File format checks

This is the repository for the backend file format check for the Transfer Digital Records project.

The file format checks run in AWS Lambda. They run the DROID file format tool to extract PRONOM IDs.

The Lambda function downloads the file passed as input to the lambda local file system.

The function then calls the Droid API against this file to extract the PRONOM ids

Deployment

DROID and file format signatures

Droid is contained within the "uk.gov.nationalarchives" % "droid-api" dependency. The binary and container signature files are downloaded when the lambda is first started. To get the signature files, it carries out the following steps.

• Checks to see if the /tmp directory contains container-* or DROID_Signature*
• If they exist, use those to create the Droid instance.
• If they don't exist:
  • Call http://www.nationalarchives.gov.uk/pronom/container-signature.xml and get the last modified date
  • Convert this to YYYYMMDD and use that for the container signature version
  • Call the SOAP endpoint at http://www.nationalarchives.gov.uk/pronom/service.asmx
  • This returns the latest Droid signature file version.
  • Download both these files from the TNA CDN as before.

File format Lambda

To deploy changes to the Lambda which downloads the file from S3 and runs DROID, run the deploy GitHub actions job.