 
     /**
@@ -83,6 +84,19 @@ class LineFormatter extends NormalizerFormatter
         return $this;
     }
 
+    /**
+     * Allows cutting the level name to get fixed-length levels like INF for INFO, ERR for ERROR if you set this to 3 for example
+     *
+     * @param int|null $maxLevelNameLength Maximum characters for the level name. Set null for infinite length (default)
+     * @return $this
+     */
+    public function setMaxLevelNameLength(?int $maxLevelNameLength = null): self
+    {
+        $this->maxLevelNameLength = $maxLevelNameLength;
+
+        return $this;
+    }
+
     /**
      * @inheritDoc
      */
@@ -90,6 +104,10 @@ class LineFormatter extends NormalizerFormatter
     {
         $vars = parent::format($record);
 
+        if ($this->maxLevelNameLength !== null) {
+            $vars['level_name'] = substr($vars['level_name'], 0, $this->maxLevelNameLength);
+        }
+
         $output = $this->format;
         foreach ($vars['extra'] as $var => $val) {
             if (false !== strpos($output, '%extra.'.$var.'%')) {

tests/Monolog/Formatter/LineFormatterTest.php

@@ -276,6 +276,40 @@ class LineFormatterTest extends TestCase
 
         $this->assertMatchesRegularExpression('/foo\nbar/', $message);
     }
+
+    /**
+     * @dataProvider providerMaxLevelNameLength
+     */
+    public function testMaxLevelNameLength(?int $maxLength, Level $logLevel, string $expectedLevelName): void
+    {
+        $formatter = new LineFormatter(maxLevelNameLength: $maxLength);
+        $message = $formatter->format($this->getRecord(message: "foo\nbar", level: $logLevel));
+
+        $this->assertStringContainsString("test.$expectedLevelName:", $message);
+    }
+
+    public static function providerMaxLevelNameLength(): array
+    {
+        return [
+            'info_no_max_length' => [
+                'max_length' => null,
+                'level' => Level::Info,
+                'expected_level_name' => 'INFO',
+            ],
+
+            'error_max_length_3' => [
+                'max_length' => 3,
+                'level' => Level::Error,
+                'expected_level_name' => 'ERR',
+            ],
+
+            'debug_max_length_2' => [
+                'max_length' => 2,
+                'level' => Level::Debug,
+                'expected_level_name' => 'DE',
+            ],
+        ];
+    }
 }
 
 class TestFoo