After the last days dispair fighting with packaging jar files and configuration management in order to deploy the system on a set of servers, I’ve yesterday worked with something delightful: Fabric.
I posed this question to a hacker-friend of mine: what is the easiest way to deploy and run a set of configuration commands on five machines. The only requirement? It shouldn’t take me forever to set-up.
He immediately posted a snippet of python code using the Fabric library.
Fabric is a “tool for streamlining the use of SSH for application deployment or systems administration tasks”. And what’s more, it’s super-easy to use and has good documentation!
By defining small tasks, which are composeable, you declare commands to run on remote machines. You can execute commands locally too. With three commands and a few tasks I had the whole procedure set-up: Packaging jar files, moving them to one of the remote servers, distributing them from there to the others (our upload capacity is kind of slow), uploading the test data, generating a configuration template, uploading this one, generating host-specific configurations based on the template, and finally (re)starting the application.
Generating and uploading configuration files look like this:
And can be run by issuing fab prepare_config:data=sample,maxcap=20 config.
Happy deploying!