CloudFront on AWS: Basics & Setup Guide

Some websites load in a snap, while others make you wonder if the internet is broken. The difference? Often, it comes down to how (and where) their content is served.

A Content Delivery Network (CDN) helps by storing copies of your content in multiple locations worldwide, so users don’t have to wait for a distant server to respond. If you're on AWS, CloudFront is the built-in way to do this—helping speed things up while also handling security and traffic optimization.

In this guide, we’ll break down what a CDN does, why it matters, and how you can set up CloudFront to make your applications faster and more reliable. Let’s get started.

What's a CDN and Why Should You Care?

A Content Delivery Network (CDN) is a group of servers spread across different locations worldwide. When someone visits your site, the CDN delivers your content from the server closest to them. Simple, right?

But why does this matter? Two big reasons:

1. Speed: Your users get content from nearby servers, not from halfway across the world
2. Cost: Less strain on your origin server means lower hosting costs

For AWS users, CloudFront is the go-to CDN service that takes these benefits and cranks them up to eleven.

How CloudFront Improves Performance

CloudFront works by caching your content across a massive network of edge locations – over 310 points of presence (PoPs) across 90+ cities in 47 countries. That's a lot of servers ready to deliver your content!

When someone visits your site, here's what happens:

1. The request hits the nearest CloudFront edge location
2. If the content is cached there (a "cache hit"), it's delivered immediately
3. If not (a "cache miss"), CloudFront gets it from your origin server, delivers it, and caches it for future requests

This process typically cuts load times by 30-60% compared to direct origin delivery.

For example, imagine you're running an e-commerce site during a flash sale. Without CloudFront, your origin server might buckle under the traffic. With CloudFront, those product images, videos, and page elements get served from edge locations, keeping your site snappy even with thousands of concurrent users.

Performance Stats That'll Make You Smile

How CloudFront Saves You Cash

Let's talk numbers. While adding another service might seem like it would increase costs, CloudFront often leads to overall savings. Here's how:

Reduced Origin Costs

Your origin servers (whether EC2, S3, or something else) handle fewer requests, which means:

• Lower compute costs for EC2 instances
• Fewer GET requests for S3 buckets
• Less data transfer out from your origin

Bandwidth Savings

CloudFront's data transfer rates are often cheaper than direct data transfer from EC2 or S3 to the internet. Plus, there's no charge for data transfer from your AWS origin to CloudFront.

Real Cost Comparison

That's nearly $1,100 in annual savings, just on the CDN itself – not counting the reduced origin costs and potential revenue increases from better performance!

Setting Up CloudFront: A Step-by-Step Guide

Ready to get CloudFront running? Here's how to set it up in under 30 minutes:

Step 1: Prep Your Origin

First, make sure your content is ready. The most common origins are:

• S3 Bucket: Perfect for static content
• EC2 Instance or Load Balancer: Ideal for dynamic content
• Custom Origin: For non-AWS hosted content

For this guide, let's use an S3 bucket as our origin. Make sure your bucket has the right permissions:

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Sid": "AllowCloudFrontServicePrincipal",
            "Effect": "Allow",
            "Principal": {
                "Service": "cloudfront.amazonaws.com"
            },
            "Action": "s3:GetObject",
            "Resource": "arn:aws:s3:::your-bucket-name/*",
            "Condition": {
                "StringEquals": {
                    "AWS:SourceArn": "arn:aws:cloudfront::account-id:distribution/distribution-id"
                }
            }
        }
    ]
}

Step 2: Create Your CloudFront Distribution

1. Head to the AWS Management Console
2. Navigate to CloudFront
3. Click "Create Distribution"
4. For the origin domain, select your S3 bucket or enter your custom origin
5. Choose your cache behavior settings:
   • Protocol Policy: HTTP and HTTPS (or redirect HTTP to HTTPS)
   • Cache Policy: Use CachingOptimized for static content
   • Origin Request Policy: CORS-S3Origin works well for most cases

Step 3: Configure Cache Settings

This is where you can fine-tune performance. For optimal results:

• Set appropriate TTLs (Time To Live) based on how often your content changes
• Consider what URLs to cache (query strings, cookies, headers)
• Decide on compression settings

For a typical website with static assets, try these settings:

• Minimum TTL: 0 seconds
• Default TTL: 86400 seconds (1 day)
• Maximum TTL: 31536000 seconds (1 year)
• Query String Forwarding: None (unless needed)
• Cookie Forwarding: None (for static content)
• Compress Objects Automatically: Yes

Step 4: Set Up Custom Domains and SSL

Nobody wants to use those ugly default CloudFront URLs. Set up your domain:

1. Add your custom domain name in the distribution settings
2. Request or import an SSL certificate using AWS Certificate Manager (it's free!)
3. Set the SSL certificate in your CloudFront distribution
4. Update your DNS records to point to your CloudFront distribution

Step 5: Wait for Deployment and Test

After hitting "Create Distribution," you'll need to wait a bit – typically 5-10 minutes for the distribution to deploy. Once it's ready:

1. Try accessing your content through the CloudFront URL
2. Check that caching works by making multiple requests
3. Verify SSL is working correctly if you set up a custom domain

Advanced CloudFront Tricks For You to Try

If you've got the basics down, here are some power-user moves to take your CDN game to the next level:

Origin Groups for Failover

Set up multiple origins with automatic failover:

1. Create an origin group in your distribution
2. Add your primary and secondary origins
3. Configure failover criteria (like specific HTTP error codes)

This gives you high availability without complex code changes.

