A shell script for uploading a React app build to S3 + CloudFront for deployment

react-app-s3-sync.sh

#!/bin/bash

S3_BUCKET_NAME=$1
CF_ID=$2

# Sync all files except for service-worker and index
echo "Uploading files to $S3_BUCKET_NAME..."
aws s3 sync build s3://$S3_BUCKET_NAME/ \
  --acl public-read \
  --exclude service-worker.js \
  --exclude index.html

# Upload service-worker.js with directive to not cache it
echo "Uploading service-worker.js"
aws s3 cp build/service-worker.js s3://$S3_BUCKET_NAME/service-worker.js \
  --metadata-directive REPLACE \
  --cache-control max-age=0,no-cache,no-store,must-revalidate \
  --content-type application/javascript \
  --acl public-read

# Upload index.html
echo "Uploading index.html"
aws s3 cp build/index.html s3://$S3_BUCKET_NAME/index.html \
  --metadata-directive REPLACE \
  --cache-control max-age=0,no-cache,no-store,must-revalidate \
  --content-type text/html \
  --acl public-read

# Purge the cloudfront cache
echo "Purging the cache for CloudFront"
aws cloudfront create-invalidation \
  --distribution-id $CF_ID \
  --paths /

@john-osullivan @joaoportela the invalidation is needed as all other files except index and serviceworker might have been cached depending on cloudfront settings

@Fantaztig I think we are all assuming that all rest of the files are cache-busted (or have unique names) altogether. That's what I understand the whole point of this task is:

Cache-Control: no-cache.... for those files (as they're entry points into app)

• index.html
• service-worker.js

Those files are cache busted:

• js/some-bundle.0123213123.js
• js/some-vendor-bundle.1231232432.js
• css/some-style.123123213.css

And those files are have unique names (uploaded only once, and if you want to replace the image, you simply upload file under new name):

• img/logo-main.123123213.png
• img/blog-images/header.123123213.png
• img/blog-images/header.2342343242.png
  etc.

Thus taking this approach you would never need to perform CloudFront cache-invalidation. (As imagine you have 100,000 files in your cache? are you going to be invalidating all 100,000 each time you replace image in an earlier blogpost?)

Oh I See! Thanks for the hint.
Tbh for best performance it would be a good idea to use s-max-age to let cloudFront cache those two files and use the invalidation to explicitly invalidate them on updating the bucket

@Fantaztig no. because those headers also go to the clients (browsers usually) and you have no way of invalidating those.

As a rule of thumb, if you have to purge cloudfront cache its because you messed up somewhere.

@joaoportela the s-max-age header is irrelevant to the client, but can be used to tell cloudFront how long to cache a file.
https://docs.aws.amazon.com/AmazonCloudFront/latest/DeveloperGuide/Expiration.html#ExpirationDownloadDist

@Fantaztig , @joaoportela thanks for those interesting thoughts and remarks! It's very useful! It makes configuring cache less of a nightmare... :)

@joaoportela the s-max-age header is irrelevant to the client, but can be used to tell cloudFront how long to cache a file.
https://docs.aws.amazon.com/AmazonCloudFront/latest/DeveloperGuide/Expiration.html#ExpirationDownloadDist

You're correct. I somehow missed the s- prefix when reading your comment.

Personally, I would still avoid using that technique. But it is a valid and correct approach.