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AWS API Gateway - Custom Domain (Console + Terraform | Route53 + Without Route53)

  • You can find the source code for this video in my GitHub Repo.

Intro

In this video, we're going to go over the following sections:

  • Create Custom Domain Using AWS Console (without Route53)
  • Create Custom Domain Using AWS Console (Route53)
  • Create Custom Domain Using Terraform (Route53)

You can find the timestamps in the video description.

Create Custom Domain Using Terraform (Route53)

In this video, we're going to set up a custom domain for the AWS API Gateway. In the first section, we will do it manually using AWS Console and a domain hosted outside of Route53. Then we will still use the AWS Console, but our domain will be managed by Route53. The workflow is very similar except for the type of DNS records you need to create. Finally, which is my default approach is to use Terraform to issue a certificate, create a custom domain, and set up API mapping.

terraform/0-provider.tf
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provider "aws" {
  region = "us-east-1"
}

terraform {
  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = "~> 4.22.0"
    }
    random = {
      source  = "hashicorp/random"
      version = "~> 3.3.0"
    }
    archive = {
      source  = "hashicorp/archive"
      version = "~> 2.2.0"
    }
  }

  required_version = "~> 1.0"
}

AWS API Gateway.

terraform/1-api-gateway.tf
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resource "aws_apigatewayv2_api" "main" {
  name          = "main"
  protocol_type = "HTTP"
}

resource "aws_apigatewayv2_stage" "staging" {
  name        = "staging"
  api_id      = aws_apigatewayv2_api.main.id
  auto_deploy = true
}

S3 bucket.

terraform/2-lambda-bucket.tf
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resource "random_pet" "lambda_bucket_name" {
  prefix = "lambda"
  length = 2
}

resource "aws_s3_bucket" "lambda_bucket" {
  bucket        = random_pet.lambda_bucket_name.id
  force_destroy = true
}

resource "aws_s3_bucket_public_access_block" "lambda_bucket" {
  bucket = aws_s3_bucket.lambda_bucket.id

  block_public_acls       = true
  block_public_policy     = true
  ignore_public_acls      = true
  restrict_public_buckets = true
}

AWS Lambda.

terraform/3-hello-lambda.tf
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resource "aws_iam_role" "hello_lambda_exec" {
  name = "hello-lambda"

  assume_role_policy = <<POLICY
{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Principal": {
        "Service": "lambda.amazonaws.com"
      },
      "Action": "sts:AssumeRole"
    }
  ]
}
POLICY
}

resource "aws_iam_role_policy_attachment" "hello_lambda_policy" {
  role       = aws_iam_role.hello_lambda_exec.name
  policy_arn = "arn:aws:iam::aws:policy/service-role/AWSLambdaBasicExecutionRole"
}

resource "aws_lambda_function" "hello" {
  function_name = "hello"

  s3_bucket = aws_s3_bucket.lambda_bucket.id
  s3_key    = aws_s3_object.lambda_hello.key

  runtime = "nodejs16.x"
  handler = "function.handler"

  source_code_hash = data.archive_file.lambda_hello.output_base64sha256

  role = aws_iam_role.hello_lambda_exec.arn
}

resource "aws_cloudwatch_log_group" "hello" {
  name = "/aws/lambda/${aws_lambda_function.hello.function_name}"

  retention_in_days = 14
}

data "archive_file" "lambda_hello" {
  type = "zip"

  source_dir  = "../${path.module}/hello"
  output_path = "../${path.module}/hello.zip"
}

resource "aws_s3_object" "lambda_hello" {
  bucket = aws_s3_bucket.lambda_bucket.id

  key    = "hello.zip"
  source = data.archive_file.lambda_hello.output_path

  etag = filemd5(data.archive_file.lambda_hello.output_path)
}

API Gateway Lambda integration.

