Backup Gridfs files as normal files

This is the monster I created to get gridfs files backed up as if they where on filesystem:

One thing I wanted was to keep the script in one file, and to make it work with the least dependencies possibile.

This is what it does with the dump commnad

  • dump all collections but fs.chunks as usual, with mongodump
  • Gzip all bson files
  • create a directory for grids files
  • dump gridfs files to filesystem via Ruby, only if id+checksum did not change
  • remove fs files that are no longer in the database

On restore

  • unzip bson files
  • restore the database from bson files
  • iterate over fs.files collection, read dumped file from filesystem and restore it into gridfs.

The operations above can be performed on a subset of databases.

I learned a couple of things working on this script:

  • What :snapshot => true is for. I ended up in an endless loop on restore. Cursor was beeing fed with new records on every iteration.
  • Authentication in mongodb is painful. You have to add admin user to each and every database in order to make this script work for the whole instance when –auth is on.



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