What is Salt?
We’re not just talking about NaCl.
Distributed Remote Execution
Salt is a distributed remote execution system used to execute commands and query data. It was developed in order to bring the best solutions found in the world of remote execution together and make them better, faster and more malleable. Salt accomplishes this via its ability to handle larger loads of information, and not just dozens, but hundreds, or even thousands of individual servers. It handles them quickly and through a simple yet manageable interface.
Versatility between massive scale deployments and smaller systems may seem daunting, but Salt is very simple to set up and maintain, regardless of the size of the project. The architecture of Salt is designed to work with any number of servers, from a handful of local network systems to international deployments across disparate datacenters. The topology is a simple server/client model with the needed functionality built into a single set of daemons. While the default configuration will work with little to no modification, Salt can be fine tuned to meet specific needs.
The core function of Salt is to enable remote commands to be called in parallel rather than in serial. It does this over a secure and encrypted protocol using the smallest and fastest network payloads possible. All of this is possible and salt still manages to have a simple interface for developers. Salt also introduces more granular controls to the realm of remote execution, allowing for commands to be executed in parallel and for systems to be targeted based on more than just hostname, but by live system properties.
Building on Proven Technology
Salt takes advantage of a number of technologies and techniques. The networking layer is built with the excellent ZeroMQ networking library. Salt itself contains a viable, and transparent, 0MQ broker inside the daemon. Salt uses public keys for authentication with the master daemon, then uses faster AES encryption for payload communication. This means that authentication and encryption are also built into Salt. Salt takes advantage of communication via the most excellent msgpack library, enabling fast and light network traffic.
Python Client Interface
Salt execution routines can be written as plain Python modules and the data collected from execution can be sent back to the master server, or any arbitrary program. Salt can be called from a simple Python API, or from the command line. This makes it easy to execute one-off commands as well as operate as an integral part of a larger application.
Fast, Flexible, Scalable, Secure
The result is a system that can execute commands across groups of varying size, from very few to very many servers at considerably high speed. We consider speed to be a feature, not an afterthought. Salt’s unique architecture brings together the best of the remote execution world, amplifies its capabilities and expands its range, resulting in this system that is as versatile as it is practical. Last but not least, security is an intrinsic part of salt and something not just influencing how source code is written and how tests are done, but also something that defines the overall architecture and has heavy influence on the core design tenants.
Salt is developed under the Apache 2.0 licence, and can be used for open and proprietary projects. Please submit your expansions back to the Salt project so that we can all benefit together as Salt grows. Finally, please sprinkle some salt around your systems and let the deliciousness come forth.