This is a command line tool to cover a common use case. Specifically, suppose you have 2 servers (called server1 and server2 in the Linode Manager) as members of a NodeBalancer, and each of them is listening on ports 80 and 443. When you want to do maintenance on server1, it's quite a lot of clicks in the Linode Manager to accomplish this.
So using this tool, you can do
loadbalancer balancer1 server1 reject
This will take server1 completely out of rotation in the NodeBalancer, on all ports it is listening on. To bring it back online, use
loadbalancer balancer1 server1 accept
Which will bring it back.
In both cases, it will loop waiting for the change to actually propogate; when it has completed, and your changes have taken effect, the tool exits.
You can also use this with multiple load balancers at the same time; for example, if you have a server called server1, which is a member node in all of your NodeBalancers, you could use something like
loadbalancer ALL server1 reject
which will take server1 offline on all NodeBalancers configured on your account.
Uses the most excellent Linode gem; you'll need to install that gem first using
gem install linode
Then add your Linode API key to the file, make it executable in your file system, remove the .rb extension if you want, and you're good to go.