I'm using Terraform to deploy Azure resources and now want to deploy across multiple regions.
I'm finding even with Modules I'm repeating code, once for each region.
How should I be writing code for multi region? I can't find any best practices
You could create a list variable and put your regions inside.
Then you could create a for loop and create the resource for each region. This approach works only when you really want to have each resource in each region.
It really depends on your resources. Some resources are reasonably maintained as multi-region within a single module, but this is rare. This would be a case where a module specifically addresses resources in multiple regions, with some kind of unifying logic for those resources. Since regions are typically very independent by design, this is typically an anti-pattern.
Often, it is more sane to use an infrastructure module (or root module, which means the same thing) per region. Some methodologies would have you use a different directory for each region, and again per environment. Yes, you're repeating yourself, but not that much. Your root modules should usually be pretty small and opinionated, serving as a hub for modules and top-level resources to be called.
Yes, you should keep your code DRY, but don't get carried away with it. Some duplication for the sake of organizing resources is totally acceptable.
In the cases where this is truly a problem (large root modules, and/or many regions across many environments), there are tools that can handle this effectively for you. Terragrunt is a fairly effective one, and can template your root modules (including their backend configuration) via a single code location, which is then callable via fairly small files. This can help to deduplicate a codebase like the one I just described.
You may also design your infrastructure modules to be re-usable by defining variables for regional and environmental variances between deployments. Backend configuration is also configurable during Terraform runtime via CLI or environment variable settings. Between these two, you can create infrastructure modules that are capable of being applied in arbitrary environments and regions. I like this better than Terragrunt's approach, because it's much simpler.
How you call these re-usable modules is up to your orchestration implementation, be that a CI/CD system, Kubernetes, Terraform Enterprise/Cloud, whatever.
Hopefully that helps you to make a decision.
Related
I have 3 environments to manage via Terraform: dev, staging, prod.
An example of use case is below:
create a "common" service account for each environment (sa-xxx#dev + sa-xxx#staging + sa-xxx#prod)
create a "dev-specific" role for this sa-xxx#dev SA
create a "staging-specific" role for this sa-xxx#staging SA
create a "prod-specific" role for this sa-xxx#prod SA
How can I easily manage common & specific resources for each environment?
Terraform is very simple if all environments are equals, but for specificities it looks more complicated. The goal is have a structural way to manage it, and then to avoid:
code duplication in 3 distinct folders
"count" conditions in each tf resource definition
It should be possible for Terraform to look into current root folder UNION dev/staging/prod folder (depending on the environment).
The need is very simple but implementation seems so difficult.
Thanks for help ! :)
This is a pretty broad question and so it's hard to answer specifically, but one general answer to this question is to make use of shared modules as a means for sharing code between your separate configurations.
The Module Composition guide describes some different patterns that might help you in your goal. The idea would be to make each of your configurations share modules wherever it makes sense for them to do so but to also potentially use different modules -- or the same modules but with different relationships/cardinalities -- so that your configurations can represent both what is the same and what is different between each of them.
One way would be to put shared resources in a common configuration managed in a remote state. Then in other configurations, you can refer to the shared, remote state using terraform_remote_state data source.
We are working on creating various terraform modules for Azure cloud in our organization. I have a basic doubt on using these modules.
Lets say we have a module created for creating resource groups. When we write a module for storage container, Would it be better to use the resource group module inside the storage module itself or would it be better to let the user terraform script handle it specifying multiple module resource. Eg,
module resourcegroup {
…
}
module storage {
}
Thanks,
Hound
What you're considering here is a design tradeoff rather than a question with a universal answer. With that said, the Terraform documentation section Module Composition recommends that you use only one level of module nesting where possible, and then have the root module connect the outputs from one module into the inputs of another.
One situation where you might decide to go against that advice and create multiple levels of nesting is when you want to write a module which intentionally constrains or raises the level of abstraction of another module written by someone else. Modules shared on Terraform Registry are often very general in order to serve various different use-cases, but those modules might also encapsulate some design best-practices for the system in question and so you might choose to wrap one or more of those general modules in a more specific module that more directly meets your use-case, and hopefully in turn make your "wrapper module" easier to use.
However, it's always important to keep in mind that although Terraform modules can in some sense encapsulate complexity, in the case of Terraform they can't truly hide that complexity the way we might expect for libraries in general-purpose languages, because the maintainer of the root module is ultimately responsible for understanding the full consequences of applying a plan, which involves reviewing all of the proposed changes even to resources encapsulated in nested modules.
