Over the last few years there has been a definite increase in the use of IaC (Infrastructure as Code) within cloud development and companies seem to choose a single team to create/maintain their infrastructure, or each application team to create/maintain their infrastructure, or a combination of the two.

No matter which direction is chosen there are some considerations in maintaining infrastructure as code.

• Source control the IaC
• Keep plain text secrets out of source control
• Applying least privilege to who can change the production infrastructure
• Reviewing the changes to the infrastructure
• Easy to deploy infrastructure changes
• Reliable infrastructure deployments

All of these things are easily achieved with any source control, a good review process and a well defined deployment pipeline, but this article is about “Should I co-locate my Infrastructure as Code with my application?“

I have certainly co-located IaC myself when working in an applications team deploying to Azure, keeping ARM (Azure Resource Management) templates in a folder along side my application in source control, so when the code is built the infrastructure can also be created/updated during the deployment process.

There are many benefits to this as the team can:

• Maintain a single repository to hold code and IaC
• See what infrastructure they are responsible for
• Decide/change what technology is used for their application e.g. changing the data store type or introducing a message bus, etc.
• Apply monitoring/alerting to their application easily
• Deploy to an environment knowing the required infrastructure will be created/updated

Sounds like I’ve answered the question, and that I agree that I should co-locate my IaC with my application, hmmm, well not quite, this only considers a single application and team and does not consider multiple teams or shared infrastructure.

So what if there are multiple teams, each independent and not requiring any shared infrastructure, in this scenario co-locating the IaC would give the same benefits as a single team/application.

Now what if there are multiple teams and shared infrastructure? Co-locating all the IaC in this scenario doesn’t make any sense as the shared infrastructure doesn’t belong to any application. The multiple teams could share this infrastructure and maintain it between them or another team could be responsible, depending on the team makeup.

Summary

I believe that co-locating the application specific IaC with the application code to be a good thing and gives the application team full control over their application. However any non-application specific IaC should be located away from the application, this maybe Virtual Networks, Cloudflare configuration, Application Gateways, etc.

However you maintain your infrastructure at the moment, consider this may change as applications grow or you introduce multiple applications. I suggest reviewing and revising how you manage infrastructure on a regular basis, continue to improve processes and practices and find the best way to build and maintain your cloud infrastructure.

Additional Information

If you are unfamiliar with IaC then I suggested looking at the following links:
Azure ARM templates
Azure CLI
Ansible
Terraform
Pulumi