这是因为所有的HTTP API在默认情况下只在$default 阶段处于激活状态。所以，如果您要在其他阶段和自定义域上使用API，则需要在每个阶段为API添加路由，以便API可以在这些阶段和自定义域上工作。

以下是将HTTP API设置为可在任何阶段使用的示例代码：

resource "aws_apigatewayv2_api" "example_api" {
  name          = "example-api"
  protocol_type = "HTTP"
}

resource "aws_apigatewayv2_stage" "staging" {
  api_id          = aws_apigatewayv2_api.example_api.id
  name            = "staging"
  auto_deploy     = true
  default_route_settings {
    detailed_metrics_enabled = true
  }
}

resource "aws_apigatewayv2_stage" "production" {
  api_id          = aws_apigatewayv2_api.example_api.id
  name            = "production"
  auto_deploy     = true
  default_route_settings {
    detailed_metrics_enabled = true
  }
}

resource "aws_apigatewayv2_api_mapping" "staging_mapping" {
  api_id      = aws_apigatewayv2_api.example_api.id
  domain_name = var.staging_domain_name
  stage       = aws_apigatewayv2_stage.staging.name
}

resource "aws_apigatewayv2_api_mapping" "production_mapping" {
  api_id      = aws_apigatewayv2_api.example_api.id
  domain_name = var.production_domain_name
  stage       = aws_apigatewayv2_stage.production.name
}

resource "aws_apigatewayv2_route" "example_route" {
  api_id    = aws_apigatewayv2_api.example_api.id
  route_key = "GET /example"
  target    = "integrations/${aws_apigatewayv2_integration.example_integration.id}"
}

resource "aws_apigatewayv2_integration" "example_integration" {
  api_id             = aws_apigatewayv2_api.example_api.id
  integration_type   = "HTTP_PROXY"
  integration_uri    = var.example_integration_uri
  passthrough_behavior = "WHEN_NO_MATCH"
}

在这个示例中，我们在每个阶段创建一个路由，然后将这些路由的集成指向我们的后端URI。最后，为每个阶段创建了一个API映射来将自定义域名与API和阶段相关联。这样