Top 10 Solutions for AWS API Gateway Rest API Management

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Introduction

This article aims to provide a step-by-step guide on how to create and manage a REST API Gateway in AWS using Terraform. The REST API Gateway is a key component in building scalable and reliable APIs. However, navigating through the documentation can be time-consuming and overwhelming, especially for beginners.

To address this issue, this article will summarize the research and provide assistance to readers in creating a REST API Gateway with Terraform. Each step will be explained in detail, and actual working sample codes will be provided for a better understanding of the process.

1. Base API Gateway REST API

The first step in creating a REST API Gateway is to define the base REST API. With Terraform, this can be done easily using a resource block. Within this resource block, you can include optional elements such as description and body, which is the OpenAPI Specification for your API. Additionally, you can also configure the endpoints for your REST API.

resource "aws_api_gateway_rest_api" "my_rest_api" {
  name        = "my-api"
  description = "This is my REST API"
  body        = file("${path.module}/openapi-spec.yml")

  endpoint_configuration {
    types = ["EDGE"]
  }
}

In the example above, we define a REST API named “my-api” with a description. We also specify the OpenAPI Specification for our API by referencing a YAML file using the file function. Lastly, we configure the endpoint type as "EDGE", which allows the API to use the AWS global network for low-latency access.

2. Ingress Policy API Gateway REST API Policy

Managing ingress access to the API Gateway is crucial for security purposes. With the help of the aws_api_gateway_rest_api_policy resource block, you can define an ingress policy that restricts access to specific IP ranges.

resource "aws_api_gateway_rest_api_policy" "my_rest_api_policy" {
  rest_api_id = aws_api_gateway_rest_api.my_rest_api.id
  policy      = <<EOF
{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Principal": "*",
      "Action": "execute-api:Invoke",
      "Resource": "execute-api:/*",
      "Condition": {
        "IpAddress": {
          "aws:SourceIp": ["10.0.0.0/8", "192.168.0.0/16"]
        }
      }
    }
  ]
}
EOF
}

In the sample code above, an ingress policy is defined using the aws_api_gateway_rest_api_policy resource. The policy allows the execute-api:Invoke action for all principals but restricts access to IP ranges 10.0.0.0/8 and 192.168.0.0/16.

3. Define the Exposed Resources

In order to define the exposed resources for your REST API, you can use the aws_api_gateway_resource resource block. This step is crucial for properly structuring your API endpoints.

resource "aws_api_gateway_resource" "users_resource" {
  rest_api_id = aws_api_gateway_rest_api.my_rest_api.id
  parent_id   = aws_api_gateway_rest_api.my_rest_api.root_resource_id
  path_part   = "users"
}

resource "aws_api_gateway_resource" "cards_resource" {
  rest_api_id = aws_api_gateway_rest_api.my_rest_api.id
  parent_id   = aws_api_gateway_resource.users_resource.id
  path_part   = "cards"
}

In the above example, we define two resources, /users and /cards, using the aws_api_gateway_resource resource block. The parent_id parameter specifies the parent resource, and the path_part parameter defines the path of the resource.

4. Declare Methods API Gateway Method

Next, we need to declare the methods for each path using the aws_api_gateway_method resource block. This step is crucial for defining the desired functionality for each API endpoint.

resource "aws_api_gateway_method" "get_cards" {
  rest_api_id   = aws_api_gateway_rest_api.my_rest_api.id
  resource_id   = aws_api_gateway_resource.cards_resource.id
  http_method   = "GET"
  authorization = "NONE"
}

In the above code snippet, we declare a GET method for the /cards resource using the aws_api_gateway_method resource block. We set the http_method parameter to "GET" and the authorization parameter to "NONE" to allow unauthenticated access to this endpoint.

5. Integrate Endpoints API Gateway Integration

To integrate endpoints with different services, we can use the aws_api_gateway_integration resource block. This allows us to specify how the API Gateway should interact with the backend services.

resource "aws_api_gateway_integration" "lambda_integration" {
  rest_api_id             = aws_api_gateway_rest_api.my_rest_api.id
  resource_id             = aws_api_gateway_resource.cards_resource.id
  http_method             = aws_api_gateway_method.get_cards.http_method
  integration_http_method = "POST"
  type                    = "AWS_PROXY"
  uri                     = aws_lambda_function.my_lambda_api.invoke_arn
}

In the code above, we integrate the /cards endpoint with a Lambda function using the aws_api_gateway_integration resource block. We specify the HTTP method, integration HTTP method, type (in this case, "AWS_PROXY" for invoking a Lambda function), and the URI of the Lambda function.

6. Declare Mock HTTP Response API Gateway Method Response

The aws_api_gateway_method_response resource block helps us declare the mock HTTP response for a method. This allows us to define the structure of the response that the API Gateway will return.

resource "aws_api_gateway_method_response" "success_response" {
  rest_api_id = aws_api_gateway_rest_api.my_rest_api.id
  resource_id = aws_api_gateway_resource.cards_resource.id
  http_method = aws_api_gateway_method.get_cards.http_method
  status_code = "200"

  response_models = {
    "application/json" = "Empty"
  }
}

In the above example, we define a method response with a status code of 200 for the GET method of the /cards resource. We also specify the response model as "Empty" for the "application/json" content type.

7. Declare Mock HTTP Response Body API Gateway Integration Response

To declare the mock HTTP response body for an integration response, we can use the aws_api_gateway_integration_response resource block. This allows us to transform and define the response structure.

resource "aws_api_gateway_integration_response" "transform_response" {
  rest_api_id          = aws_api_gateway_rest_api.my_rest_api.id
  resource_id          = aws_api_gateway_resource.cards_resource.id
  http_method          = aws_api_gateway_method.get_cards.http_method
  status_code          = aws_api_gateway_method_response.success_response.status_code
  response_templates   = {
    "text/xml" = <<EOF
<TransformResponse xmlns="http://example.com/transform">
  <Result>$input.path('$.result')</Result>
</TransformResponse>
EOF
  }
}

In the code snippet above, we define an integration response that transforms the backend JSON response into XML. The response template contains XML tags that wrap around the transformed response.

Conclusion

In conclusion, creating and managing a REST API Gateway in AWS with Terraform can be simplified by following a step-by-step guide. This article has covered the primary steps involved in this process, including declaring the base REST API, managing ingress policies, defining exposed resources, declaring methods, integrating endpoints, and defining mock HTTP responses.

By following the provided sample codes and explanations, readers should be able to create their own REST API Gateway in AWS with Terraform more easily. Remember to refer to the Terraform documentation and AWS documentation for further details and configuration options. Happy coding!

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