remote_file_prevent_re_downloads.md

To prevent Chef Infra Client from re-downloading files that are already present on a node, use one of the following attributes in a recipe: use_conditional_get (default) or checksum.

• The use_conditional_get attribute is the default behavior of Chef Infra Client. If the remote file is located on a server that supports ETag and/or If-Modified-Since headers, Chef Infra Client will use a conditional GET to determine if the file has been updated. If the file has been updated, Chef Infra Client will re-download the file.
• The checksum attribute will ask Chef Infra Client to compare the checksum for the local file to the one at the remote location. If they match, Chef Infra Client will not re-download the file. Using a local checksum for comparison requires that the local checksum be the correct checksum.

The desired approach just depends on the desired workflow. For example, if a node requires a new file every day, using the checksum approach would require that the local checksum be updated and/or verified every day as well, to ensure that the local checksum was the correct one. Using a conditional GET in this scenario will greatly simplify the management required to ensure files are being updated accurately.