We have just started a new project in our company which would help dev teams and operators to be able to provision cloud infrastructure as self-service. We plan to go with terraform and publishing modules based on business requirements, enterprise and security compliance (naming convention, forbidden values, etc).
Our new Cloud architect suggest we create the following structure.
Resources Modules
Wrappers around single terraform resource. 1:1 mapping
Eg: resource azurerm_vnet would have a module that wrap all the input and output variables and the resource.
Core Modules
Small modules which use resources modules.
At this level we would setup some compliance requirements, enforcing values, etc.
Eg. Module which create a storage account but some values are enforced (https only, no anonymous, etc), setup diagnostic settings with defaults, allowed locations etc
Modules
More complex infrastructure that would use core modules.
First, Core Modules and Modules for me would make sense since they contains a set of requirements/resources/business cases.
But I think having the Resources modules is a bad idea.
The architect reasons were:
Avoid duplication of terraform default resources
Since all other modules would use the resource if you need to block a property, refactor or enforce policy it would be at a single place.
This is the way he did in previous jobs
He talked with someone at Hashicorp which approved that structure.
Why I dislike the idea:
it doesn't avoid duplication of code, instead of duplicating a terraform resource you are duplicating modules and you get useless information in the state.
Hard to maintain, we are a small team, we would not be able to keep up with all the changes coming from terraform and providers.
It doesn't help for refactoring
I think policies/compliance should be enforced at another level. Core/Modules is a good start but we could leverage tools like terraform-compliance, Azure Policy, etc.
Terraform suggest otherwise
We had a debate on this and the discussion ended with me giving up because I felt I hadn't enough experience to challenge further.
What would be your take on this?
Not sure there is going to be a right or wrong answer for this one, but I am just interested how people manage Terraform in the real world? In terms of do you use modules, different environments and collaborations.
At the moment we are planning on having a production, dev and test environments. All similar.
Now at the moment I have made my terraform files in a way that define individual components of AWS, so say one for, VPC, IAM, EC2, Monitoring (CloudWatch + CloudTrail + CloudConfig) etc. And there is one variable file and .tfvars for the above, so the files are portable (all environments will be the same). So if you need to change something its all in one place. Also means if we have a specific project running I can create a tf file defining all the resource for the project and drop it in, then once its completed remove it.
Each environment has its own folder structure on our Terraform server.
Is this too simplistic? I keep looking at module.
Also does anyone have experience of collaboration with Terraform, as in different teams? I have been looking at things like Atlantis to tie into GitHub, so any changes need to be approved. But also at the sametime with the correct IAM role I can limit what Terraform can change.
Like I said may not be a wrong of right answer just interested in how people are managing terraform and their experiences.
Thanks
My answer is just an use case...
We are using terraform for an application deployed for several customers each having small specific configuration features.
We have only one CVS repository. We don't use CVS branches mechanism.
For each folder, we have remote states at least to share states between developers.
We are using one global folder having remote states also to share states between customers configurations
We are using one folder per customer and using workspaces (former environment) for each context for each customer (prod:blue/green, stage)
For common infrastructure chunks shared by all customers, we use module
We mainly use variables to reduce the number of specific files in each customer folders.
Hope this will help you...
Best practices to perform multi cloud using ansible
As a best practice, I would implement three separate playbooks and three different inventories to keep things simple. You could put together some logic to do conditionals based on the inventory and cloud provider be used, but why would you need to?
I would then create separate roles for implementing the required resources, (from an AWS perspective) create_vpc (may include dhcp options and IGW), create_routes (and route tables), create_NACLs, create_subnets, create security_groups, launch_asg(includes launch configuration), create_nat_gateway, create_nat_instance, create_elb, get_subnet_ids, get_vpc_id. The reason for creating the separate roles would to allow for flexibility in implementing resources and reuse of code.
You could easily write everything as the one playbook, and I would even recommend doing this initially to see how things work (getting familiar with ansible modules), then turn it into roles to allow for code reuse.
Include a shared variable file, (include_vars) to implement the various subnets and load balancers across the different cloud providers. This would result in three of the same environments implemented in each cloud provider.
I'm looking to implement this as a home project to learn about the differences between the different vendor offerings, based on my AWS knowledge.