Helps you diff systemd unit files as serialized by fleet.

Lets assume you've got a directory full of unit files, and you're uncertain which files in your remote fleet differ from the ones in your local repository.

You could try and diff the output of fleetctl cat, but if your unit file has any newlines in you'll get a false negative.

For example, lets say our unit has something like this:

ExecStart=/bin/bash -c ' \
  echo $(etcdctl get /hello)
'

This would look more or less like the following when using fleetctl cat

$ fleetctl cat hello.service
ExecStart=/bin/bash -c '  echo $(etcdctl get /hello) '

Doing a simple diff no longer works.

fleet-diff takes the output from fleetctl cat and the path to a local unit and then parses both using the unit package and then compares the units.

$ fleetctl cat hello.service | fleet-diff hello.service -
Everything looks fine.
$ echo $?
0

fleet-diff accepts two arguments, paths to unit files. If one of the paths is a - character, fleet-diff will read STDIN for the content.

fleet-diff will have an exit code of 0 if the units match, or 1 if they don't, making it easier to use in scripting.

$ fleetctl cat hello.service > hello-submitted.service
$ fleet-diff hello.service hello-submitted.service
Units are different!
$ echo $?
1

You need go installed to build the binary, then simply run:

$ go install https://bitbucket.org/mylightstone/fleet-diff

Go will place the final binary in your $GOPATH/bin directory, so make sure it is available in your $PATH.