Orchestration made easy with Gru v0.2.0

For the past few months I've continued working on my first Go project and overall I am very pleased with how the project evolved as a whole.

Over this time a lot of improvements have made into the project, and here are just some of them.

The new version of Gru has introduced resources as a way to declare and execute idempotent operations, making the project better suited for things such as configuration management as well.

Gru has also adopted HCL as the configuration language, which is used to express resources. Resources can now be grouped together into modules, which allows for code re-use by making it possible modules to import other modules.

This is how a package resource can be expressed in HCL for example.

// Installs the tmux package
package "tmux" {
  state = "present"
}

Using DAG graphs we can now have relationship between resources, allowing us to express what the resource evaluation order should be.

file "/home/dnaeon/.tmux.conf" {
  state = "present"
  mode = 0644
  source = "data/tmux/tmux.conf"
  require = [
    "package[tmux]",
  ]
}

Once we do a topological sorting of the resource graph nodes, we can evaluate and process our resources in the correctly specified order, or detect circular dependencies in our resources.

Another new feature which was introduced in version 0.2.0 of Gru is the site repo, which basically allows the remote minions to sync modules and data files from upstream Git repository. Each branch from the site repo also represents an environment, which minions can checkout and use during the catalog processing.

Having support for different environments, means that each minion can track different branch from the site repo, and also makes testing of new features and modules much easier, since you can push an environment to just specific minions, while the rest of them continue to track the production environment.

With this release we can also make use of some core resources, such as service, file, shell, pacman, yum and others.

I've also finally caught up on actually writing some documentation about Gru, so now you will be able to find the Gru Quickstart Guide, which will walk you through your first steps with Gru.

The latest Gru documentation you can find here and you can also see how a module in Gru looks like expressed in HCL at the example site repo for Gru.

Finally, I'd like to say that when I first started working on this project I had no idea how it will evolve, but over the time new features have been implemented, fixes have been made as well, and overall I had the chance to cover a lot of ground using the Go programming language, which made this whole experience working on this project so much fun!

Written on May 28, 2016