Idem Release 3¶
This is the initial public release of Idem, the release number 3 was chosen because the Salt State system should be considered version 1, with an internal version 2.
This release introduces Idem to the world, it takes the Salt State system and migrates it to POP. In doing so the Salt State system has been simplified, extended, and revamped to become a standalone language and interface while following the ideals of POP to make it pluggable into other application stacks.
The Salt State system exists as a single large .py file inside of Salt, the compiler and runtime are all inside a couple of classes and the system is tightly coupled with the Salt minion and execution runtime and environment. This also made the Salt state system very static and difficult to extend. For instance, an old saying on the Salt developer team was “How do we create new requisites for Salt? Ask Tom to make it”.
My goal in Idem was to make it in such a way that it could be completely decoupled from Salt, modernize the foundation, add asyncio, and make the system easier to extend. Now the render, compile, and runtime have been separated out, the runtime has been completely rewritten and things like requisites can be added as plugins and runtime rules. Idem can also execute multiple runs concurrently within the same process, and can execute states in parallel or serially.
Idem can execute states in an imperative way or in a declarative way using requisites. This gives developers the best of both worlds. The ability to optimize execution for time or for ease of development and debugging.
The Idem command can be executed against a code tree directly just like a programming language. Instead of setting up minions, masters etc, just make a code tree with sls files and run Idem with the sls fils(s) you want to execute.
Code Sources are Pluggable¶
Instead of tying the runtime statically to grabbing sources via Salt, the sources are now pluggable. This release only has a local filesystem plugin but it will be easy to add code sources that are over network connections. This should make Idem execution function without needing to have any form of code deployment, but that Idem will be able to execute directly from any network source, like http, S3, or git.
Rendering is Separate¶
The render system in Salt turned out to be a generally useful system with virtually every attempt to read in files with structured data wanting to be processed though the render system. So for Idem the render system has been separated into a standalone project called rend. This project is written in POP and can be app-merged into any other POP project (like idem!). This makes the powerful render system from Salt available to other projects. In fact it is already being used bu other projects like heist.
Idem is a Language Runtime¶
One of the main issues with configuration management tools is that we end up needing to re-write the backend components to work in additional languages and interfaces. The goal of Idem is to make this limitation go away! Instead of making yet another language, Idem ingests structured data. This means that any language can be written on top of Idem as an extension to rend. So Idem can be seen not as a yaml based language for idempotent management. But instead as assembly code that languages can be built on top of.
I feel that the language war in configuration management is one of the primary limiting factors for the industry, and why we end up producing new languages to solve specific problems. My hope here is that support for all the managed interfaces can be built into Idem and then made available to any app that wants to use them.