Lambda@Edge for Dynamic Content

Need to customize content on the fly? Lambda@Edge lets you run code at CloudFront edge locations to:

• Rewrite URLs
• Add/modify headers
• Personalize content
• Implement A/B testing

Here's a simple example that adds security headers to every response:

exports.handler = (event, context, callback) => {
    const response = event.Records[0].cf.response;
    const headers = response.headers;
    
    headers['strict-transport-security'] = [{
        key: 'Strict-Transport-Security',
        value: 'max-age=31536000; includeSubDomains; preload'
    }];
    
    headers['x-content-type-options'] = [{
        key: 'X-Content-Type-Options',
        value: 'nosniff'
    }];
    
    callback(null, response);
};

CloudFront Functions for Light Processing

For simpler use cases, CloudFront Functions are more cost-effective than Lambda@Edge and run even closer to your users:

function handler(event) {
    var request = event.request;
    var uri = request.uri;
    
    // Normalize URLs that end without an extension to add index.html
    if (uri.endsWith('/')) {
        request.uri = uri + 'index.html';
    }
    
    return request;
}

Monitoring and Optimizing Your CloudFront Setup

Once you're up and running, keep an eye on these metrics:

Key Performance Indicators

• Cache Hit Ratio: Aim for >85%
• Error Rates: Should be <1%
• Origin Latency: Monitor for spikes

AWS provides these metrics in CloudWatch. Create a dashboard with these metrics to spot issues quickly.

Cost Optimization Tips

• Reserved Capacity Pricing: If you're pushing >10TB monthly, consider CloudFront Reserved Capacity pricing for up to 30% savings
• Compression: Enable automatic compression to reduce transfer costs
• Smart TTL Settings: Longer cache times mean fewer origin requests

3 Common CloudFront Issues and Quick Fixes

Even the best setups hit snags. Here are solutions to common CloudFront headaches:

Cache Misses Too High?

• Check your TTL settings.
• Look for dynamic query parameters you can exclude from the cache key
• Consider invalidating objects instead of using short TTLs

Origin Connection Problems?

• Verify origin security groups/access settings.
• Check origin health with direct requests
• Set up origin timeout and retry settings correctly

SSL Certificate Issues?

• Make sure your certificate covers both your domain and any subdomains
• Certificates must be in the US East (N. Virginia) region for CloudFront
• Wait for ACM verification to complete (can take up to 24 hours)

Wrapping Up: Is CloudFront Right for You?

CloudFront makes the most sense when:

• You have a global audience
• Your site/app includes static assets (images, CSS, JS, videos)
• Performance and availability are priorities
• You're looking to reduce origin load

The setup process is straightforward, and the performance gains are immediate. Plus, with the cost savings from reduced origin load, CloudFront often pays for itself.

FAQs

How long does it take for content to be available after creating a CloudFront distribution?

It typically takes 5-10 minutes for a new CloudFront distribution to deploy across the global network. During this time, your distribution status will show as "In Progress." Once it changes to "Deployed," your content is available worldwide.

Can CloudFront work with non-AWS origins?

Absolutely! While CloudFront integrates seamlessly with S3 and other AWS services, you can use any publicly accessible web server as an origin. This includes on-premises servers, other cloud providers, or content management systems.

How does CloudFront pricing work?

CloudFront charges for:

1. Data transfer out to the internet
2. Number of HTTP/HTTPS requests
3. Invalidation requests (first 1,000 paths per month are free)
4. Real-time logs (if enabled)

Pricing varies by geographic region, with lower rates for regions like North America and Europe compared to South America or Australia. There's no upfront cost or commitment required.

What's the difference between CloudFront and Amazon S3 Transfer Acceleration?

Both speed up content delivery, but in different ways:

• CloudFront caches content at edge locations for faster delivery to end users
• S3 Transfer Acceleration speeds up uploads to S3 buckets by routing through the AWS network

Use CloudFront for delivering content to users, and Transfer Acceleration for uploading content to S3.

How can I invalidate content if it needs to be updated before the TTL expires?

You can create invalidations through the CloudFront console, AWS CLI, or API:

# Using AWS CLI
aws cloudfront create-invalidation --distribution-id DISTRIBUTION_ID --paths "/images/logo.png" "/css/*"

Remember that targeted invalidations (specific files) are more efficient than wildcard invalidations.

Does CloudFront support streaming media?

Yes, CloudFront supports both on-demand and live streaming. For on-demand, you can use standard HTTP progressive downloads or adaptive bitrate streaming formats like HLS and DASH. For live streaming, you can integrate with AWS MediaLive and MediaPackage.

Can I restrict access to my CloudFront content?

Definitely. CloudFront offers several security features:

• Signed URLs and Signed Cookies for limited-time access
• Geographic restrictions to block or allow specific countries
• Field-level encryption for sensitive data
• AWS WAF integration for protection against common web exploits

How does CloudFront handle HTTPS/SSL?

CloudFront makes SSL easy by integrating with AWS Certificate Manager (ACM). You can:

1. Request a free SSL certificate through ACM
2. Upload your existing certificate
3. Use the default CloudFront certificate (if you're using the default domain)

CloudFront supports modern TLS protocols and cipher suites for secure connections.

What's the difference between Lambda@Edge and CloudFront Functions?

Both allow you to run code close to your users, but with different capabilities:

• CloudFront Functions: Lightweight, millisecond execution, simple request/response manipulations
• Lambda@Edge: More powerful, can run longer, access to more runtime features

CloudFront Functions are significantly cheaper and have lower latency, so use them for simple tasks like URL rewrites or header manipulation.

Can CloudFront cache dynamic content?

While CloudFront works best with static assets, it can be configured for dynamic content too:

1. Use appropriate cache policies based on headers, cookies, and query strings
2. Implement stale-while-revalidate patterns
3. Use Lambda@Edge for personalization that doesn't impact cacheability

For dynamic content, focus on optimizing origin fetch performance rather than trying to cache everything.