terraform with aws api gateway and aws lambda general flow of resources

Terraform is a bit unwieldy looking when working with API Gateway, this is due to the shear number of resources required to stand up a simple API Gateway that talks to a few lambdas.

The general flow of resources:

1. API Gateway itself
2. API Gateway Resource for each path portion
   1. Example: /test has a resource for test
   2. Example: /test/other has 2 resources for test and other, where other references test as a parent
3. API Gateway Method for each path portion that requires a method (GET/POST/etc.)
   1. Note: These are registered to the paths that have a method, not each resource
4. API Gateway Integration for each method that was created
5. API Gateway Deployment once all resources are created

Note: The below is an example, but utilizes some older Terraform versions for modules and whatnot. This is likely not the most up-to-date representation of the individual attributes, but the general workflow of resources is the same.

• Good StackOverflow reference

Example implementation

Below are stubbed examples of a barebones API Gateway deployment in Terraform. I'm creating a few paths and one that accepts an argument, then passes this to a registered AWS Lambda.

################
# API Gateway  #
################
resource "aws_api_gateway_rest_api" "example_rest_api" {
    name = "example-name"
    description = "example API Gateway"
}

################
# Path proxies #
################
# Path: test/
resource "aws_api_gateway_resource" "proxy_test" {
    rest_api_id = aws_api_gateway_rest_api.example_rest_api.id
    parent_id = aws_api_gateway_rest_api.example_rest_api.root_resource_id
    path_part = "test"
}

# Path: test/endpoint_one
resource "aws_api_gateway_resource" "proxy_endpoint_one" {
    rest_api_id = aws_api_gateway_rest_api.example_rest_api.id
    parent_id = aws_api_gateway_rest_api.proxy_test.id
    path_part = "endpoint_one"
}

# Path: test/endpoint_one/{userId}
resource "aws_api_gateway_resource" "proxy_userid" {
    rest_api_id = aws_api_gateway_rest_api.example_rest_api.id
    parent_id = aws_api_gateway_rest_api.proxy_endpoint_one.id
    path_part = "{userId}"
}

#######################
# Method registration #
#######################
# Path: test/endpoint_one/{userId}
resource "aws_api_gateway_method" "lambda_method_userid_endpoint" {
    rest_api_id = aws_api_gateway_rest_api.example_rest_api.id
    resource_id = aws_api_gateway_resource.proxy_endpoint_one.id
    http_method = "GET"
    authorization = "AWS_IAM"
}

#######################
# Integrate lambdas   #
#######################
resource "aws_api_gateway_integration" "lambda_userid_integration" {
    depends_on = [
        module.userid_lambda,
    ]
    rest_api_id = aws_api_gateway_rest_api.example_rest_api.id
    resource_id = aws_api_gateway_resource.proxy_userid.id

    # Required method for lambda
    integration_http_method = "POST"
    type = "AWS_PROXY"
    uri  = "arn:aws:apigateway:${local.region}:lambda:path/2015-03-31/functions/${module.userid_lambda.lambda_function_arn}/invocations"
}

############################
# API Gateway deployment   #
############################
resource "aws_api_gateway_deployment" "example_deployment" {
    depends_on = [
        module.userid_lambda,
    ]
    rest_api_id = aws_api_gateway_rest_api.example_rest_api.id
    stage_name  = local.env
}

###################
# Create lambdas  #
###################
module "userid_lambda" {
    # Something here to create a lambda!
}