How to compare versions of an Amazon S3 object?

Question

Versioning of Amazon S3 buckets is nice, but I don't see any easy way to compare versions of a file - either through the console or through any other app I found.

S3Browser seems to have the best versioning support, but no comparison.

Is there a way to compare versions of a file on S3 without downloading both versions and comparing them manually?

--

EDIT: I just started thinking that some basic automation should not be too hard, see snippet below. Question remains though: is there any tool that supports this properly? This script may be fine for me, but not for non-dev users.

#!/bin/bash

# s3-compare-last-versions.sh

if [[ $# -ne 2 ]]; then
    echo "Usage: `basename $0` <bucketName> <fileKey> "
    exit 1
fi

bucketName=$1
fileKey=$2

latestVersionId=$(aws s3api list-object-versions --bucket $bucketName --prefix $fileKey --max-items 2 | json Versions[0].VersionId)
previousVersionId=$(aws s3api list-object-versions --bucket $bucketName --prefix $fileKey --max-items 2 | json Versions[1].VersionId)

aws s3api get-object --bucket $bucketName --key $fileKey --version-id $latestVersionId $latestVersionId".js"
aws s3api get-object --bucket $bucketName --key $fileKey --version-id $previousVersionId $previousVersionId".js"

diff $latestVersionId".js" $previousVersionId".js"

Answer 1

You can't view file contents at all via S3, so you definitely can't compare the contents of files via S3. You would have to download the different versions and then use a tool like diff to compare them.