terraform/4-hello-api-gateway.tf
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resource "aws_apigatewayv2_integration" "lambda_hello" {
  api_id = aws_apigatewayv2_api.main.id

  integration_uri    = aws_lambda_function.hello.invoke_arn
  integration_type   = "AWS_PROXY"
  integration_method = "POST"
}

resource "aws_apigatewayv2_route" "get_hello" {
  api_id = aws_apigatewayv2_api.main.id

  route_key = "GET /hello"
  target    = "integrations/${aws_apigatewayv2_integration.lambda_hello.id}"
}

resource "aws_lambda_permission" "api_gw" {
  statement_id  = "AllowExecutionFromAPIGateway"
  action        = "lambda:InvokeFunction"
  function_name = aws_lambda_function.hello.function_name
  principal     = "apigateway.amazonaws.com"

  source_arn = "${aws_apigatewayv2_api.main.execution_arn}/*/*"
}

output "hello_base_url" {
  value = "${aws_apigatewayv2_stage.staging.invoke_url}/hello"
}

To set up a custom domain with terraform, we still need to follow the same workflow. First, we need to issue a TLS certificate.

terraform/5-certificate.tf
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resource "aws_acm_certificate" "api" {
  domain_name       = "api.antonputra.com"
  validation_method = "DNS"
}

data "aws_route53_zone" "public" {
  name         = "antonputra.com"
  private_zone = false
}

resource "aws_route53_record" "api_validation" {
  for_each = {
    for dvo in aws_acm_certificate.api.domain_validation_options : dvo.domain_name => {
      name   = dvo.resource_record_name
      record = dvo.resource_record_value
      type   = dvo.resource_record_type
    }
  }

  allow_overwrite = true
  name            = each.value.name
  records         = [each.value.record]
  ttl             = 60
  type            = each.value.type
  zone_id         = data.aws_route53_zone.public.zone_id
}

resource "aws_acm_certificate_validation" "api" {
  certificate_arn         = aws_acm_certificate.api.arn
  validation_record_fqdns = [for record in aws_route53_record.api_validation : record.fqdn]
}

The next step is to create a custom domain using terraform. Specify the domain name, which should match the certificate.

terraform/6-custom-domain-name.tf
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resource "aws_apigatewayv2_domain_name" "api" {
  domain_name = "api.antonputra.com"

  domain_name_configuration {
    certificate_arn = aws_acm_certificate.api.arn
    endpoint_type   = "REGIONAL"
    security_policy = "TLS_1_2"
  }

  depends_on = [aws_acm_certificate_validation.api]
}

resource "aws_route53_record" "api" {
  name    = aws_apigatewayv2_domain_name.api.domain_name
  type    = "A"
  zone_id = data.aws_route53_zone.public.zone_id

  alias {
    name                   = aws_apigatewayv2_domain_name.api.domain_name_configuration[0].target_domain_name
    zone_id                = aws_apigatewayv2_domain_name.api.domain_name_configuration[0].hosted_zone_id
    evaluate_target_health = false
  }
}

In the last file, let's create API mapping. The first one is for the base path. And the second one is to map the staging stage with the v1 path.

terraform/7-api-mapping.tf
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resource "aws_apigatewayv2_api_mapping" "api" {
  api_id      = aws_apigatewayv2_api.main.id
  domain_name = aws_apigatewayv2_domain_name.api.id
  stage       = aws_apigatewayv2_stage.staging.id
}

resource "aws_apigatewayv2_api_mapping" "api_v1" {
  api_id          = aws_apigatewayv2_api.main.id
  domain_name     = aws_apigatewayv2_domain_name.api.id
  stage           = aws_apigatewayv2_stage.staging.id
  api_mapping_key = "v1"
}

output "custom_domain_api" {
  value = "https://${aws_apigatewayv2_api_mapping.api.domain_name}"
}

output "custom_domain_api_v1" {
  value = "https://${aws_apigatewayv2_api_mapping.api_v1.domain_name}/${aws_apigatewayv2_api_mapping.api_v1.api_mapping_key}"
}

Run terraform.

terraform init
terraform apply

Test with curl.

curl https://api.antonputra.com/hello
curl https://api.antonputra.com/v1/hello
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