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Terraform remote-exec Provisioner

Step-00: Pre-requisites

  • Create a EC2 Key pain with name terraform-key and copy the terraform-key.pem file in the folder private-key in terraform-manifest folder
  • Connection Block for provisioners uses this to connect to newly created EC2 instance to copy files using file provisioner, execute scripts using remote-exec provisioner

Step-01: Introduction

  • Understand about remote-exec Provisioner
  • The remote-exec provisioner invokes a script on a remote resource after it is created.
  • This can be used to run a configuration management tool, bootstrap into a cluster, etc.

Step-02: Create / Review Provisioner configuration

  • Usecase:
  • We will copy a file named file-copy.html using File Provisioner to "/tmp" directory
  • Using remote-exec provisioner, using linux commands we will in-turn copy the file to Apache Webserver static content directory /var/www/html and access it via browser once it is provisioned
 # Copies the file-copy.html file to /tmp/file-copy.html
  provisioner "file" {
    source      = "apps/file-copy.html"
    destination = "/tmp/file-copy.html"
  }

# Copies the file to Apache Webserver /var/www/html directory
  provisioner "remote-exec" {
    inline = [
      "sleep 120",  # Will sleep for 120 seconds to ensure Apache webserver is provisioned using user_data
      "sudo cp /tmp/file-copy.html /var/www/html"
    ]
  }

Step-03: Review Terraform manifests & Execute Terraform Commands

# Terraform Initialize
terraform init

# Terraform Validate
terraform validate

# Terraform Format
terraform fmt

# Terraform Plan
terraform plan

# Terraform Apply
terraform apply -auto-approve

# Verify
1) Login to EC2 Instance
chmod 400 private-key/terraform-key.pem 
ssh -i private-key/terraform-key.pem ec2-user@IP_ADDRESSS_OF_YOUR_VM
ssh -i private-key/terraform-key.pem ec2-user@54.197.54.126

2) Verify /tmp for file named file-copy.html all files copied (ls -lrt /tmp/file-copy.html)
3) Verify /var/www/html for a file named file-copy.html (ls -lrt /var/www/html/file-copy.html)
4) Access via browser http://<Public-IP>/file-copy.html

Step-04: Clean-Up Resources & local working directory

# Terraform Destroy
terraform destroy -auto-approve

# Delete Terraform files 
rm -rf .terraform*
rm -rf terraform.tfstate*