SOUTHWORKS Dev Team
November 2, 2020
Pulumi is an open-source multi-language and multi-cloud development platform, which allows you to manage your whole cloud infrastructure, like VMs, networking, databases, modern architectures, serverless functions, and containers, just by coding.
Using Pulumi you will be able to:
Infrastructure as code (sometimes referred to as programmable or software-defined infrastructure) is a very important DevOps practice for every project, its objective is to make the process of achieving CI/CD more maintainable and scalable. By writing high-level code to deploy, update, and destroy cloud infrastructure, it becomes really easy to maintain and scale if you follow good practices. It isn’t the same to have to create new services manually in your cloud console, that calling a function one more time, or adding some more lines of code.
As the infrastructure is also code, it can go through the same version control, automated testing process, and different steps of a continuous integration and continuous delivery (CI/CD) pipeline that developers use for their application code.
We live in a world where everything tends to be automated, having that in mind, designing code that can be run automatically every time something happens, or in a determined time, is a great idea. You can schedule your code to deploy the whole infrastructure early in the morning, so you have it available for the day, and in the evening, when you aren’t using any resource, destroy cloud resources so you don’t waste money.
Learning how to deploy infrastructure as code might need some training, but when you understand how it works, and get familiar with it, it becomes a really useful tool for your projects.
Pulumi is a modern infrastructure as code platform. It includes a CLI, libraries, and a hosted service that, working together, deliver a robust way of provisioning, updating, and managing cloud infrastructure.
Pulumi has its own programming model to deploy infrastructure, it manages different resources using the Pulumi SDK, this programming model and SDK introduces new concepts, such as programs, projects, and stacks to manage the resources’ deployment, and inputs and outputs to manage dependencies between resources, that you have to understand and use in order to make your deploy successful.
The Pulumi’s programming model contains core concepts that you need to know to write your infrastructure as code.
A Pulumi project is conformed by three components:
A project is a directory that includes a program and a .yaml file with configurations that lets Pulumi know how to run the program.
The Pulumi.yaml file contains important metadata such as the name and a description of the project, the programming language chosen, and more optional configurations.
A program is a collection of files that the project uses to run. These files are written in the programming language that is defined in the Pulumi.yaml file.
As Pulumi programs are written in familiar languages, you can use their natives libraries, but in order to deploy your infrastructure, you will also need to use Pulumi’s packages and their resource types. You can set your program to generate outputs that will be available in the stack that is running it.
When you run your program using the Pulumi CLI, you will see a preview of the resources that are going to be created, updated, or destroyed, depending on your code and their current status.
A stack is an instance of a project, you can have as many stacks as you want, they are usually used for different cloud environments, stages, or branches. Each stack has its own Pulumi.<stack>.yaml file, so it can be configured independently.
You can do basic operations like create, select, and destroy stacks using the CLI, also, it provides you more specific features such as listing, tagging, importing and exporting stacks, and viewing their outputs.
There are some best practices and different approaches when organizing your code when using Pulumi. Namely, we could have a Monolithic or a Micro-stacks approach.
It’s very common to start using Pulumi with a monolithic approach, where a single project defines the infrastructure and application resources for an entire vertical service including all the different stacks used for different environments (ex., production, staging, testing).
These are some benefits of using a monolithic approach:
Using a monolithic structure is where most users begin, but in turn, choosing a finer-grained decomposition of projects and stacks brings its own advantages.
Micro-stacks is a pattern where the project is broken into separately managed smaller projects. For example, defining the cluster infrastructure in one project and consume it from another. It is possible to even break it in more projects for different environments, said production, staging, and testing.
This approach raises the question of managing dependencies between your stacks. To manage inter-stack dependencies, Pulumi uses stack exports, where in one stack you export a service output property and in another one you consume it.
Here are a few examples of how to split up a monolithic project:
Let’s see the advantages of this approach:
Pulumi uses states to define what operation should be done to each resource.
The Pulumi state model is based on four different components:
You can interact in different ways with a project, and Pulumi will act according to that:
Basically, the Pulumi deployment engine does the following operations for each resource that has to be deployed:
If the resource hasn’t been created yet:
If the resource has been created:
5. Updates the resource’s state.
For a component it works the same way, but the language host will make multiple resources registration requests, and the children will run when the father’s current state equals it’s desired one.
If you have come all the way down here, you’re probably wondering “How do I start deploying my infrastructure using Pulumi?”.
The first thing you should do, if you haven’t already, is choosing the cloud provider and language that you are going to use. With that decision already made, the Pulumi getting started documentation will guide you to install Pulumi and configure the cloud provider and language you chose before, after that, it will show you how to create and deploy a basic project, also, you’ll be able to destroy the whole stack.
Once you have a basic project deployed, it’s time to dig into the documentation and start developing your own solutions. Check the API reference to deploy different services to the cloud.
Originally published by Gonzalo Muñoz for SOUTHWORKS on Medium 2 November 2020