🐶
Terraform

Terraform: Upload Files to S3 on Every Apply

By Filip on 11/10/2024

Learn how to automatically upload files to AWS S3 buckets on every Terraform apply using practical examples and best practices.

Terraform: Upload Files to S3 on Every Apply

Table of Contents

Introduction

This guide provides practical examples of how to upload files to an AWS S3 bucket using Terraform. We'll cover various scenarios, including uploading single files, multiple files, setting content types, forcing file re-uploads, and strategies for uploading entire folders.

Step-by-Step Guide

  1. Upload a single file:

    resource "aws_s3_bucket_object" "example" {
  bucket = "your-bucket-name"
  key    = "example.txt"
  source = "example.txt" 
}

    Replace "your-bucket-name" with your S3 bucket name, "example.txt" with your desired object key, and "example.txt" with the path to your local file.

  2. Upload multiple files: You can use a loop in Terraform to upload multiple files. Here's an example using for_each:

    resource "aws_s3_bucket_object" "example" {
  for_each = fileset("path/to/files", "*")
  bucket = "your-bucket-name"
  key    = each.value
  source = "path/to/files/${each.value}"
}

    This code iterates over each file in the "path/to/files" directory and creates an S3 object for each.

  3. Set content type: You can set the content_type attribute to specify the MIME type of the uploaded file:

    resource "aws_s3_bucket_object" "example" {
  # ... other attributes ...
  content_type = "text/plain" 
}

    Replace "text/plain" with the appropriate MIME type for your file.

  4. Force file re-upload: To force Terraform to re-upload a file on every apply, you can use the etag attribute. By setting it to md5(file("example.txt")), Terraform will calculate the file's MD5 hash and re-upload it if the hash changes:

    resource "aws_s3_bucket_object" "example" {
  # ... other attributes ...
  etag = filemd5("example.txt")
}

  5. Upload a whole folder: Terraform doesn't natively support uploading entire folders. You can use external tools or scripts to achieve this. One approach is to zip the folder and upload the zip file as a single object.

Remember to replace the example values with your actual bucket name, file paths, and desired configurations.

Code Example

This code provides examples of how to upload files to an AWS S3 bucket using Terraform. It covers uploading a single file, multiple files using a for_each loop, setting the content type, forcing file re-uploads with ETags, and uploading an entire folder using an external bash script and a null_resource. Remember to replace placeholder values with your actual bucket name, file paths, and ensure your AWS credentials are configured.

1. Upload a single file:

resource "aws_s3_bucket_object" "example_file" {
  bucket = "your-bucket-name"
  key    = "example.txt"
  source = "path/to/your/example.txt" 
}

2. Upload multiple files:

resource "aws_s3_bucket_object" "multiple_files" {
  for_each = fileset("path/to/files", "*")
  bucket = "your-bucket-name"
  key    = each.value
  source = "path/to/files/${each.value}"
}

3. Set content type:

resource "aws_s3_bucket_object" "example_file" {
  bucket = "your-bucket-name"
  key    = "example.txt"
  source = "path/to/your/example.txt" 
  content_type = "text/plain" 
}

4. Force file re-upload:

resource "aws_s3_bucket_object" "example_file" {
  bucket = "your-bucket-name"
  key    = "example.txt"
  source = "path/to/your/example.txt" 
  etag = filemd5("path/to/your/example.txt")
}

5. Upload a whole folder (using external script):

a) Create a bash script (upload_folder.sh):

#!/bin/bash

# Replace with your bucket name and folder path
BUCKET_NAME="your-bucket-name"
FOLDER_PATH="path/to/your/folder"

# Create a zip file of the folder
zip -r folder.zip "$FOLDER_PATH"

# Upload the zip file to S3
aws s3 cp folder.zip s3://$BUCKET_NAME/folder.zip

# Remove the local zip file
rm folder.zip

b) Make the script executable:

chmod +x upload_folder.sh

c) Execute the script within a null_resource in your Terraform code:

resource "null_resource" "upload_folder" {
  provisioner "local-exec" {
    command = "./upload_folder.sh"
  }
}

Remember:

  • Replace "your-bucket-name" with your actual S3 bucket name.
  • Replace "path/to/your/example.txt" and "path/to/files" with your actual file and folder paths.
  • Ensure you have the AWS CLI configured and necessary permissions to upload files to your S3 bucket.

Additional Notes

  • Bucket Existence: The provided code assumes the S3 bucket ("your-bucket-name") already exists. If not, you'll need to create it first using the aws_s3_bucket resource in your Terraform configuration.

  • File Paths: Double-check all file paths used in the source and filemd5 functions are correct relative to where you run Terraform.

  • Content Type Importance: Setting the correct content_type is crucial for files intended to be served directly from S3 (e.g., website assets). It ensures browsers interpret and display them correctly.

  • ETag for Cache Control: While using filemd5 to force re-uploads is useful for development, be mindful of its implications in production. Changing the ETag on every upload might prevent caching mechanisms from working effectively.

  • Alternative to External Scripts: Instead of using an external bash script for folder uploads, consider using a dedicated archiving tool within your workflow to create a zip file. Terraform can then upload this zip file.

  • State File Management: When working with Terraform, always store your state file securely and consider using remote backends (e.g., S3, Consul) for collaboration and state consistency.

  • Terraform Best Practices: Adhere to Terraform best practices, such as using modules for code reusability, input validation, and proper resource naming conventions.

  • Security Considerations: When uploading files to S3, be mindful of security implications. Set appropriate bucket policies and IAM permissions to control access to your objects.

Summary

This document summarizes how to upload files to an AWS S3 bucket using Terraform.

Key Points:

  • Single File Upload: Use the aws_s3_bucket_object resource to upload a single file. Specify the bucket name, object key, and local file path.
  • Multiple File Upload: Utilize the for_each meta-argument to iterate over a set of files and upload them individually.
  • Content Type: Set the content_type attribute to specify the MIME type of the uploaded file.
  • Force Re-upload: Use the etag attribute and set it to the file's MD5 hash to force Terraform to re-upload the file if its content changes.
  • Folder Upload: Terraform doesn't directly support uploading entire folders. Consider zipping the folder and uploading the archive as a single object.

Important Notes:

  • Remember to replace example values with your actual bucket name, file paths, and desired configurations.
  • For uploading entire folders, explore external tools or scripts to automate the process.

Conclusion

By following these examples and guidelines, you can effectively manage the upload of your files to AWS S3 buckets using Terraform, ensuring a streamlined and automated deployment process for your applications and data. Remember to consult the official Terraform documentation for the most up-to-date information and detailed explanations of the resources and functionalities used.

References

Were You Able to Follow the Instructions?

😍Love it!
😊Yes
😐Meh-gical
😞No
🤮Clickbait

Related posts

Terraform Output to File: Save and Share Results

Learn how to streamline your Terraform workflow by saving the output of your infrastructure deployments to a file for easy access and automation.

Terraform Apply Timeout Configuration Guide

Learn how to set a timeout for your Terraform apply commands to prevent runaway processes and ensure predictable infrastructure deployments.

Cloud Agnostic Terraform: A Complete Guide

Learn how to write reusable, cloud-agnostic Terraform code to seamlessly manage your infrastructure across different cloud providers.