fix: clear cached path on ECS token file

.changes/nextrelease/fix-clear-cached-path-ecs.json

@@ -0,0 +1,7 @@
+[
+  {
+    "type": "bugfix",
+    "category": "Credentials",
+    "description": "Clears cached path for authorization token when necessary on ECS credentials provider."
+  }
+]

src/Credentials/EcsCredentialProvider.php

@@ -97,13 +97,24 @@ public function __invoke()
     private function getEcsAuthToken()
     {
         if (!empty($path = getenv(self::ENV_AUTH_TOKEN_FILE))) {
-            if (is_readable($path)) {
-                return file_get_contents($path);
+            $token =  @file_get_contents($path);
+            if (false === $token) {
+                clearstatcache(true, dirname($path) . DIRECTORY_SEPARATOR . @readlink($path));
+                clearstatcache(true, dirname($path) . DIRECTORY_SEPARATOR . dirname(@readlink($path)));
+                clearstatcache(true, $path);
             }
 
-            throw new CredentialsException(
-                "Failed to read authorization token from '{$path}': no such file or directory."
-            );
+            if (!is_readable($path)) {
+                throw new CredentialsException("Failed to read authorization token from '{$path}': no such file or directory.");
+            }
+
+            $token = @file_get_contents($path);
+
+            if (empty($token)) {
+                throw new CredentialsException("Invalid authorization token read from `$path`. Token file is empty!");
+            }
+
+            return $token;
         }
 
         return getenv(self::ENV_AUTH_TOKEN);