2. TERRAFORM
A. Introduction:
• What is Terrafrom
• Why use Terraform
• Providers
B. Installation & Setting up Lab
• Installing Terraform – Windows users
• Installing Terraform – Linux users
• Setting up AWS Account
C. Deploying Infrastructure with Terraform
• Creating First EC2 Instance with Terraform
• Understanding Resources and Providers
• Destroying Infrastructure with Terraform
• Terraform state
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3. D. Interpolation, Attributes & Variables:
• Attributes and Output Values
• Referencing Cross-Account Resource Attributes
• Terraform Variables
E. Terraform Provisioners
• Understanding Provisioners in
Terraform
• Implementing remote-exec
provisioners
• Implementing local-exec
provisioners
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4. F. Terraform Modules & Workspaces:
• DRY Principle
• Implementing EC2 module with Terraform
• Variables and Terraform Modules
• Terraform Workspace
G. Discussions
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5. A. INTRODUCTION
What is Terraform?
• Terraform is a tool for building, changing, and versioning
infrastructure safely and efficiently. Terraform can manage existing
and popular service providers as well as custom in-house solutions.
• Configuration files describe to Terraform the components needed
to run a single application or your entire datacenter. Terraform
generates an execution plan describing what it will do to reach the
desired state, and then executes it to build the described
infrastructure. As the configuration changes, Terraform is able to
determine what changed and create incremental execution plans
which can be applied.
• The infrastructure Terraform can manage includes low-level
components such as compute instances, storage, and networking, as
well as high-level components such as DNS entries, SaaS features, etc.
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6. Key Features:
Infrastructure as Code
Infrastructure is described using a high-level configuration syntax. This allows a blueprint of your
datacenter to be versioned and treated as you would any other code. Additionally, infrastructure
can be shared and re-used.
Execution Plans
Terraform has a "planning" step where it generates an execution plan. The execution plan shows
what Terraform will do when you call apply. This lets you avoid any surprises when Terraform
manipulates infrastructure.
Change Automation
Complex changesets can be applied to your infrastructure with minimal human interaction. With
the previously mentioned execution plan and resource graph, you know exactly what Terraform
will change and in what order, avoiding many possible human errors.
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12. C. Deploying Infrastructure with Terraform
• Creating First EC2 Instance with Terraform
1. Go to AWS console and launch an ec2 instance to manage or create the
infrastructure . Install terraform on that and configure the environment path.
2. Now create a file with terraform code with .tf extension to launch an ec2-instance
.
3. It can be written in HCL (Hashicorp Configuration Language) or JSON.
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16. • Commands :
1. $ terraform init // initializing and installing the plugins
2. $ terraform validate // validating the terraform files
3. $ terraform plan //testing the configuration files before run
4. $ terraform apply //applying and running the code mentioned
inside the terraform files
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18. • Destroying Infrastructure with Terraform
terraform destroy // destroy all resources mention in the .tf file
terraform destroy -target aws_instance.myec2 // destroy the target only
=> After destroying the resources do comment out the resources inside terraform
file. Otherwise it will recreate again
Infrastructure managed by Terraform will be destroyed. This will ask for
confirmation before destroying. The terraform destroy command terminates
resources defined in your Terraform configuration. This command is the
reverse of terraform apply in that it terminates all the resources specified by
the configuration. It does not destroy resources running elsewhere that are
not described in the current configuration.
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19. • Terraform State
Terraform must store state about your managed infrastructure and configuration. This state is
used by Terraform to map real world resources to your configuration, keep track of metadata,
and to improve performance for large infrastructures. This state is stored by default in a
local file named "terraform.
Desired State:
It is the state where you have defined in your configuration, with the actual state of your
existing resources.
Current State:
Current configuration which is running in the environment and mentioned in the local file.
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21. To refresh the current state:
terraform refresh
Scenario:
If you change a parameter manually in any services inside AWS and then you want to
roll back to previous value then it is mandatory to have it inside the desired state files.
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