Restore an older S3 object version

Part 24 of AWS from Zero. Today we make an older value current again without destroying version history.

What we are learning

Copying a specific older version onto the same key creates a new current version containing the older data. The original versions remain available.

Before you run it

REGION="ap-south-1"
BUCKET="aws-zero-restore-version-12345"
KEY="settings.txt"
 
aws s3api create-bucket \
  --bucket "$BUCKET" \
  --region "$REGION" \
  --create-bucket-configuration LocationConstraint="$REGION"
 
aws s3api put-bucket-versioning \
  --bucket "$BUCKET" \
  --versioning-configuration Status=Enabled
 
echo "stable settings" > settings.txt
STABLE_VERSION=$(aws s3api put-object \
  --bucket "$BUCKET" \
  --key "$KEY" \
  --body settings.txt \
  --query VersionId \
  --output text)
 
echo "broken settings" > settings.txt
BROKEN_VERSION=$(aws s3api put-object \
  --bucket "$BUCKET" \
  --key "$KEY" \
  --body settings.txt \
  --query VersionId \
  --output text)

Inspect the history

aws s3api list-object-versions \
  --bucket "$BUCKET" \
  --prefix "$KEY" \
  --query "Versions[].{Version:VersionId,Latest:IsLatest,Updated:LastModified}" \
  --output table

Restore the stable version

RESTORED_VERSION=$(aws s3api copy-object \
  --bucket "$BUCKET" \
  --key "$KEY" \
  --copy-source "$BUCKET/$KEY?versionId=$STABLE_VERSION" \
  --query VersionId \
  --output text)

The copy receives a new version ID and becomes current.

Verify the content

aws s3 cp "s3://$BUCKET/$KEY" restored-settings.txt
cat restored-settings.txt

You should see stable settings.

One tiny variation

You can retrieve an old version without making it current:

aws s3api get-object \
  --bucket "$BUCKET" \
  --key "$KEY" \
  --version-id "$BROKEN_VERSION" \
  broken-settings.txt

Common mistake

The --copy-source value must be URL encoded when the key or version ID contains characters that are not safe in a URL. Always preserve the exact version ID returned by S3.

Restoring by copy creates another stored version, so it does not reduce storage usage.

Cleanup

aws s3api delete-object --bucket "$BUCKET" --key "$KEY" --version-id "$STABLE_VERSION"
aws s3api delete-object --bucket "$BUCKET" --key "$KEY" --version-id "$BROKEN_VERSION"
aws s3api delete-object --bucket "$BUCKET" --key "$KEY" --version-id "$RESTORED_VERSION"
aws s3api delete-bucket --bucket "$BUCKET" --region "$REGION"
rm settings.txt restored-settings.txt broken-settings.txt

Next, we will configure and verify explicit SSE-S3 default encryption.

AWS guide to restoring previous versions