Serving Multiple S3 Buckets with a Single Cloudfront Distribution: A Common Challenge
Problem: You want to efficiently serve static content from multiple Amazon S3 buckets using a single CloudFront distribution. However, you're facing limitations and encountering errors.
Simplified Explanation: Imagine you have two online stores, each with its own product images stored in separate S3 buckets. You want to use a single CloudFront distribution to deliver these images to customers, but it doesn't seem to work as expected.
Scenario & Original Code:
Let's assume you have two S3 buckets: bucket1 and bucket2. You want to serve content from bucket1 for paths starting with /store1/ and content from bucket2 for paths starting with /store2/.
# Example CloudFront configuration
{
"Origins": {
"DefaultOrigin": {
"DomainName": "bucket1.s3.amazonaws.com",
"S3OriginConfig": {
"OriginAccessIdentity": "cloudfront:your_access_identity"
}
},
"Origin2": {
"DomainName": "bucket2.s3.amazonaws.com",
"S3OriginConfig": {
"OriginAccessIdentity": "cloudfront:your_access_identity"
}
}
},
"DefaultCacheBehavior": {
"TargetOriginId": "DefaultOrigin",
"ViewerProtocolPolicy": "redirect-to-https",
"AllowedMethods": [
"GET",
"HEAD"
],
"CachedMethods": [
"GET",
"HEAD"
]
},
"CacheBehaviors": {
"Behavior2": {
"TargetOriginId": "Origin2",
"PathPattern": "/store2/*",
"ViewerProtocolPolicy": "redirect-to-https",
"AllowedMethods": [
"GET",
"HEAD"
],
"CachedMethods": [
"GET",
"HEAD"
]
}
}
}
Analysis:
This configuration might appear to work, but it has a critical flaw. The "DefaultCacheBehavior" applies to all requests by default, including those targeting /store2/. This leads to all requests being directed to bucket1, regardless of the path.
Solution:
To address this, you need to define separate Cache Behaviors for each S3 bucket and ensure that the "DefaultCacheBehavior" is configured to handle only requests that don't match any of the other behaviors. This ensures that each request is directed to the appropriate S3 bucket based on the path.
Revised Configuration:
# Example CloudFront configuration
{
"Origins": {
"DefaultOrigin": {
"DomainName": "bucket1.s3.amazonaws.com",
"S3OriginConfig": {
"OriginAccessIdentity": "cloudfront:your_access_identity"
}
},
"Origin2": {
"DomainName": "bucket2.s3.amazonaws.com",
"S3OriginConfig": {
"OriginAccessIdentity": "cloudfront:your_access_identity"
}
}
},
"DefaultCacheBehavior": {
"TargetOriginId": "DefaultOrigin",
"ViewerProtocolPolicy": "redirect-to-https",
"AllowedMethods": [
"GET",
"HEAD"
],
"CachedMethods": [
"GET",
"HEAD"
],
"ForwardedValues": {
"QueryString": false
}
},
"CacheBehaviors": {
"Behavior2": {
"TargetOriginId": "Origin2",
"PathPattern": "/store2/*",
"ViewerProtocolPolicy": "redirect-to-https",
"AllowedMethods": [
"GET",
"HEAD"
],
"CachedMethods": [
"GET",
"HEAD"
],
"ForwardedValues": {
"QueryString": false
}
}
}
}
Additional Considerations:
- Path Matching: Carefully define the
PathPatternfor each Cache Behavior to ensure correct routing of requests. - Caching: Configure appropriate caching policies for each bucket to optimize content delivery.
- Origin Access Identity: Ensure a unique Origin Access Identity is used for each S3 bucket to restrict access from CloudFront.
Conclusion:
By correctly configuring Cache Behaviors and ensuring the "DefaultCacheBehavior" only handles unmatched requests, you can successfully serve content from multiple S3 buckets with a single CloudFront distribution. This approach provides a flexible and efficient solution for serving static content from various sources.
References:
