I’ve been working with Chef at work and there are several items that I keep looking up.\u00a0 The first of these is calculating the checksum for a file that chef downloads.\u00a0 Since we are doing some customized recipes I keep looking at having to grab a file and check the checksum, although not completely necessary it is a nice to have.\u00a0 For example formatting the EBS volumes I use something that looks like this:<\/p>\n
remote_file \"#{Chef::Config[:file_cache_path]}\/format9-11-13.sh\" do\r\nsource \"http:\/\/somebucket.s3.amazonaws.com\/format.sh\"\r\nchecksum \"70b8c25a25fb0aeca95b89d33571b6021a334ebbb706444fd266a6d73104f62c\"\r\nend<\/code><\/pre>\nFor Chef<\/strong> you need to use the following:<\/p>\nshasum -a 256 \/path\/to\/file<\/code><\/pre>\nThat will generate the checksum you need in your cookbook. You don’t need to use the whole thing either, just a portion is needed as shown here:\u00a0https:\/\/coderwall.com\/p\/bbfjrw<\/a><\/p>\n <\/p>\n
To calculate a checksum normally use the SHA-256 algorithm. Most of the time you would use the built-in cksum command like so:<\/p>\n
$ cksum sample\r\n2072207789 477 sample<\/code><\/pre>\nWhere the CRC (Cyclical Redundancy Check) or checksum is the first number then the size then the name of the file.<\/p>\n","protected":false},"excerpt":{"rendered":"
I’ve been working with Chef at work and there are several items that I keep looking up.\u00a0 The first of these is calculating the checksum for a file that chef downloads.\u00a0 Since we are doing some customized recipes I keep looking at having to grab a file and check the checksum, although not completely necessary<\/p>\n