如果在使用 AWS App Runner 时出现“Error in assuming instance role”错误，可能是由于实例角色的权限不足导致的。为解决此问题，您可以通过以下方法修改实例角色的策略：

1. 登录到 AWS 控制台并转到 IAM 服务
2. 找到实例角色并单击它，然后单击“添加权限”按钮
3. 选择“JSON”选项卡，然后将以下策略粘贴到 JSON 编辑器中：

{ "Version": "2012-10-17", "Statement": [ { "Sid": "AppRunnerAccess", "Effect": "Allow", "Action": [ "apprunner:CreateService", "apprunner:DescribeService", "apprunner:ListServices", "apprunner:DeleteService", "apprunner:UpdateService", "apprunner:CreateConnection", "apprunner:DescribeConnection", "apprunner:ListConnections", "apprunner:DeleteConnection", "apprunner:UpdateConnection", "apprunner:AssociateCustomDomain", "apprunner:DisassociateCustomDomain" ], "Resource": "*" } ] }

4. 单击“验证策略”按钮，然后单击“添加权限”按钮以保存更改。 您的实例角色现在应该具有足够的权限来假定角色并在 AWS App Runner 上运行应用程序。