The templates play a vital part in automation. This also applies to Terraform processes, which is a solution for automating infrastructure lifecycle management. Infrastructure as code (IaC) has enabled us to apply programming concepts to cloud infrastructure management, resulting in greater consistency, faster provisioning, decreased manual maintenance efforts, and, as a result, lower risks.
In this post, we'll go over the fundamentals of Terraform Templates and examine potential use cases and examples. In summary, if the apps hosted on your infrastructure depend on particular configuration files, which are often not part of the application repository, Terraform templates assist manage those files in dynamic ways.
What are Terraform Templates?
Terraform templates are configuration files that use Hashicorp Configuration Language (HCL), a declarative configuration language, to specify and describe the infrastructure resources necessary for a certain application or environment.
These templates have the ".tf" extension and allow users to code infrastructure, resulting in consistent and reproducible deployments.
Users may describe and configure the relationships and attributes of various resources inside a template, including virtual machines, IAM components, storage resources, and networking components. When run using the Terraform CLI, these templates are translated into a collection of operations that create the stated infrastructure on the target provider.
Spacelift is an excellent tool for managing your Terraform infrastructure, creating more complex Terraform workflows, and managing AWS credentials per run rather than using a static pair on your local machine. It includes Git workflows, policy as code, programmatic configuration, context sharing, drift detection, and many other useful features right out of the box.
An infrastructure state to be attained is defined by a set of files called a terraform template. Various configuration files, including those for resources, variables, and modules, are included.
It's usually up to you whether to store the Terraform template files individually or all under one configuration file.
Here are some essential words and ideas to become familiar with before you start creating any terraform templates:
Blocks: These are containers of sorts that always start with the name of the type of block—a resource, variable, or provider, for example. The number of labels will be specified based on the kind of block. Then, the content is defined inside the curly brackets that open and close ('\' and'}').
Comments: You can always add comments to a line of code to explain what it does, and to make the code easier to read. To define the single-line comments, use either "#" or "//". Between "/*" and "*/" are written multi-line comments.
Arguments are the name and value pairs that are associated with a specific name inside a block. The equal to (=) sign comes after the name, which is referred to as a "identifier." To the right of the "=" sign is written a specific value or expression. An identifier or name should never begin with a number and can instead contain a letter, a number, an underscore (_), or a dash (-).
Functions: Pre-defined functions are supported and can be used to manipulate values within expressions. Using function names and values to pass to the function in between the opening and closing brackets ('(' and ')', respectively) is how you use functions. You can only use the built-in functions, though, and cannot define your own. We encourage you to take some time to review the pre-built functions that Terraform has provided, even though we are unable to cover them all in this blog post.
Benefits of Terraform Templates?
A method for grouping Terraform scripts together as modules is provided by Terraform. Modules are reusable infrastructure parts that serve as the foundation for the construction of more specialized infrastructure parts.
Using input variables, modules provide a means of customizing the components that are included. A mechanism to regulate the scale, range, kind, and other elements of infrastructure provisioning is through input variables.
One excellent method to increase the flexibility offered by modules is to use Terraform Templates. The module is more adaptable and reusable thanks to templates, which also manage the settings and data files.
Similar to modules, the target resource's actual configuration or data files are shaped by the use of template files driven by input variables.
Key concepts for Terraform Templates?
Three components are combined in Terraform templates: template files themselves, string literals, and templatefile functions.
Templatefile Operation:- There are two inputs that the templatefile() method accepts:
A variable variable (*.tftpl) that may be a list or a map. The intended format data is represented by the UTF-8 encoded text found in the template file. Applications require configuration files, for instance, and these files come in several formats. Terraform's string literals, which aid substitute the real values specified in variables, are supported by these files. The Terraform Variables offer a mechanism to dynamically set values in these template files for the final configuration. Verify that the template files are on the disk before running.
The Terraform template file the template_file data source has been replaced with the templatefile function for Terraform versions 0.12 and onwards. This function may be used directly in expressions without the need to create a separate data source.