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Amazon web services – How to Remove User-Defined Metadata from All Objects in S3 Buckets Using AWS CLI?

I’m looking to remove specific user-defined metadata from all objects across our S3 buckets to eliminate data duplication, as we’re storing the metadata externally. Given the large number of objects, updating each one manually isn’t feasible. I’m aware that modifying an object’s metadata in S3 results in creating a new copy of the object with updated metadata, along with a new "last modified" date, and I am fine with this behaviour.

Given the scale of our S3 usage, manually updating each object is not a practical approach. Therefore, I’m seeking a method to automate this process using the AWS CLI. The primary objectives are:

  1. Iterate through every object in specified S3 buckets.
  2. Remove specified user-defined metadata from these objects without altering the object data itself.
  3. Ensure the process maintains the integrity of the original objects, aside from the necessary update to the metadata and "last modified" date.

I am looking for guidance on how to construct AWS CLI commands or scripts capable of achieving this efficiently and with minimal disruption. Also, any insights into best practices for managing large-scale metadata updates in S3 would be highly valuable.

Thank you.

Source:

Editing object metadata in the Amazon S3

Working with Object Metadata: AWS S3

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2

Answers


  1. Chosen as BEST ANSWER
    0

    Thanks to @John Rotenstein. Building on that aws cli command, this is how I was able to iterate through all the objects in a bucket and remove its user-defined metadata.

    In case you want to make changes to the metadata throughout all objects in a bucket without deleting them completely, this can still work except you need to add the key-value pairs you want to add to the metadata. Please note that it creates a new copy of the object, which means it only keeps the metadata you add in the command, the rest of everything will be deleted.

        #!/bin/bash

    SOURCE_BUCKET="source bucket"
    DEST_BUCKET="dest_bucket"
    KMS_KEY_ID="kms_key_id"

    # Fetch object keys, replace tabs with newlines, and process each key for copying
    aws s3api list-objects --bucket "$SOURCE_BUCKET" --query 'Contents[].Key' --output text | tr 't' 'n' | while read -r OBJECT_KEY
    do
      echo "Processing ${OBJECT_KEY}..."
  
      aws s3api copy-object 
    --copy-source "${SOURCE_BUCKET}/${OBJECT_KEY}" 
    --key "${OBJECT_KEY}" 
    --bucket "$DEST_BUCKET" 
    --metadata-directive REPLACE 
    --ssekms-key-id "$KMS_KEY_ID" 
    --server-side-encryption "aws:kms"
  
      if [ $? -eq 0 ]; then
        echo "Successfully copied ${OBJECT_KEY}."
      else
        echo "Error copying ${OBJECT_KEY}."
      fi
    done

  2. 0

    You can remove the metadata when performing the copy by using:

    aws s3 cp s3://my-bucket/my-object s3://my-bucket/my-object --metadata-directive REPLACE

    As per the cp — AWS CLI Command Reference:

    If REPLACE is used, the copied object will only have the metadata values that were specified by the CLI command.

    To update all objects, you’ll first need to list the objects and then run the above command against each of them. It might be easier doing this in a programming language (eg Python) but if you have good shell scripting skills you can do it using the AWS CLI.

    Sometimes I cheat and put the object listing in Excel, then build a formula that will perform this type of operation. I Copy-Down to make the commands for every object. I then shove the result into a text file and execute it with the shell.

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