Terraform部署Lambda集成REST API：POST正常GET报500错误求助

问题 #

我用Terraform部署了一个包含GET和POST方法的AWS REST API，两个方法分别对接代码完全相同的Lambda函数（返回"Hello World"），但POST请求正常返回200，GET请求始终返回500错误：

• 当GET集成类型设为MOCK时：Execution failed due to configuration error: No match for output mapping and no default output mapping configured. Endpoint Response Status Code: 200
• 当GET集成类型设为AWS_PROXY时：Lambda invocation failed with status: 403. Lambda request id: 5b23639d-f6fb-4130-acf0-15db9a2f76b0

排查方向与解决方案 #

1. 修正GET集成的integration_http_method配置 #

在AWS_PROXY模式下，不管API对外暴露的HTTP方法是GET还是POST，API Gateway调用Lambda时的integration_http_method必须固定设为POST——这是AWS的硬性规则，和外部请求方法无关。你的POST集成配置正确，但GET集成错误地使用了GET，这是核心问题。

2. 移除GET集成中多余的request_templates #

AWS_PROXY模式下，API Gateway会自动将完整的请求上下文转发给Lambda，不需要手动配置请求模板。多余的模板会干扰正常的请求转发逻辑，直接删除即可。

3. 确认Lambda权限配置 #

即使你认为IAM权限正常，仍需确保API Gateway拥有调用GET对应Lambda的权限。可以通过Terraform的aws_lambda_permission资源明确授权：

resource "aws_lambda_permission" "api_gateway_get" {
  statement_id  = "AllowAPIGatewayInvokeGet"
  action        = "lambda:InvokeFunction"
  function_name = aws_lambda_function.lambda_hello_world_v1_get.function_name
  principal     = "apigateway.amazonaws.com"
  source_arn    = "${aws_api_gateway_rest_api.hello_world_v1.execution_arn}/*/GET/test"
}

4. 修正Deployment的依赖关系 #

当前Deployment仅依赖Method资源，应该同时依赖Integration资源，确保部署时集成配置已经完全生效：

resource "aws_api_gateway_deployment" "hello_world_v1" {
  rest_api_id = aws_api_gateway_rest_api.hello_world_v1.id
  depends_on = [
    aws_api_gateway_integration.hello_world_v1_get,
    aws_api_gateway_integration.hello_world_v1_post
  ]
}

修正后的Terraform核心配置 #

################################################################################
# REST API and Resource
################################################################################
resource "aws_api_gateway_rest_api" "hello_world_v1" {
  name = "hello_world_v1"
}

resource "aws_api_gateway_resource" "hello_world_v1" {
  parent_id   = aws_api_gateway_rest_api.hello_world_v1.root_resource_id
  rest_api_id = aws_api_gateway_rest_api.hello_world_v1.id
  path_part   = "test"
}

################################################################################
# GET - method and integration（已修正）
################################################################################
resource "aws_api_gateway_method" "hello_world_v1_get" {
  rest_api_id   = aws_api_gateway_rest_api.hello_world_v1.id
  resource_id   = aws_api_gateway_resource.hello_world_v1.id
  http_method   = "GET"
  authorization = "NONE"
}

resource "aws_api_gateway_integration" "hello_world_v1_get" {
  rest_api_id             = aws_api_gateway_rest_api.hello_world_v1.id
  resource_id             = aws_api_gateway_method.hello_world_v1_get.resource_id
  http_method             = aws_api_gateway_method.hello_world_v1_get.http_method
  integration_http_method = "POST" # 关键修正：必须设为POST
  type                    = "AWS_PROXY"
  uri                     = aws_lambda_function.lambda_hello_world_v1_get.invoke_arn
}

# 新增Lambda权限授权
resource "aws_lambda_permission" "api_gateway_get" {
  statement_id  = "AllowAPIGatewayInvokeGet"
  action        = "lambda:InvokeFunction"
  function_name = aws_lambda_function.lambda_hello_world_v1_get.function_name
  principal     = "apigateway.amazonaws.com"
  source_arn    = "${aws_api_gateway_rest_api.hello_world_v1.execution_arn}/*/GET/test"
}

################################################################################
# POST - method and integration（保持不变）
################################################################################
resource "aws_api_gateway_method" "hello_world_v1_post" {
  rest_api_id   = aws_api_gateway_rest_api.hello_world_v1.id
  resource_id   = aws_api_gateway_resource.hello_world_v1.id
  http_method   = "POST"
  authorization = "NONE"
}

resource "aws_api_gateway_integration" "hello_world_v1_post" {
  rest_api_id             = aws_api_gateway_rest_api.hello_world_v1.id
  resource_id             = aws_api_gateway_method.hello_world_v1_post.resource_id
  http_method             = aws_api_gateway_method.hello_world_v1_post.http_method
  integration_http_method = "POST"
  type                    = "AWS_PROXY"
  uri                     = aws_lambda_function.lambda_hello_world_v1_post.invoke_arn
}

# 新增POST对应的Lambda权限（如果之前未配置）
resource "aws_lambda_permission" "api_gateway_post" {
  statement_id  = "AllowAPIGatewayInvokePost"
  action        = "lambda:InvokeFunction"
  function_name = aws_lambda_function.lambda_hello_world_v1_post.function_name
  principal     = "apigateway.amazonaws.com"
  source_arn    = "${aws_api_gateway_rest_api.hello_world_v1.execution_arn}/*/POST/test"
}

################################################################################
# Stage and Deployment（修正依赖）
################################################################################
resource "aws_api_gateway_deployment" "hello_world_v1" {
  rest_api_id = aws_api_gateway_rest_api.hello_world_v1.id
  depends_on = [
    aws_api_gateway_integration.hello_world_v1_get,
    aws_api_gateway_integration.hello_world_v1_post
  ]
}

resource "aws_api_gateway_stage" "hello_world_v1" {
  deployment_id = aws_api_gateway_deployment.hello_world_v1.id
  rest_api_id   = aws_api_gateway_rest_api.hello_world_v1.id
  stage_name    = "development"
}

Lambda代码（保持不变） #

import json

def lambda_handler(event, context):
    return {
        "statusCode": 200,
        "headers": {
            "Content-Type": "application/json"
        },
        "body": json.dumps("Hello World")
    }

内容的提问来源于stack exchange，提问作者Srikar-231232