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Infrastructure as Code Terraform

Overview

Infrastructure as Code is the practice of defining and managing the logic used to provision infrastructure as versioned artifacts in the same way that code artifacts have traditionally been handled. There are a number of different tools and frameworks available that enable this type of approach. The IBM Garage for Cloud Developer Tools currently leverage Terraform as the technology used to implement the Infrastructure as Code strategy.

The IasC terraform logic is stored in two repositories:

This guide will walk through the various files that make up the Infrastructure as Code components and how to customize them. The Installation Overview walks through how to perform an install with the Iteration Zero scripts.

Iteration Zero terraform scripts

The Iteration Zero terraform scripts make use of the modules to provision and prepare an environment. The logic is provided as stages that can be removed and added as needed.

Stages

The files in the stages and stages-crc folders provide Terraform files that make use of external Terraform modules to provision resources. The different resources are logically grouped with stage numbers and names for the resource provided. All of the stages are processed by the Terraform apply at the same time and Terraform works out the sequencing of execution based on the dependencies between the modules.

The Iteration Zero application comes with a pre-defined set of software and services that will be provisioned. For more advanced situations, that set of modules can be easily customized.

  • Removing a stage

    To remove a stage, simply delete or move a file out of the stages directory

  • Adding a stage

    To add a stage, define a new stage file and reference the desired module. Any necessary variables can be referenced from the base variables or the output from the other modules.

  • Modifying a stage

    Any of the values for the variables in variables.tf or in the stage files can be updated to change the results of what is built

Environment configuration

There a number of files used to provide the overall configuration for the environment that will be provisioned.

  • credentials.template

    Template file for the credentials.properties

  • credentials.properties

    File containing the API key and Classic Infrastructure credentials needed to run the scripts

  • terraform/settings/environment.tfvars

    General configuration values for the environment, like region, resource group and cluster type

  • terraform/settings/vlan.tfvars

    Configuration values for the IBM Cloud vlan settings needed for the creation of a new cluster

  • terraform/stages/variables.tf or terraform/stages-crc/variables.tf

    Defined variables for the various stages and, in some cases, default values.

Scripts

  • launch.sh

    Launches a container image from the Docker Hub registry that contains all the tools necessary to run the terraform scripts and opens into a shell where the Terraform logic can be run

  • terraform/runTerraform.sh

    Based on the values configured in environment.tfvars, this script creates the terraform/workspace directory, copies the appropriate Terraform files into that directory, then applies the Terraform scripts

  • terraform/scripts/apply.sh

    Applies the Terraform scripts. This script is copied into the terraform/workspace directory during the runTerraform.sh logic. It is then available to rerun the Terraform logic without having to set the terraform/workspace directory up again.

  • terraform/scripts/destroy-cluster.sh

    Helper script that destroys the IBM Cloud cluster to clean up the environment

  • terraform/scripts/destroy-services.sh

    Helper script that destroys services that have been provisioned in IBM Cloud. It works against the resource group that has been configured in the environment.tfvars file. Any values passed in as arguments will be used to do a regular expression match to exclude services from the list of those that will be destroyed.

Garage Terraform Modules

The terraform modules project contains the building block components that can be used to create a provisioned environment. The modules are organized into one of three major categories:

  • cloud-managed

    Modules that provision infrastructure (cluster and/or services) into a managed cloud environment

  • self-managed

    Modules that provision infrastructure into a self-managed environment (e.g. software deployed into a cluster)

  • generic

    Modules that can be applied independent of the environment (e.g. software that is installed into a running kubernetes environment)

A listing of the modules is shown below:

modules