Compare the last two versions of a file stored in a S3 bucket

version_compare.sh

#!/bin/bash

#This script needs awscli, jq and colordiff. Please install them for your environment

#This script also needs the AWS_ACCESS_KEY_ID, AWS_SECRET_ACCESS_KEY and AWS_DEFAULT_REGION.

#Please set them using the export command as follows or set them using envrc
#export AWS_ACCESS_KEY_ID=<Your AWS Access Key ID>
#export AWS_SECRET_ACCESS_KEY=<Your AWS Secret Access Key>
#export AWS_DEFAULT_REGION=<Your AWS Default Region>

set -e

if [ -z $1 ] || [ -z $2 ]; then
echo "Usage:"
echo "version_compare.sh *bucket_name* *file_name*"
echo
echo "Example"
echo "version_compare.sh bucket_name folder/filename.extension"
echo
exit 1;
fi


aws_bucket=$1
file_key=$2

echo Getting the last 2 versions of the file at ${file_key}..

echo
echo Executing:
cat << EOF
aws s3api list-object-versions --bucket ${aws_bucket} --prefix ${file_key} --max-items 2
EOF
echo
versions=$(aws s3api list-object-versions --bucket ${aws_bucket} --prefix ${file_key} --max-items 2)
version_1=$( jq -r '.["Versions"][0]["VersionId"]' <<< "${versions}" )
version_2=$( jq -r '.["Versions"][1]["VersionId"]' <<< "${versions}" )

mkdir -p state_comparison_files

echo Getting the latest version ${version_1} of the file at ${file_key}..
echo
echo Executing:
cat << EOF
aws s3api get-object --bucket ${aws_bucket} --key ${file_key} --version-id ${version_1} state_comparison_files/${version_1}
EOF
aws s3api get-object --bucket ${aws_bucket} --key ${file_key} --version-id ${version_1} state_comparison_files/${version_1} > /dev/null

echo
echo Getting older version ${version_2} of the file at ${file_key}..
echo
echo Executing:
cat << EOF
aws s3api get-object --bucket ${aws_bucket} --key ${file_key} --version-id ${version_2} state_comparison_files/${version_2}
EOF
aws s3api get-object --bucket ${aws_bucket} --key ${file_key} --version-id ${version_2} state_comparison_files/${version_2} > /dev/null

echo
echo Comparing the different versions.
echo If no differences are found, nothing will be shown
colordiff --unified state_comparison_files/${version_2} state_comparison_files/${version_1}