Deploy changed assets to S3 and generate a CloudFront invalidation.

aws-s3-cloudfront-deploy.sh

#!/bin/bash

set -e

# must set BUCKET and CLOUDFRONT_DIST_ID environment variables
PROJECT_BASE=$(cd "$(dirname "$0")/../" && pwd)

# change directories into project base
cd "$PROJECT_BASE"

# this script deploys changed assets to S3 and creates and awaits an invalidation to CloudFront
upload_result_file=$(mktemp)
modified_file=$(mktemp)
invalidation_result_file=$(mktemp)

function cleanup() {
  rm $upload_result_file $modified_file $invalidation_result_file
}

function fail() {
  cleanup
  echo ERROR: $@ >&2
  exit 1
}

# sanity check utility presence
which aws >/dev/null || fail "AWS CLI not found."
which jq >/dev/null || fail "jq not found."

# sanity check bucket and cloudfront definition
if [ -z "$BUCKET" ]; then
  fail "BUCKET environment variable not defined."
fi

if [ -z "$CLOUDFRONT_DIST_ID" ]; then
  fail "CLOUDFRONT_DIST_ID environment variable not defined."
fi

# enable cloudfront preview if it's not already enabled
if [[ "$(aws configure get preview.cloudfront)" != "true" ]]; then
  echo "Enabling AWS CloudFront Preview Support."
  aws configure set preview.cloudfront true
  echo
fi

# upload changed files
echo "Syncing assets to S3..."
aws s3 sync --sse AES256 site/ s3://$BUCKET/ | tee $upload_result_file
echo

# gather a list of changed files for invalidation
cat $upload_result_file | grep -oP '(?<=upload: ).+(?= to )' | sed 's:^site/::' \
    > $modified_file

# if no files were modified, just exit out
if [[ $(cat $modified_file | wc -l) -eq 0 ]]; then
  echo "No files modified, nothing to do."
  cleanup
  exit 0
fi

# start the invalidation; note: paths must be prefixed with slash
echo "Creating CloudFront Invalidation..."
cat $modified_file | sed 's:^:/:g' | xargs -t -I {} --no-run-if-empty \
    aws cloudfront create-invalidation --distribution-id $CLOUDFRONT_DIST_ID \
        --paths {} | tee $invalidation_result_file
echo

# extract the invalidation id
invalidation_id=$(jq -r '.Invalidation.Id' $invalidation_result_file)

echo "Invalidation $invalidation_id Created."
echo

cleanup
exit 0