main.tf

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# aws_s3_bucket_versioning, version update is needed to trigger cloudfront cache invalidation
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resource "aws_s3_bucket_versioning" "static_site_versioning" {
  bucket = aws_s3_bucket.static_site.id
  versioning_configuration {
    status = "Enabled"
  }
}

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# aws_s3_object, upload site to bucket
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resource "aws_s3_object" "static_site" {
  # Must have bucket versioning enabled first
  depends_on = [aws_s3_bucket_versioning.static_site_versioning]

  bucket       = aws_s3_bucket.static_site.id
  key          = "index.html"
  acl          = aws_s3_bucket_acl.static_site
  source       = "./build/index.html" 
  etag         = filemd5("./build/index.html")
  content_type = "text/html"
}

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# null_resource, invalidate CF cache when S3 website home page is updated, use path /* to invalidate whole site to save cost
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resource "null_resource" "invalidate_cf_cache" {
  provisioner "local-exec" {
    command = "aws cloudfront create-invalidation --distribution-id ${aws_cloudfront_distribution.static_site.id} --paths '/*'"
  }
  triggers = {
    website_version_changed = aws_s3_object.static_site.version_id
  }
}