Terraform has built-in support for modules, and we're going to use this as the base building block to change our Terraform setup. And we did this by taking a journey through a representative set of clients and looking at the pain points that they had along the way, and how they can evolve things. So we have Terry. The infrastructure is relatively simple. And this is a massive bonus in terms of reducing the risk from an operational perspective of at least not destroying your production infrastructure as you go along. Crucially, because all of the modules are configurable, there's a very clear contract which means that for the different environments we can start configuring things differently. So it's a single place that people can see what's going on. I've put a here because I want to show how you move to the remote state and move forward. There’s only one outer loop at the resource level. Terry's chuffed. We had the VPC in the subnet, and this changes now to suddenly being composed of modules itself. And she's got some new team members that she wants to teach the ropes. However, there's a bootstrap problem here: Who builds the infrastructure that builds the infrastructure? Now the primary issue with the Terralith is that you can't manage the individual environments differently. So, you can output things from Terraform and have scripts which scrape it and then try and somehow get it into Puppet and Ansible or whatever. We want to make sure that the modules have got a clear contract as to what we expect the inputs and the outputs to be. There was a single Git repository. Example the variable below contains an object and a nested object inside a variable: ... a standalone example is a must but if the module can be used with another terraform module, examples for using with that module may be included as well. So the services needing to make use of these particular environments, they also then use, they change the Terraform remote state file to now refer to the S3 backend instead of the local backend. They are unable to change one part of the system without seemingly affecting an unrelated other part of their infrastructure. And for any database needs, we're going to use Amazon RDS to make that possible. And that's made the setup more DRY or ‘Don't Repeat Yourself,’ which is the programmer's acronym. Now you've suddenly got to coordinate amongst each other and make sure you don't overwrite everybody's stuff, make sure you're working off the latest code.. And from a human perspective, and at least not stepping on everybody's toes, moving to actual proper remote setup, something like S3 is a massive winner at least from that perspective. Conditional creation. Sometimes, people will end up creating their own separate module repository. However, this is probably unexpected and undesirable behavior. To begin with, we start with an Amazon VPC, we have a public subnet where we're going to have things like a NAT gateway, a bastion box, and then we've also got a single private subnet, where we're going to house our Kubernetes cluster. Now we're composing it with modules, and we're passing in different values. And then you have the logical or the system-specific modules which are the ones that we've seen now. The example over here is we have our core module, and that creates our private subnet, and we need that private subnet ID to be able to be passed as input, into our Kubernetes cluster module, so that we can make sure it gets created in the right subnet. Because of this, any changes to local modules will be effective immediately, without having to re-run terraform get. These types of resources supported: CloudFront distribution; CloudFront origin access itentify; Terraform versions. (Get-Module -ListAvailable -All).count Excluding the CIM modules, there are 44 modules 0. We’ve covered loops fundamentals in the previous two blog posts: We’re building on top of those learnings, so if you have not read those posts yet, it’ll be helpful to go back and understand those posts. So in terms of how you configure the components that want to now consume another component, it starts looking something like this. Additionally, we didn't quite go into detail on this, but with the Terraservices setup, sometimes what people end up doing is, they don't create the infrastructure, they also will invoke a provisioning tool, so something like Ansible or Puppet, in order to install software on the box afterwards. And you'll see things like Terragrunt and Terrahelp and various combinations of systems coming together to create the tooling that ultimately is used to build your infrastructure. Terraform - Adding a new resource instance and resoring terraform state . So our original pain points that we had with the Terralith were that we couldn't manage our environments separately, it's quite hard to understand, and there was a lot of maintenance, in terms of the duplication. And the boss thinks, “I needed this production infrastructure yesterday, please can you create it?”. Posted by 5 days ago. In fact, she's building a team now. But she thinks, “well maybe I can do a little bit better. So, this is great. So how do I know that I need to run my core module first and then my Kubernetes. And not everybody pools from Git religiously, and although there are warnings when they run Terraform, it's still a little bit painful. Then there's the Kubernetes cluster, which is going to hold the Kubernetes setup, and a separate area for the database. And she likes what she sees; she's quite happy with this. We're then also going to briefly look at the related topic of orchestrating Terraform, and some of the challenges and areas around that. But it was still ruled by a single environment file, a state file for that environment. And these refer to the modules that we've created here. In this post, we’ll cover Terraform looping constructs. He didn't get the memo about doing a terraform plan first, he reckons all is well. And it's using Kubernetes as the mechanism for deploying the microservices. That’s not very useful. Use a proxy with Terraform. This time with two different variables and flatter data structures. So, who builds the infrastructure that builds infrastructure? So it's a little bit of a pain, but you can get around it. I can give it to one of my new team members, Frankie, and he's going to make the change for me”. A Terraform module only consists of the top-level configuration files in a directory; nested directories are treated as completely separate modules, and are not automatically included in the configuration. There should also be a .psm1 file that contains the code (unless it's a compiled module). And she discovered programmable infrastructure and Terraform, she’s excited, this is going to make a big difference to help her manage the infrastructure differently. We're going to use it to create the underlying infrastructure. I'm working on a brand-new project where I don't have to worry about any legacy Terraform config. So you might define your Terraform configuration and all the developers, all of the people who are involved in creating infrastructure, go to Jenkins and say, run the creation of whatever the particular environment is that you want. We've isolated and reduced our risk. My point is that it's not about the structure of your code, you also need to think about how you're going to evolve the processes and the orchestration system that manages this. And then you have the logical or … And now that you've got separate areas for your test and production, you can have different variables that configure things differently. They've further isolated the changes to the system, and they've reduced messing up one part of the infrastructure that's potentially unrelated to the other. So specifically with the S3 backend, you have the concept of locking, and this is only a very recent thing that was introduced from 0.9 onward, but it's handy from a team perspective when you want to try and prevent some of your teammates from potentially clobbering your stuff. Now we simply add these base modules as well. I didn't try it, but I expect another way to do this would've been to re-insert the module declaration, run terraform get to install it, and then edit the module's config in .terraform/modules to still have the provider blocks but remove all of the resources. So you may have a core team that's responsible for setting up fundamental parts of infrastructure, the VPC's, because maybe there's direct connect or something that is a little bit more complicated to set up, and then other teams which are responsible for creating other sections. So if they get to the point where this is the type of setup they have, they'll have a whole team which is dedicated to managing the infrastructure that builds the infrastructure. But this starts getting a little complicated. We did not have to set these extra attributes when we were using the configuration block syntax. It's not perfect, because stuff goes wrong, and then inevitably you have to download it onto a laptop anyway and taint and apply and fix things. You'll end up having nested modules, or modules within modules. Unfortunately, there was a little bit of a typo in the configuration, and the same variable that was being used to configure the bastion box was passed into the Kubernetes node cluster. Building a map instead of a tuple from nested for in values. If you ever happen to write some serious PowerShell scripts, you may end up confusing them and it might result in that help won't work as actually intended. For example, let’s say we first use the code above and run a terraform apply. If we go back to the multi-Terralith, which was the previous setup, we'd at least manage to evolve our environments separately, we had more intuitive configuration, and with the Terramod setup, we've taken the intuitive configuration forward. So there's not a massive change that you need to do to make this work, but the setup is that previously we still had our reference to our core module, so here we have the core Terraform module file itself, and it's still incorporated to the core module itself, but now it explicitly has to also export the output of the module to make it output for itself, so that other services that want to reuse its core input will be able to do so. 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